[Tactical Open Wire Pole Line Construction]
[From the U.S. Government Publishing Office, www.gpo.gov]
TACTICAL
OPEN WIRE
POLE LINE
CONSTRUCTION
WAR DEPARTMENT
5 MAY 1944
W 1,35; II-36S
DEPARTMENT TECHNICAL MANUAL
NON-CIRCULATING
LIBRARY
OF
NORTH TEXAS
STATE TEACHERS COLLEGE DENTON, TEXAS
Call Number
Author____2____.1 -.I ___________________.......
Z $ Title. _____________________________________________________
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N. T. S. T. C. Library MY c mc
(Form 8 rev.) -> **3
U• S• War department•
... Tactical open wire pole line construction. ^Washington4 War department, 1944.
(Its manual, TM 11-368)
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WAR DEPARTMENT TECHNICAL MANUAL
TM 11-368
TACTICAL
OPEN WIRE
POLE LINE
CONSTRUCTION
WAR DEPARTMENT
5 MAY 1944
WAR DEPARTMENT, Washington 25, D. C., 5 May 1944.
TM 11-368, War Department Technical Manual, Tactical Open Wire Pole Line Construction, is published for the information and guidance of all concerned.
[A.G. 300.7 (23 Nov 42).]
By order of the Secretary of War:
G.G MARSHALL,
Chief of Staff.
Official:
J. A. ULIO, Major General, The Adjutant General.
Distribution:
IBn 11 (5); IC 11 (30).
(For explanation of symbols see FM 21-6.)
ii
127970
TABLE OF CONTENTS
CHAPTER. 1. General. Paragraphs Page
SECTION I. Introductory information................. 1-8 1
II. General transmission considerations
affecting construction........... 9-18 7
III. Transposition arrangements.......... 19-28 15
CHAPTER 2. Planning tactical open wire pole lines.
SECTION I. Advance planning of construction
and routing.......................... 29-36 23
II. Route survey and completion of planning ...................................... 37-46 26
III. Detailed marking and layout of the
line route .......................... 47-62 31
IV. Symbols and abbreviations........... 63-70 40
CHAPTER 3. Engineering requirements .................... 71-87 45
CHAPTER 4. Constructing tactical open wire pole lines.
SECTION I. Organizing the line construction project ................................,.......... 88-92 69
II. Signals for use by line construction personnel .............................. 93-95 71
III. Method of framing, erecting, and guying open wire pole line supports ....................................... 96-122 76
IV. Stringing wire ........................ 123-132 116
V. Tensioning, tying, and transposing wires...................................... 134-144 122
VI. Splicing wire ......................... 145-151 135
VII. Insulated wire in open wire lines... 152-162 142
CHAPTER 5. Maintenance and removal of open wire lines.
SECTION I. Inspections and repairs................ 163-176 153
II. Location of faults on open wire lines 177-181 156
III. Line removal........................... 182-187 159
iii
TABLE OF CONTENTS
CHAPTER 6. Supplementary data. Paragraphs Page
SECTION I. Safety practices.................... 188-196 163
II. Care of tools...................... 197-199 166
III. Storage of crossarms and poles.... 200-203 168
IV. Supplementary transmission and considerations ............................ 204-210 170
V. Transmission design ................ 211-226 172
VI. Material requirements for tactical open wire pole lines..................... 227-235 191
INDEX ...............................
LIST OF ILLUSTRATIONS
Fig. No. Title ' Page
1. Storm loading areas in the United States......................... 4
2. Pole line structures for use under various storm loading conditions............................................................ 6
3. Data on open wire lines......................................... 10
4. Maximum pair-per-pair lengths of nonloaded cable or insulated wire for entrance or intermediate use on open wire lines........................................................... 12
5. Schematic circuit arrangement for loaded spiral-four inserts in open wire lines................................................. 13
6. Approximate attenuations of ground-return circuits............ 14
7. Numbering of pin positions.................................... _ 16
8. Transpositions for first 4-pair crossarm......................... 17
9. Transpositions for second 4-pair crossarm_______s.... ........... 18
10. Transpositions at S-poles of a 2-crossarm line.........-........ 19
11. Sighting stake at line comer................................. 34
12, Typical pole location stake markings.......................... 36
13. Form of notes to be kept by the pilot........................... 37
14. Span length, sag, and clearance illustrated..................... 46
15. Vertical clearances............................................. 47
16. Table of bare wire sags and tensions, 150-foot nominal spans.. 48
17. Table of bare wire sags and tensions, 200-foot nominal spans.. 49
18. Table of sags and tensions for insulated wire and cable...... 50
iv
LIST OF ILLUSTRATIONS
Fig. No. 19.
20.
21. 22.
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1 31.
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53.
Title
Oscillation table for use in measuring wire sags.......
Method of applying measured tension to line wires......
Sag gauge....................................■.........
Sighting method of measuring sag with sag gauges.......
Lead and height........................................
Methods of measuring pull of corners in the line.......
Method of using Pull Finder LC-45......................
Side and head guys.....................................
Two-and four-way storm guys ...........................
Push-brace for use with 4x4 pole.......................
Push-brace for use with round pole.....................
Schematic diagram, guying at corners where pull is less
than 50 feet ........................................
Schematic diagram, guying at two-pole corners where pull
is more than 50 feet.................................
Flat and round grade...................................
Measuring change in grade at up-pull in line...........
Measuring change in grade at down-pull in line.........
Method of measuring change in grade with four ranging poles "Go ahead” ............................................
"Go ahead slowly”......................................
"Back up” .............................................
"Back up slowly”.......................................
"Stop”................. ...............................
"Up” ..................................................
"Down” ................................................
"Hold” ................................................
"Release” or "cut off’..............;..................
"All O.K.”.............................................
''Return” or "go back”.................................
Method of framing 4x4 pole.............................
Method of making 4x4 pole from two 2x4’s...............
Framing details for round poles........................
X-frame assembly ......................................
H-fixture made with 4x4 poles..........................
Crossarm PF-92-A ......................................
4x4 pole equipped with side guy and crossarm stay......
51
52
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54
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59
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83
LIST OF ILLUSTRATIONS
Fig. No. Title Page
54. Insulator IN-15 (left) and Insulator IN-128 (right) ........... 84
55. Pin PF-59 (insulator pin) ..................................... 85
56. Depth of setting for poles..................................... 87
57. Location of Insulator IN-128 on Crossarm PF-92-A............... 88
58. Double-arming at corner transposition poles.................... 90
59- Reinforced X-frame for use at dead-ends and heavy corners 91
60. Side extension arm..............*.............................. 92
61. Pole top extension fixture, 4x4 and round poles................ 93
62. Wrap method of attaching guys.................................. 94
63. Through bolt method of attaching guys.......................... 95
64. Pike-pole method of raising poles............................. 96
65. H-fixture made with round poles................................ 98
66. Method of judging crossarm setting at corner poles.......... 99
67. Single H-fixture set to bisect corner angle.................... 99
68. Rake at comer poles .......................................... 100
69. Forms of anchors suitable for use with 4x4 poles.............. 101
70. Log (or pole section) anchor, set transversely................ 102
71. Log (or pole section) anchor, set longitudinally.............. 102
72. Method of obtaining added bearing area, transverse log anchor 103
73. Method of obtaining added bearing area, longitudinal log anchor............................................................... 103
74. Plank anchor used with Anchor Rod AH-4........................ 104
75. Tree guy for light corners, 4x4 poles......................... 105
76. Tree guy for round poles and for heavy comers, 4x4 poles.... 106
77. Method of pulling up earth anchor guys........................ 107
78. Method of pulling up guys at poles, stubs, or trees........... 108
79. Serving method of terminating strand.......................... 109
80. Swamp footing for 4x4 or round poles........................ 110
81. Swamp footing for X-frame.......«............................. Ill
82. Improvised rock anchor........................................ 112
83. Guying system for highway crossings........................... 113
84. dealing ladder made from 2x4 lumber......................... 114
85. Wire data..................................................... 116
86. Payout reels mounted on a trailer............................. 117
87. Use of wire raising Hook LC-65.............................. 118
88. Pulling wires out from payout reels set up on the ground.... 119
89- Position of wires on insulators at comers................... 121
vi
LIST OF ILLUSTRATIONS
Fig. No. Title Page
90. Position of wires on insulators in straight sections of line. 121
91. Rope support for pulling wires over crossings.................. 122
92. Snubbing wires with wire-pulling blocks........................ 123
93. Crossarm guy used in wire tensioning........................... 124
94. Method of holding wires down at up-pull........................ 124
95. Method of making wire dead-end at insulator.................... 125
96. Wire dead-end made with twisted sleeve......................... 126
97. Double dead-end with bridging connector joint.................. 126
98. Tie wire data.................................................. 127
99. Standard insulator tie....................................... 128
100. Modified horseshoe tie......................................... 129
101. Perspective view of transposition.............................. 130
102. Schematic diagram, visual method of checking transposition 130
103. Method of bringing in side leads to join the main lead in one direction...................................................... 132
104 Method of bringing in side leads to join the main lead in both directions...................................................... 132
105. Method of bringing in side leads with X-frame construction 133
106. Vibration damper for open wire................................. 134
107. Wire splicing data—rolled or pressed sleeves................... 136
108. Sleeve-Rolling Tool TL-143 .................................... 137
109. Sleeve Compressing Tool TL-217................................. 138
110. Indenting sleeve to hold wire before rolling................... 139
111. Wire splicing data—twisted sleeves............................. 140
112. Making a twisted sleeve splice................................ 141
113. Western Union joint.......................................... 142
114. Method of installing No. 3 A bridging connector................ 143
115. Alternative method of installing No. 3A bridging connector 144
116. Method of installing No. 6A bridging connector................. 144
117. Method of connecting drop wires to open wire pairs........... 145
118. Clearance required for insulated wire or cable runs on open wire line supports ................................................. 146
119. Supporting drop wire at heavy corners.......................... 147
120. Supporting drop wire in runs along the lead.................... 147
121. Intermediate support for spiral-four cable, using hanger..... 148
122. Connecting insulated wires to bare wires on a pair-per-wire basis........................................................... 149
vii
LIST OF ILLUSTRATIONS
Fig. No. Title Page
123. Construction at H-fixture adjoining an underpass.............. 150
124. Lifting poles out of ground with pole derrick................. 160
125. Pulling poles over with a winch rope.......................... 162
126. Data on insulated pairs and cables............................ 173
127. Approximate bridging losses at 1,000 cycles................... 175
128. Maximum allowable voice-frequency repeater gains, Telephone Repeater TP-14 2-wire circuits................................ 177
129. Repeater section lengths for Converter CF-4-(&) (carrier) and Repeater CF-5-(&) (carrier) equipment in 4-pair or 8-pair open wire lines........................................... 178
130. Estimated maximum repeater section lengths using Telephone Terminal CF-l-(&) (carrier) and Repeater CF-3 (carrier) and the 2-wire Carrier Hybrid CF-7-(&) on a 4-pair or 8-pair open wire line................................ 180
131. Estimated maximum repeater section lengths using Telephone Terminal CF-l-(&) (carrier) and Repeater CF-3 (carrier) and the 2-wire Carrier Hybrid CF-7-(&) on rubber-covered pairs or cable.................................... 181
132. Guide for determining operating ranges—368 operations per minute ......................................................... 183
133. Information on repeater section lengths for Telephone Terminal CF-l-(&) (carrier) and Repeater CF-3-(&) (carrier) on 4-pair or 8-pair open wire lines....................... 184
134. Use of Converter CF-4-(&) (carrier, 2-wire—4-wire) and
Repeater CF-5-(&) (carrier, 2-wire) on nonloaded cable. .. 187
135. Crosstalk suppression devices for installation at repeaters. 190
viii
DESTRUCTION NOTICE
WHY —To prevent the enemy from using or salvaging this equipment for his benefit.
WHEN—When ordered by your commander.
HOW — 1. Smash—Use sledges, axes, handaxes, pickaxes, hammers, crowbars, heavy tools, etc.
2. Cut—Use axes, handaxes, machetes, etc.
3. Burn—Use gasoline, kerosene, oil, flame throwers, incendiary grenades, etc.
4. Explosives—Use firearms, grenades, TNT, etc.
5. Disposal—Bury in slit trenches, fox holes, other holes. Throw in streams. Scatter.
USE ANYTHING IMMEDIATELY AVAILABLE FOR DESTRUCTION OF THIS EQUIPMENT.
WHAT—1. Smash—Insulators and tools.
2. Cut—Poles, wire strand, cable, body belts, etc.
3. Bend and/or break—Poles, crossarms, and wire by:
(1) Looping rope or winch line over all wires in a span and pulling at right angles,
(2) Securing a rope or winch line around top of pole and pulling along the lead until all wires are broken, or
(3) Securing a rope or winch line around the end of a crossarm and pull as in (2).
4. Burn—Stored poles, pole lumber, crossarms, and pins.
5. Bury or scatter—Any or all of the above pieces which might be salvageable, after breaking.
DESTROY EVERYTHING
ix
CHAPTER 1 GENERAL
SECTION 1
Introductory Information
1. PURPOSE. The purpose of this manual is to describe the methods of constructing and maintaining tactical open wire pole lines.
2. SCOPE.
a. The procedures recommended herein for tactical open wire pole line construction are based upon practices and principles which have been evolved in American commercial telephone practice with such modifications as are necessary to fit them to military requirements. The basic type of pole line construction described has four pairs of wires laid out in a standard single-cro3s.irm transposition pattern and supported upon various types of structures. Contraction of 2-pair open wire lines and 2-crossstrm lines with a omimum capacity of eight pairs is also described.
b. The subject matter includes line planning, surveying and layout, construction, maintenance, and recovery. Whenever possible die practices and methods are outlined broadly to allow for the exercise of judgment ia solving individual problems. If is not ratessded to bind construction p&rsotsnel wish fixed rales which may prove impracticable under field ccnditis&s. li it important that systematic procedures be observed. Personnel required fa phtm or supervise construction should pay particular attention to she sections coucam-ing general transmission considerations affecting construction, line planning and layout, and transposition arrangement. Efficient constmxion of lines which will function properly when completed is dependent upon strict attention these preconstruction pliases of the work.
c. Construction methods and transmission factors recommended herein are suitable for training purposes and also for reference purposes for use by experienced line construction personnel.
d. The chapter on supplementary data includes detailed transmission information, outlines safety practices, describes the use and care of tools, suggests methods of storing poles and crossarms, and provides lists showing the quantities and types of materials required for constructing the lines described herein.
1
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 3-4
3. REFERENCES.
a. Other texts closely related to this manual are: TM 11-363, Pole Line Construction; TM 11-369, Spiral-Four Cable; TM 11-462, Reference Data; FM 24-5, Signal Communication; and FM 5-35, Reference Data (Rope Splicing and Dynamiting). These manuals should be thoroughly studied by all personnel engaged in the construction and maintenance of tactical open wire lines. Bell System Practices, Series G, Outside Plant Construction and Maintenance, will also be of value.
b. The principal communication equipment used with these lines is de-, scribed in:
TM 11-341,
TM 11-342,
TM 11-355, TM 11-355B, TM 11-2003, TM 11-2004, TM 11-2005, TM 11-2008,
TM 11-2014,
Telephone Terminal CF-l-A (Carrier) and
Repeater CF-3-A (Carrier);
Ringing Equipments EE-100-T1, EE-100-A (Voice Frequency), and EE-101-A (Voice Frequency);
Telegraph Terminal CF-2-A (Carrier);
Telegraph Terminal CF-2-B (Carrier);
Carrier Hybrid CF-7; .
Repeater Set TC-18 (Terminal);
Repeater Set TC-19 (Intermediate);
Converter Set TC-33 (Carrier, 2-Wire— 4-Wire) and
Repeater Set TC-37 (Carrier, 2-Wire);
Telephone Unit EE-105.
4. REQUIREMENTS FOR WHICH THE TYPE OF LINE IS DESIGNED. * The type of open wire pole line described in this manual has been designed to meet a number of general requirements of army tactical use. These requirements are as follows:
a. Electrical Performance. Military telephone and telegraph systems must provide good transmission over reasonable distances.
b. General Features of Construction. The line must support the wire properly with the required clearances above the ground. The supports should be chosen to fit ground conditions and military requirements in the area in which the line is constructed.
c. Simplicity. (1) The construction must in all cases be as simple as possible, consistent with electrical and physical requirements and economy of labor and time.
(2) The variety of component parts must be kept at a practicable minimum.
d. Economy of Material and Space. (1) The lines must employ the lightest weights and the smallest sizes of component materials consistent with proper electrical performance and physical strength requirements.
2
TM 11-368
Pars. 4-6
General
(2) Materials must be suited to compact and efficient stowage for transportation.
e. Adaptability. The line must permit construction under all reasonable conditions.
f. Reliability^ The lines must be electrically reliable and structurally sound so that dependable service and minimum maintenance will result.
♦
5. DESCRIPTION OF TACTICAL OPEN WIRE POLE LINE. The tactical open wire pole line described in this manual provides from one to four pairs of wires on a single crossarm to meet essential military requirements. A distinguishing feature of this type of line is the use of lightweight poles or other supports which can be easily handled and quickly set. However, where more than four pairs of wires are required, the basic open wire system described can be used in constructing a 2-crossarm line only if poles of sufficient length to give the prescribed vertical clearances are available. When more than four pairs of wires are required, tactical considerations will make it preferable in most instances to construct a second single-crossarm line over an alternate route.
a. One type of support used in this construction is framed from a 20-foot length of 4x4 sawed lumber, or in some cases is made from two 2x4’s. Alternative forms of support for a single-arm line are 20-foot Class 9 round timber poles, or X-frames made from 2x4’s. Poles are set in holes dug by hand or mechanically.
b. Crossarms are 334 by 434 by 88 inches and have a capacity of four, pairs of wires. The spacing between wires of a pair is 8 inches and the separation between pairs is 16 inches. Crossarms are bored for insulator pins,‘through bolts, and crossarm brace bolts so that the arms when cut in half will provide two 4-pin crossarms. Standard 8-inch wooden pins and glass insulators are used.
c. The usual conductor material is Wire W-153, 0.080 inch diameter, 40-percent conductivity, copper-steel wire (080 C-S). This wire combines high tensile strength with small size and adequate conductivity. Provision is made for the use of alternative conductor materials.
d. This line is designed for reasonable stability and freedom from swingingwire contacts under standard American storm-loading conditions (par. 6).
e. The wire transposition system is simple and easily memorized, since a pair in a given position in the line is always transposed in the same manner. Thus the original transposition pattern of a given pair remains unchanged whether other pairs are added to or removed from the line, and is independent of the type of pole structure used. A transposition pattern is given for a single-crossarm as well as for a 2-crossarm line.
6. STORM LOADING. Storm loading is defined as die eSea on an open wire pole line of the combined stresses imposed by a simultaneous occurrence
3
TM 11-368 Tactical Open Wire
Par. 6 Pole Line Construction
___________ * J / /______!----------•’
K » I M.OA*. \ TWIT ^*-0 ~
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TL-50510 XZ^X <( X
Figure 1. Storm loatiing areas in the United States.
4
TM 11468
Pars. 6-7
General
of low temperature, a coating of ice on individual wires, and a cross wind Mowing against the wires.
4. Light loading is that set of conditions in which, at a minimum temperature of 30° F, the wind exerts a maximum pressure of 12 pounds per square foot (velocity about 70 mph) against wires not covered with ice.
, b. Medium loading conditions exist when, at a minimum temperature of 15° F, wind pressure of 8 pounds per square foot is exerted against wires having an ice coating 34 inch in radial thickness. A wind velocity of about 60 mph exerts this pressure.
r. Heavy loading conditions axe based upon a minimum temperature of 0° F and a wind pressure of 8 pounds per square foot against wires covered with 3k inch radial ice coating.
d. Extra-heavy loading conditions are based upon greater ice and wind loads than those indicated for heavy loading.
e. The types of pole structures used under different storm loading conditions are given in the table in figure 2.
7. FIELD OF USE FOR OPEN WIRE POLE LINES.
4. When long circuits with high quality transmission are required, open wire lines will ordinarily be the preferred type of construction. In general, open wire lines are the primary means of communication in wire nets of higher headquarters and related establishments. Laterals from a main axis of communication will frequently be open wire lines, particularly if more or longer circuits are needed than can be provided conveniently by alternative facilities.
b. If the foregoing general principles are applied literally, a natural question arises concerning the relative fields of use of open wire lines and other conductor systems suited to trunk line use (spiral-four cable, or long range field wire). Where either open wire or insulated conductors of one form or another are satisfactory electrically, the choice of facilities depends entirely upon practical factors. These factors are: available materials, required speed of construction, probable future use and growth of the line, number of circuits required, and terrain to be covered. (See TM 11-369, Spiral-Four Cable, and paragraph 31 of this manual.)
c. Open wire lines have natural advantages, among x^hich are the following: attenuation is lower than that of other facilities (allowing wide spacing of repeaters); trouble clearing is simplified as the lines are easily accessible and trouble causes are usually evident to die eye; open wire lines are usually routed with more care than insulated conductor lines, and are therefore less subject to damage.
5
TM IE-368 Tactical Open Wire
Par. 7 Pole Line Construction
Pole line structures for use under various storm-loading conditions TYPE OF CONSTRUCTION FOR ONE CROSSARM St ‘ b _______________Comer____________ Dead-end: H-fixture
of Span section— Type __________Guy______ Type ___________^2------
storm length type of Pull of No. and of No. and
loading (ft) support (ft) support Lead/height size support Lead/ height size
0-10 4" x 4" 0.75 and above 1—109GS 0.75
Light 150 4"x4" 11-20 4"x4" 0.75 and above 1—2.2M 4"x4* and 2—2.2M
21-50* 4" x 4", H-fixture 0.75 and above 1—2.2M above
0-10 Round 0.75 and above 1—2.2M 0.75
Light* 200 Round 11-20 Round 0.75 and above 1—2.2M Round and 2—2.2M
21-50* Round, H-fixture 0.75 and above 1—2.2M above
0-10 Rpund 0.75 and above 1—2.2M 0.75 4—2.2M
Medium 200 Round 11—20 Round 0.75 and above 2—2.2M Round and or
21-50* Round, H-fixture 0.75 and above 2—2.2M above 2— 6M
0-10 Round 0.75 and above 1—2.2M 0.75
Heavy 200 Round 11—20 Round 0.75 and above 2—?2.2M Round and 2— 6M
21—50* Round, H-fixture 0.75 and above 2—2.2M above
0-10 Round 0.75 and above 1—2.2M 0.75
Extra 150 Round 11-20 Round 0.75 and above 2—2.2M Round and 2— 6M
heavy 21-50* Round, H-fixture 0.75 and above 2—2.2M above
*For comers having a pull greater than 50', divide the comer equally between 2 H-fixtures. *An alternative form of construction in light loading areas consists of 200-foot spans with round poles at comers and dead ends and 4x4 poles in straight sections of the line. This type of construction may be used when stocks of poles are otherwise inadequate, but is not preferred for general use. NOTE: Information on guying 2-crossarm lines is contained in paragraph 82. Storm guying information is contained in paragraph 83.
Figure 2. TL50511
6
TM 11-368
General Pars. 3-1®
8. LINE TREND.
a. Definition. Line trend (direction) is the direction in which the wire line is assumed to have been established. It runs from higher headquarters to lower headquarters or from rear to forward echelon. For lateral lines between posts of equal authority, the line trend is from left to right, as viewed from the common higher headquarters.
b. Significance. With open wire lines it is essential that each line be assumed to have a specific trend, since the numbering of pin positions (and thus of pairs) and the pattern of the transposition system are dependent upon the line direction. In commercial telephone usage, the line is assumed to proceed from the observer when he is facing in the direction of increasing pole numbers. The poles of open wire lines in military operations areas may not always be numbered, and reference to line direction are subject to confusion with compass direction. The term line trend (or trend of the line) is therefore used as an orienting term.
c. Applications. A trunk line from army headquarters to a corps headquarters is taken to originate at the higher headquarters (army) and the line trend is toward the lower headquarters (corps). References to the left- or right-hand side of the line assume the observer to be facing toward the lower headquarters, and thus in the direction of line trend. Pin positions, and therefore wire numbers, increase from left to right with the observer facing in the direction of line trend.
SECTION 11
General Transmission Considerations Affecting Construction
9. PURPOSE AND SCOPE. This section covers transmission considerations of specific interest to the construction personnel in constructing tactical open wire pole lines. Certain rules as to pole spacing, wire sag, etc., based on the minimum requirements for obtaining satisfactory transmission results, are given in the details of specific construction elsewhere in this manual.
10. TELEPHONE CIRCUITS AVAILABLE.
a. On a 4-pair open wire line, one voice-frequency circuit may be obtained from each pair and voice-frequency repeaters may be used as desired. A phantom circuit may be used for short distances but such a circuit will generally be poor from the standpoints of noise, and of crosstalk to and from its own side circuits or from another phantom. Instead of the voice-frequency circuit, four
608W8«O—44---2
7
TM 11-3GB Tactteal Open Wire
Pars. 16-12 Pole lAne Construction
carrier telephone channels may be obtained on one pair as described in subparagraphs b and c below.
b. When the open wire carrier applique system [Converter CF-4-(&) (Carrier) and Repeater CF-5-(&) (Carrier)] is used, all pairs on a 1- or 2-crossarm line may be equipped. The symbol (&) indicates all models and procurements of an item of equipment. This will give high-grade performance for 16 or 32 telephone circuits up to about 400 miles with a net loss of 6 db and up to 800 miles with a net loss of 9 db. Somewhat greater lengths than these may be used without much crosstalk degradation. If some of the systems on the line are shorter than these lengths, they should preferably be assigned to pairs 1-2 or 3-4.
c. When the 2-wire carrier hybrid system [Carrier Hybrid CF-7-(&) plus Terminal CF-l-(&) and Repeater CF-3-(&)] is used, the two outside pairs of the 4-pair line may be equipped, giving 8 carrier telephone circuits (plus 2 voice-frequency circuits on the other pairs) up to about 100-200 miles with a net loss of 6 db, depending on the return loss conditions. Only slightly greater lengths can be used with net loss of 9 db.
d. Approximate maximum circuit lengths of various long wire line facilities
are given below:
(1) Carrier on spiral-four cable or long range field wire on the ground ............................................................... 150 miles
(2) Carrier on spiral-four cable or long range field wire plowed
in ................................................................... 400 miles
( 3) Carrier on spiral-four cable or long range field wire, aerial.. 150 miles
(4) Open wire carrier applique on 080 copper-steel open wire 400-800miles (5) Two-wire carrier hybrid system on 080 copper-steel open
wire ........................................................... 100-200 miles
11. TELEGRAPH CIRCUITS AVAILABLE. In general, d-c telegraph circuits may be obtained on each wire by compositing; that is, 8 telegraph circuits may be obtained from a 4-pair line or 16 from an 8-pair line. When carrier facilities are superposed, one or more of the telegraph circuits probably will be needed for a signaling circuit in connection with the maintenance of the carrier systems. When the maximum number of d-c telegraph circuits are not needed or when compositing equipment is not available, one d-c telegraph circuit may be obtained from each pair by simplexing (par. 221). In addition, voice-frequency telegraph circuits may be superposed on a telephone circuit to obtain two or four voice-frequency telegraph circuits from each telephone circuit used for this purpose.
12. GENERAL TRANSMISSION LIMITATIONS. The primary object of wire lines is to transmit telephone or telegraph messages so that they may be
8
TM 11-368
General Pars. 12-15
readily understood. If there is too much noise or crosstalk, or if the circuit overloads or sings or otherwise distorts the telephone or telegraph message excessively, satisfactory service will not result. The limits given in this section and other seaions of this manual are designed to result in satisfaaory transmission.
13. ATTENUATIONS. Figure 3 gives the attenuations of open wire circuits of various gauges and materials under both wet and dry conditions. Under conditions of extreme sleet (glaze) or hoar frost, much higher attenuations will result. The use of spiral-four cable or other insulated conduaor wire which can be installed underground or on the surface may be preferred if severe ice conditions are expeaed.
14. ENTRANCE AND INTERMEDIATE INSULATED WIRE AND CABLE ON OPEN WIRE LINES. At terminals and intermediate repeater points, whenever praaicable, the open wire should be brought direaly up to the wall of the shelter and then extended as directly as possible to the repeaters or other inside apparatus on insulated wires. Certain points on open wire lines will require special arrangements. These include terminals where it is desired to conceal the location of the switchboard, intermediate repeater points, swamp crossings, passages through forested areas, etc. These arrangements may .include the use of insulated wire twin pairs (the two wires of a pair in parallel serving as one conduaor and the two wires of another pair as the other), nonloaded insulated pairs (one insulated pair per open wire pair), and loaded insulated pairs.
15. INSULATED OPEN WIRE TWIN PAIRS.
a. In general, it is desirable either to avoid or to trim off tree limbs, etc., which may touch the open wires. Where this is not practicable, insulated field wire or cable may be used instead of open wire. Locations where regular open wire is not practicable generally will be crossed with Wire W-110-B, W-143, or W-50 twin pairs, or with other insulated twin pairs, suspended above ground, with the two pairs kept well separated. To avoid excessive crosstalk, the con-struaion should be as regular as practicable; the tip and ring sides of the circuit should be kept about 8 inches apart and the separation between circuits should be made materially greater than 16 inches, if feasible. The transposition pattern of the open wire should be continued without interruption through the stretch employing spaced insulated wires. The distances between successive transposition points and the sags in the wires of a given span should be kept as uniform as praaicable.
b. The losses given in figure 3 are for perfectly spaced wires having no con-taa with tree limbs or leaves. When the spacing is poor, or when the wire
9
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 15
Data on open
Wire
weight D-c Nominal V-f talking
Breaking per loop resistance wire range without
strength mile— ohms per spacing— amplification—
Description pounds pounds loop mile inches miles for 30 db
080 H.D. copper 330 204 17.5 8 235
W-74, 104 H.D. copper 550 346 10.3 -8 370
128 H.D. copper 819 524 6.8 8 510
165 H.D. copper 1,325 870 4.1 8 750
W-153, 080 4095 copper-steel1 770 187 42.8 8 120
104 4096 copper-steel1 1,172 317 25.3 8 175
128 4096 copper-steel1 1,647 480 16.7 8 233
104 3096 copper-steel1 1,270 317 33.8 8 140
128 3096 copper-steel1 1,800 480 22.3 8 183
083 Galv steel* 703 198 130 8 80
W-145, 109 Galv steel* 1,213 340 75 8 100
W-110-B Buried twin-pair* 300 240 93 12 8
W-110-B Gnd twin-pair’ 300 240 93 12 11
W-110-B O.W. twin-pair’ 300 240 93 12 67
W-110-B O.W. twin-pair’ 300 240 93 8 65
W-110-B Tree twin-pair’ 300 240 93 — 27
W-143 O.W. twin-pair’ 340 600 17.5 8 214
W-50 O.W. twin-pair’ 400 640 13 8 250
NOTES: ’The % figure gives the conductivity of copper-steel wire as compared with a standard annealed copper wire of the same size.
*This wire is assumed to have an .8-oz. zinc coating in good condition. Much lower tensile strength and higher attenuation may be found with badly corroded wire.
*Two wires of one pair used in parallel form one side of this circuit and the two wires of another pair form the other side. The O.W. twin-pair is assumed to be strung like open wire on insulators on poles, with the two pairs separated as indicated. The ground (gnd) twin-pair is assumed to be laid on the ground with the pairs spaced approximately as indicated, but without other wires in the immediate vicinity. The buried twin-pair is assumed to be buried 8 to 12 inches deep in ordinary dry soil. The tree twin-pair is made of two W-110-B pairs tied to trees and spaced 8 to 24 inches apart. Considerable variation
Figure 3-
10
TM 11-368
Par. 15
General
wire lines
Approximate attenuation—db per mile*
Dry Wet
1 kc 8 kc 11 kc 20 kc 30 kc 1 kc 8 kc 11 kc 20 kc 30 kc
.11 .13 .14 .16 .19 .13 .15 .17 .20 .24
.074 .089 .099 .13 .15 .083 .11 .12 .16 .19
.052 .071 .080 .11 .13 .061 .088 .10 .14 .16
.034 .056 .064 .084 .10 .042 .072 .083 .11 .13
.23 .31 .32 .33 .33 .25 .34 .35 .36 .37
.16 .20 .20 .21 .21 .18 .22 .23 .24 .24
.12 .14 .14 .14 .15 .13 .16 .16 .17 .18
.21 .28 .28 .29 .29 .22 .30 .31 .32 .33
.15 .19 .20 .20 .20 .17 .22 .22 .23 .24
.36 1.2 1.4 2.1 2.5 .37 1.2 1.4 2.1 2.5
.30 1.1 1.3 1.7 2.0 .31 1.1 1.3 1.7 2.0
2.0 3.0 3.0 3.5 4.0 3.8 6.0 6.4 7.2 8.3
.85 1.4 1.5 1.8 2.1 2.7 5.5 6.2 8.1 10.2
.40 .61 63 .65 .68 .45 .63 .66 .70 .74
.43 .66 .68, .70 .73 .46 .68 .71 .75 .79
.44 .68 .70 .75 .80 1.1 1.6 1.7 2.1 2.6
.13 .14 .14 .16 .17 .14 .16 .17 .20 .23
.10 .11 .12 .14 .15 .12 .13 .14 .17 .20
in the attenuation figures for twin-pair may be expected under particular conditions and especially at the higher frequencies.
’These attenuation figures are for side circuits at 70°F and assume: the use of Insulators IN-15 and IN-128 in good condition; that trees, bushes, etc., do not touch the wires; and chat recommended construction practices are followed. Pole spacing is assumed to be 200 feet except for 080 H.D. copper and W-110-B, W-143, and W-50 O.W. twin-pair which are 150 feet. With 150-foot pole spacing on facilities, the resulting change in attenuation will be small. If ice or hoar frost forms on the wires, considerably higher attenuations may result, particularly at the higher frequencies. Phantom circuits made up from two side circuits spaced 16 inches apart will have about .8 as much attenuation at 1,000 cycles as the corresponding side circuits.
TL50512
11
Figure 3 (Continued)
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 15-16
touches a number of other objects along its course, considerably greater losses may result, and the crosstalk and noise may be greatly increased. One tree contact per 200 feet is estimated to increase the attenuation at 30 kc about 0.2 db per mile in wet weather. Twin pairs of insulated wires tied together around trees, or with both pairs fastened to the same insulator, will generally tend to have high losses, particularly in wet weather. Twin pairs of Wire W-110-B, even on insulators, will generally have higher maximum losses at 30 kc than bare 080 copper-steel pairs strung through trees. However, Wire W-110-B twin pairs on insulators are usually preferable to bare open wires when there are many tree contacts. The reasons are that the variation in loss from dry to wet weather is less; the leakage to ground, which affects d-c telegraph circuits, is less; and the crosstalk and noise caused by such contacts are less.
16. NONLOADED INSULATED WIRES OR CABLE PAIRS.
a. Where spaced twin pairs cannot be used, short seaions of nonloaded insu lated wires or cable pairs may be used. Figure 4 shows the maximum lengths of such pairs which may reasonably be used in an open wire repeater seaion without trouble from crosstalk or repeater singing. The loss of such sections at 30 kc will be about 0.1 db per repeater section. Next to a terminal or repeater, somewhat greater lengths are permissible.
Maximum pair-per-pair lengths of nonloaded cable or insulated wire for entrance or intermediate use on open wire lines
Maximum of each length (jt).
Conductors No. of lengths per repeater section.... .... 1 2 3
WC-548 or CC-368 125 $0 70
W-1431 80 55 45
W-50* 65 45 40
WC-548, CC-358, or CC-368 (twin-pair) 45 35 25
CC-345 orCC-355A! 105 75 60
W-110-B1 80 55 45
19 Gauge* 240 170 140
16 Gauge’ 240 170 140
’Different pairs should be spaced at least 1 inch apart to avoid crosstalk.
’One pair only used.
’Paper-insulated pairs with a capacitance of 0.062 pf per mile. When more than one pair is used, an appreciable increase in crosstalk may occur.
Figure 4.
TL50513
b. Cable Assembly CC-358 (spiral-four) will not transmit satisfaaorily above about 15-16 kc because of the loading. It is generally impossible, there
12
TO 11-368
Pars. 16-17
General
fore, to use it in circuits on which a carrier system with a top frequency of about 30 kc is superimposed. It is possible, however, to cover a short distance on the twin pair of Cable Assemblies CC-358, since the twin pair is not loaded by the coils in the connectors, or to cut off the connectors and coils and use the nonloaded side circuits, on a pair-per-pair basis as shown in figure 4. Parts of Cable Assemblies CC-368 could be used, since these do not contain loading coils.
17. LOADED INSULATED WIRES OR CABLE PAIRS.
a. When insulated twin pairs cannot be used, special loaded insulated wires or cable pairs may be used. Any such arrangement introduces some Irregularity, thus increasing the noise and crosstalk and reducing the return losses.
b. A suitable loaded arrangement for this purpose may be made by joining the connectors of a reel of spiral-four cable, as shown in figure 5. The cable is cut to give a section 210 feet long. At one cut end, connect one black and one white wire together as one conductor, and the other black and other white wire together as the other conductor. At the distant cut end, connect each white wire to the black wire with which it forms a continuous d-c loop.
I Connecting! Tractions! Cable Assemblies CC-358 J, Connect! ng| Wlres । including connectors wires '
I*-ennroi—I"----- 105 * --*! ---- 105 • ----• — 3’ —I
I approx. I i । , approx. I
yLlne protector Line protector i
_____I________cfi—a---------50—-STI 1
Open__,—S3---------------------------------22------vrs Open
S3-
L—j i___r i__
.Connectors
Bypass conductor 080 copper steel, or larger
NOTBS
1. *W* Indicates white or neutral insulation. "B" indicates black or colored insulation.
2. The line protector will be a Telephone Line Protector, 5 pair (If. X. No. 83-A protector mounting, equipped with No. 26 and 30 protector blocks, or the equivalent).
TL50514
Figure 5. Schematic circuit arrangement for loaded spiral-four inserts in open wire lines.
c. Such a loaded section is particularly subject to damage due to lightning picked up in the open wire. Each such intermediate section should be equipped with protectors at the last open wire crossarm on each side, the ground sides
13
TM 11-368 Tactical Open Wire
Pars. 17-18 Pole Line Construction
of the protectors on each side of the underground section being joined by means of 080 C-S or larger wires. One such bypass conductor should be provided for each open wire pair and should be kept close to the spiral-four cable (preferably taped to it every 4 or 5 feet), in the buried section or the section laid on the ground. Any slack in the spiral-four cable may be suspended on poles or other supports. In such cases, the bypass conductor need not follow the coiled cable and may therefore be shorter. When the loaded section is next to a repeater or converter, the end of the 080 C-S wires at the equipment should be connected to the equipment ground.
d. Such a loading section consists essentially of a series 3-millihenry loading coil, with a shunt capacitance of 0.0048 |if across each side of the coil. This capacitance includes that of any leads by which the coil is connected and that of Wire W-143 at the ends. This section might be improvised from two Cable Stubs CC-35.6 and suitable lengths of a pair in Cable WC-548 (the other pair remaining idle), or Wire W-143. When Wire W-143 is used, a turnover splice should be made at the center of the wire on each side of the loading coil to reduce the noise.
18. GROUND RETURN CIRCUITS.
a. Under certain conditions a single wire may be used as a talking circuit, the ground providing the return path. Such circuits are likely to be noisy, may crosstalk into other circuits on the same line, and can easily be intercepted at some distance from the line.
Approximate attenuations of ground-return circuits
Attenuation — dh per mile
Description 1 kc 8 kc 11 kc 20 kc 30 kc
104 Copper (on insulators — dry weather) 0.06 0A1 0.22 0.35 0.5
080 Copper-steel (on insulators — dry weather) 0.19 0.3 0.35 0.5 0.6
109 Steel (galvanized) (on insulators — dry weather) 0.25 0.8 0.95 1.4 1.7
W-110-B Pair (laid on ground — dry weather) 1.0 2.4 3.0 —
W-110-B (laid on ground — wet weather) 1.5 3.3 4.3
NOTE: The above figures are based on very limited data. They assume good
ground connections at each end, which may be difficult to obtain. In wet weather, the attenuation will generally be higher, but the loss due to the ground resistance may be less.
TL50524
Figure 6.
14
TM 11-368
Pars. 18-19
General
b. Figure 6 shows the approximate attenuation of certain ground-return circuits of this type with good grounds at the terminals. The attenuation will vary somewhat with the ground resistivity along the route, with the height above ground of the wire, with the type of insulators used, etc. It will often be found that the attenuation characteristic "wobbles” with frequency.
c. The loss of such circuits depends upon the ground resistance at the terminals and at intermediate points. Additional losses of at least 5 to 10-db over those computed frdm figure 6 may be obtained when poor ground connections are made at the circuit terminals.
SECTION III
Transposition Arrangements
19. GENERAL.
a. Tactical open wire construction is designed to permit the use of four carrier telephone channels on each pair. This permits a large saving of material and construction time as compared to the use of only one voice-frequency channel per pair. However, increased care in pole line construction is required to permit the use of carrier-frequency currents, which tend to spread over all the wires on the line and to cause too much crosstalk between circuits.
b. The primary means of crosstalk control are the transposition arrangements. A transposition consists merely of turning the pair over; that is, putting the wire that was on the odd-numbered pin on the even-numbered pin, and vice versa. If there were no transpositions in the line, the electric and magnetic fields produced by the telephone currents would cause conversations on different circuits to be badly mingled. The chief purpose of transpositions is to cause the crosstalk currents from one part of the line to oppose those from other parts, thus cancelling a large part of the crosstalk current at the ends of the line. When high frequencies are used, frequent transpositions are needed, because the talking currents become weaker, and are delayed in time as they pass along the circuit. The cancelling action of the transpositions therefore must occur at short intervals.
c. To obtain good cancellation, the crosstalk currents that are set in opposition to each other by the transpositions must come from line sections that are almost alike. The line construction, therefore, must be regular within certain limits. These limitations principally concern the accuracy of installing and checking the transpositions, the spacing of the transposition poles, the regularity of the wire spacing (and therefore the uniformity of the sag in the different line wires), and the minimum use of rubber-insulated or lead.-covered paper-
15
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 19-21
7 G
4-pin crossarm obtained busawing CrossarmPF32A in half.
TL505I5
Figure 7. Numbering of pin positions.
insulated wires on the pole line, either as additional circuits attached to the pole line or as substitutes for parts of the open wire itself. The limitations needed to minimize crosstalk are stated in the appropriate places in this manual. It is essential to check transpositions with great care and to correct errors. If this is not done, crosstalk coupling several times as large as with correct transpositions is likely to result. Regularity in construction also helps in controlling noise.
20. NUMBERING OF PIN POSITIONS. In a single-crossarm line the pin positions on the crossarm are numbered 1-2, 3-4, 7-8, and 9-10, from left to right when facing in the direction of the line trend. If a second crossarm is added to the pole line, the pins on the second arm are numbered 11-12, 13-14, 17-18, and 19-20. If a 2-pair line is constructed, utilizing half a crossarm, the pin numbering from left to right will be 3-4 and 7-8. The pin numbering scheme is illustrated in figure 7.
21. TRANSPOSITIONS FOR 1-CROSSARM LINE.
a. The transpositions for the 1-crossarm line are shown in figure 8. The pin spacing is shown at the top of the drawing. The transpositions on each pair are
16
TM 11-3M
General Par. 21
indicated by crosses in the horizontal lines. The pin positions are given at the left of the drawing. Thus, the two top lines indicate the transpositions for pair 1-2, etc. Note that the transpositions for each pair occur at uniform intervals and repeat regularly in a continuous succession. This simple plan helps in installing and checking transpositions. The only exception to this is that at every 32d transposition pole (about 3.6 miles) a transposition is omitted in pair 1-2 and one is added in pair 9-10. These points are known as S-poles.
b. The transposition points are indicated by the letters A, B, C, or S in the drawing. Every A-pole has one arrangement of transpositions, every B-pole another arrangement, etc. This aids in providing the proper insulators in each crossarm. Thus at an A-pole, an Insulator IN-128 will be placed on pin 8 to serve pair 7-8 only, and Insulators IN-15 on the other three pairs; at a B-pole, Insulators IN-128 will be placed on pins 1 and 10 to serve pairs 1-2 and 9-10, respectively; etc. In a transposition section of 32 transposition poles (about 3.6 miles), there are 16 A-poles, 8 B-poles, 7 C-poles, and 1 S-pole. The transposition arrangements were designed on the assumption that the average distance between transposition poles would not exceed 600 feet. The average spacing may be made less than this, but greater average spacing would result in serious increases in crosstalk. Poles with no transpositions on them will, of course, be placed between the transposition poles. When the pole span is changed from 150 to 200 feet, or vice versa, the spacing between transposition poles remains at 600 feet.
Pin spacing
Transposition poles OA8ACABACABACABACA8ACABACABACABASABACABAC etc.
^=ZG3G±ZGZCZCZGZZZCZCbiGZCZGZGZzb±ZZCZS 1ZZZZCZZZZZZZCZZZZZZZGZZZZZZZCZZZZZZZGZZZG
a_/CZ<_D<_Z>—/s——X——■—)■—
’ZZGZZZZZZZZZZZGZZZCZZZCZZZZZZZCZGZ|GZZp|qZ:
-----Full transposition section about i* miles --
Jois Notes:«. Nominal distance between transposition poles is eooft.
«. Tie wires to sides of insulators away from the pole.
TLS0516
Figure 8. Transpositions for first 4-pair crossarm.
17
TM 11-368
Pars. 21-23
Tactical Open Wire
Pole Line Construction
-16'
Pin spicing
Transposition poles
OABACABAOABACA.BADABACABAOABACABAS «tC.
'12 -3G___3G3G3G_____GG3G3G_____________3G3GDGZZDGZ
13 ----------------------------------.rxrx/-v-v-sz~
14 _^x /\------zx_--xzxzxz-x r~
20 _z|x-A^-X-A-z|x--zxJx^x--------- ,y--------------- X-zxjx_zx---A„
•-------Full transposition section about J» miles-•
Zero
pole
Notes J. For transpositions at S poles see fig io
2. Space crossarms * Feet
SFor transpositions In pairs i-t to »-io see fl^.a
4. Nominal distance between transposition poles Is aoo ft.
TL50517
Figure 9. Transpositions for second 4-patr crossarm.
c. No phantom transpositions are provided. One untransposed phantom, on pairs 3-4 and 7-8, may be used for short distances if it does not have too much line noise.
22. TRANSPOSITIONS FOR 2-PAIR LINE. The transpositions for the 2-pair line utilizing half a standard crossarm are the same as those for pairs 3-4 and 7-8 in figure 8. In this case the S-pole is the same as C-pole, and may be labelled C.
23. TRANSPOSITIONS FOR 2-CROSSARM LINE.
a. To control crosstalk the second crossarm is spaced 3 feet below the first arm. When the second arm is added, the transpositions on the first arm are not changed. The transpositions for the second crossarm are necessarily less simple than those for the first arm.
b. The transpositions for the second arm, at poles other than S-poles, are shown in figure 9. The notations on this drawing are similar to those on figure 8 for the first arm. (Every alternate C-pole is renamed a D-pole, since the second arm transpositions differ at these points.) The transpositions at S-poles are shown in figure 10. Remember that S-poles occur every 3 2d transposition pole (about 3.6 miles). On the first arm, the S-pole transpositions are all alike; but
18
TM 11-368
Pars. 23-24
General
I - 2 ----------------- ■-- ---1---+------ ---- --4----------- ---- ---+----4------------------------+
3-4 j:---)!----H---J!----IE--if---;E---If---iE---St---Ji---Ir---If---If---If---if---if---if---K
7-8 -------------------------------------------------------------'*---------"---------*--------------
9- IO ----iE--iE---if---if----iE--it---if---:f---:f---if---if---Ef---if---if---if---Er---if---if--if
11-12 -----If--- ----if--- ----if--if---it---if---if---if---if---------if--if---if---it---------if---
/
13-14 ----------if-----------------if--------if---------if------------------it--------it--------i----
17-18 -----------------------------------------------------------------------------------------------
19-20 -----—i E------f--------------|----$-------- ------|---*--------- ----7----1------ -- ----T----
z-*0 SI 32 SI S3 SI 32 St 52 SI 32 SI S3 SI 32 SI 32 SI 32 SI «tC.
W0 PI5 20 A ®>
2?+33 '7° P14 25' 22 AA V ■ ■ ill
25+93 ™ PI3 25' 2.2 M M >_ Illi 1
I 23+93 190 PIT 20' C V
205 21+99 PH 20- ®
19+H iU0 PIO 20‘
l7+9« 190 P9 20’ A ——„ I
15+99 210 Pi 25' 2.1
13+9? P7 25' llM-ftf.
11+93 105 P6 20 B ® >1 1
9+73 710 P5 20'
7 +49 115 P4 10' ® 1
S+99 150 P3 20' A ® till 1
4 +00 197 P2 20 ©
1 +95 10& PI 20' * 1 ® Illi 1
0+00 195 P0 20' 6M ?_50‘ „
\L I i TL-50521 III I
Figure 13. Form of notes to be kept by the pilot.
sketch. This record, kept carefully, will provide immediate orientation in case of question at any point in the layout work. Figure 13 shows a suggested form of data sheet which is simple and concise. Note that the first column shows cumulative length of line; the second, span lengths; the third, pole numbers; the fourth, pole lengths; the fifth, transpositions and guys; and the sixth, supplementary notes. Such data will be of great value both during and after layout. The notes must be complete and accurate.
58. SPECIAL PROBLEMS IN LINE LAYOUT.
a. Normal Spans over Rivers and Other Crossings. Where the line crosses watercourses, roads, railways, etc., pole locations will be adjusted to provide span lengths within the usual limitations and with good conditions for pole setting and guying on each side of the crossing. If possible, spans crossing railways should be limited to 150-foot maximum length for all types of construction. For lines with nominal 200-foot spacing, this will require that an
37
TM 11-368 Tactical Open Wire
Pars. 58-60 Pole Line Construction
adjustment of adjacent spans be made to keep the transposition pole spacing within the specified limits. Avoid pole locations on embankments which may wash away. Near watercourses, poles should be set far enough from the banks to be reasonably safe from washouts due to banks being cut away by high water. At road and rail crossings, select the pole locations on high ground to improve vertical clearances (par. 73c) if there is any choice. Poles should not be located closer to highways and railroads than indicated in paragraph 73b.
b. Long Spans. Where wide rivers, chasms, or other obstacles are to be crossed, special construction will be required. The line layout crew will select and stake the approximate location for long span supports and resume layout beyond the obstacle. The pilot will estimate the long span length, determine and record in his notes the number of normal span lengths included in the long span, and assign a correspondingly higher pole number to the far side support stake. For example, if a 450-foot crossing is encountered, and 150-foot spacing is being used, 2 succeeding pole numbers will be discarded and the far side stake will carry a pole number 3 units higher than the near side stake.
c. Repeater Locations. (1) Repeater locations will have been indicated either generally or specifically by the signal officer. If only a general location has been specified, it will be preferable from a transmission standpoint to locate the repeater at the end of a normal transposition section (S-pole). Whatever the location of the repeater, a new transposition section will be started at the far side of the repeater. Since there are usually two dead-end supports at a repeater {one on each side) the first support beyond the repeater will correspond to a zero pole and will be given a fractional number Vz higher than the support immediately preceding the repeater.
(2 ) To aid in preventing crosstalk around repeaters, the open wire connected to the A side of a repeater should not go on the same pole or poles as that connected to the B side. If the open wire lines connected to the two sides of the repeater follow the same route for a part of their length, they should be separated by at least the width of a road.
59. LOCATING POLES WHERE CHANGES IN GRADE OCCUR. Changes in grade will be kept within the limits given in paragraph 85. The line layout crew should be equipped with ranging poles for measuring changes in grade by one of the methods described in paragraphs 86 and 87. It may be necessary to adjust pole locations or make minor alterations in the route to obtain grade changes within the required limits.
60. PROCEDURE WHEN TWO OR MORE LAYOUT CREWS ARE USED. If a line route has been divided into sections to speed layout and construction, it is extremely doubtful that the survey will provide sufficiently accurate measurements to insure that the division points will correspond to whole transposi-38
Planning Tactical TM 11-368
Open Wire Pole Lines Par. 60
tion sections. If wire stringing were to be undertaken at an intermediate point in the line before layout was complete from the origin to such intermediate point, short transposition sections or other less satisfactory adjustments where the two pieces of line are joined would often be necessary. Such breaks in the regularity of the transposition section pattern are to be avoided. By observing the following method, the continuity of the transposition pattern can be maintained and the pole location stakes will be numbered consecutively throughout the length of the line:
a. The pilot and layout crew starting from the origin of the line should proceed with their work in the regular manner.
b. The pilot or pilots and layout crew or crews, who are to start farther along the line, should begin work at the predetermined location and proceed to stake out pole locations in the usual manner. However, pole numbers and transposition letters are not placed on the face of the stake toward the zero pole. Line number, pole height, and guy and corner information are provided on the stake in the proper location (par. 56). This pilot should pencil his own pole number series on the other face of the stake, starting with No. 1. This measure is taken to assist in keeping the usual layout data in the field notes (par. 57).
c. When the pilot who started at the origin of the line arrives at the beginning of the next pilot’s section, he will make such adjustments in span lengths as are necessary to join the two series of line stakes without exceeding the usual pole spacing limitations.
d. The pilot who started at the origin of the line then proceeds along the next pilot’s section of line and marks all stakes serially, on the face toward the zero pole, extending his own numbering system for the purpose. In addition, he will mark the stakes with proper transposition letters, continuing the pattern established in his own section. Since this pilot will probably have no further need for his layout crew, except possibly an assistant, the crew may be directed to return from the junction point to their base.
e. If the pilot who is numbering stakes serially overtakes the advance layout crew, he will arrange for the advance pilot to pick up the numbering and transposition system and carry it on, unless he is ordered to cover the entire line or follow other specified procedure.
j. The foregoing procedure will be used at the junctions of all pilots’ sections. When the layout is complete, therefore, the entire staking system will be consecutively numbered and marked with the transposition letters in a continuous regular pattern from origin to destination.
g. If the first layout crew completes its part of the line before the next crew starts, a prominent marker will be left at the junction point. If there is an incomplete transposition section at the end of the line, a note will be provided to instruct the next pilot on its completion. This note should give the location
808878 O—44
4
39
TM 11-368 Tactical Open Wire
Pars. 60-64 Pole Line Construction
of the last stake placed, with reference to the preceding S-pole. The pilot of the succeeding layout crew will pick up the numbering and transposition marking from the last stake placed by the preceding crew and will continue them through his part of the line.
61. CLEARING RIGHT-OF-WAY. Layout crews should not be expected to undertake major right-of-way clearing duties. However, they should be prepared to cut through small patches of brush or thicket, trim out interfering tree limbs, cut down embankments, and remove large stones, logs, and the like to provide for the passage of vehicles and to expedite their own work. Major right-of-way preparations will be assigned to work crews organized for the purpose.
62. TOOLS AND EQUIPMENT REQUIRED BY THE LAYOUT CREW.
The tools and equipment needed by the line layout crew will be similar to those recommended for use in surveying the route (par. 43), except for the addition of hand tools for use in clearing right-of-way. The supply of stakes should be ample for the proposed work and may be calculated at about 50 per mile. To minimize splitting, a wooden or composition mallet is the preferred tool for driving Wooden stakes.
SECTION IV
Symbols and Abbreviations
63. GENERAL. This section gives the abbreviations and general symbols which are suitable for use in the preparation and interpretation of written material, data, sketches, plans, and route maps for open wire lines. A further listing of authorized symbols and diagrams pertaining to wire communication is contained in TM 11-462, and additional symbols authorized for military use are given in FM 21-30. Other symbols may be used where necessary, provided they do not conflict with authorized symbols and are accompanied by an explanation under the heading Special Legend.
64. WIRE AND STRAND MATERIALS.
Material Diameter (mil) Abbreviation
Copper wire. 104 104 CU
Copper-steel wire. 080 080 C-S
Copper-steel wire. 104 104 C-S
Galvanized steel wire. 109 109 GS
2,200-pound strand. — 2.2 M
6,000-pound strand. — 6M
40
Planning Tactical TM 11-368
Open Wire Pole Lines Pars. 6S-66
65. TYPE OF WIRE AND CABLE.
Material. Abbreviation
Open wire. O W
Field wire. FW
Drop wire. D W
Field cable. FC
Spiral-four cable. S4
Lead-covered cable. LC
NOTE: Where applicable and desirable add, as follows:
A for aerial, as FCA
LCA
U for underground (usually buried), as FWU
S4U
G for on the ground, as S4G
66. LINE ROUTE MAP SYMBOLS.
Meaning Symbol
Wire line, on ground. ■
Wire line, buried or underground. —U ...........-... ....l>
Wire line, aerial (on overhead supports ).
1111111111 s111J111111111II111
Line to be removed.
TL-50523
NOTE: The number of physical pairs in a wire line may be indicated by a small number placed on the line. Additional appropriate designations of wire or cable types, sizes, materials, and equipment may also be given. Examples of numbers and their symbols are as follows:
41
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 66-67
Meaning
Symbol
4 pair 080 copper-steel open wire.
4 (080 C-S)
11 1111 i I 11 11 1111111 11111111
Field wire (2 pairs) on ground.
2 FW
Spiral-four cable, buried.
■H-
Repeater.
Terminal.
Test point.
67. SUPPORTS.
Type of support
Round timber pole.
4x4 support of sawed lumber.
X-frame.
Pole support and length of pole (20 feet).
Pole to be placed with an extension fixture to obtain greater height than provided by standard length pole.
H-fixture across the line.
TL-50525
Symbol
X
20*
&
111111111111
TL-50594
42
Planning Tactical
Open Wire Pole Lines
TM 11-368
Pars. 68-69
68. GUYS.
Tyft? of guy
Side guy using 2,200-pound strand.
"In line” guy.
11111 111 ll
1111111111
Symbol
Side guy to ground anchor (a) using 6,000- 1111111111 pound (6M) strand.
Guy to tree (Tr).
Hill HUI
TR
Guy to rock bolt (RB) using 109 steel Hill Hill wire (109 GS). Tl-50648
11II11 III I
6 M
R B
69. SYMBOLS FOR USE ON LINE STAKES. These symbols are to be placed on the stake in the sequence listed.
Line number and direction change, if any.
102
OR 116
Pole (or stake) serial number.
Type of transposition.
Special pole length and type.
321
8
®
I - 2.2M
TL-50649
Number and size of guys.
43
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 70
70. MISCELLANEOUS ABBREVIATIONS.
Bell System Practice. BSP
Gauge. Ga
Pair. Pr
Telephone (small circle). 0
44
CHAPTER 3
ENGINEERING REQUIREMENTS
71. GENERAL. This section covers general engineering requirements for tactical open wire lines. Terms peculiar to aerial line construction are defined; methods of measuring such characteristics as sag, pull, and change in grade are described; and the principles involved in guying are explained.
72. SPAN LENGTH.
a. Span length is defined schematically in figure 14.
b. To conform to different types of construction and storm loading, two basic lengths of spans, 150 feet and 200 feet, have been provided. The lengths of spans which should be used with sawed timber and round pole construction in the various loading areas are given in figure 2. Under ordinary conditions, an occasional span may exceed the basic length by 50 percent without special construction. Therefore, when the normal pole spacing is 150 feet, the limit of such an extended span would be 225 feet, and in 200-foot span construction, 300 feet. Aside from decreasing the factor of safety of the line, these extended spans increase the likelihood of swinging wire contacts. Therefore, such extended spans should be avoided by following a more favorable route if possible. Should trouble from swinging wire contacts develop in any extended span, a 16-inch separation between wires of a pair should be provided in that span by adding a crossarm at each end and placing only 2 pairs on each crossarm. In this case, the pair on pins 1-2 should go to pins 2-3, and the pair on pins 9-10 to pins 8-9. The pair on pins 3-4 should go to pins 12-13 on the second crossarm, spaced at least 3 feet below the first, and the pair on pins 7-8 to pins 18-19.
c. When a span exceeds the normal length by 50 percent, it is advisable to use long-span construction of the type described in Bell System Practices G31.170. In these cases, the 16-inch separation between wires of a pair, mentioned above, should be used to minimize the possibility of swinging wire contacts. If a transposition point should fall well within such a span, the catenary type of construction provided in Bell System Practices G31.175 is a suitable, but difficult, method of taking care of the situation.
73. CLEARANCE REQUIREMENTS.
a. General. This paragraph gives the minimum clearances, both vertical and horizontal, that should be observed in constructing aetial lines. The vertical
45
clearances listed are those which should exist at a temperature of 60° F with no wind. Vertical clearances are defined schematically in figure 14. Since the sag in a conductor will vary with temperature (par. 74), this factor must be taken into account when placing the wire. In cases where it is impracticable to obtain the standard clearances, the officer in charge should specify the clearances to be observed.
b. Horizontal Clearances. The minimum horizontal clearances (separations) for communication poles and stubs follow.
(1) RAILROAD TRACKS. Poles, guy anchors, or other parts of line supporting structure will not be set less than 12. feet from the nearest rail of railroad lines. This applies to crossings over railroads and to wire lines paralleling railroads. Separations greater than the 12-foot minimum specified are extremely desirable, particularly when paralleling a railroad line. A vertical line dropped from the outer end of any extension fixture must not come closer than 8 feet to the nearest rail when the lead parallels a railroad. Lines should not be built in the vicinity of railroad yards or loading sidings.
46
TM 11-368 Tactical Open Wire
Par. 73 Pole Line Construction
----------Span length ---------
Clearance
On level
~~~~~----------
Clearance
tl5°526
Figure 14. Span length, sag, and clearance illustrated.
TM 11-368
Par. 73
Engineering Requirements
VERTICAL CLEARANCES
Minimum vertical
Location clearance Remarks
In open country 14 feet May be reduced to 8 feet when the line runs along a fence, if there is no possibility of vehicular cross traffic.
Along a highway — Qearance should be sufficient to clear the type of equipment likely to use the highway.
Over highways or driveways 18 feet —
Over railroads 27 feet —
Over waterways — As specified by the command. The clearance is dependent upon the types of craft that navigate the waterway.
Between communication circuits and all power circuits. 4 feet —
Between guys and adjacent power circuits. 2 feet A clearance greater than the 2-foot minimum is desirable.
Between nearest metal parts (such as crossarm bolts or guys) of communication and power circuits on same pole. 40 inches —
Between military communication lines and guys and those of other communication systems. 2 feet —
TL50527
Figure 15. Vertical clearances.
(2) HIGHWAYS. Whenever possible, maintain at least 100 yards separation between the pole line and any highway it parallels. This separation is desirable in order to avoid damage to the line by vehicles diverted from the highway, and by aerial attack on supply routes. In crossing highways, place all parts of crossing span line supports (including anchors, push braces, and guys) at least 10 feet from the usable road shoulders.
(3) POWER LINES. On account of the danger to personnel and because of the noise which might be induced in the communication circuits, do not place communication circuits in the proximity of electric power and light lines if it
47
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 73
can be avoided. Separation of Vfi mile is recommended between communication lines and power lines which they parallel. Except in an emergency, do not place communication circuits on pole lines carrying power circuits; if so placed, remove the communication circuits as soon as practicable.
c. Vertical Clearances. The vertical clearances of telephone wires and stub guys above ground or rails are given in figure 15. Vertical clearances are measured either at the center of the span, or at the point of least clearance between line wires and the traffic route or object to which the clearance refers.
Temperature
Span length (fat) Conductor 0°F 30°F 60°F 5>0°F
Sag (inches') Tension (pounds) Sag (inches) Tension (pounds) Sag (inches) Tension (pounds) Sag (inches) Tension (pounds)
080 C-S 24 125 24 100 34 75 5 55
104 C-S 24 230 24 185 34 140 5 100
100 104 CU 24 230 24 185 34 140 5 100
109 GS 24 225 24 180 34 135 5 95
080 C-S 34 125 44 100 54 75 8 55
104 C-S 34 230 44 185 54 140 8 100
125 104 CU 34 230 44 185 54 140 8 100
109 GS 34 225 44 180 54 135 8 95
080 C-S 44 125 6 100 • 8 75 114 55
104 C-S 44 230 6 185 8 140 114 100
150 104 CU 44 230 6 185 8 140 114 100
109 GS 44 225 6 180 8 135 114 95
080 C-S 64 125 84 100 . 11 75 154 55
104 C-S 64 230 84 185 11 140 154 100
175 104 CU 64 230 84 185 11 140 154 100
109 GS 64 225 84 180 11 135 154 95
080 C-S 84 125 104 100 144 75 204 55
104 C-S 84 230 104 185 144 140 204 100
200 104 CU 84 230 104 185 144 140 204 100
109 GS 84 225 104 180 144 135 204 95
080 C-S 104 125 134 100 18 75 254 55
104 C-S 104 230 134 185 18 140 254 100
225 104 CU 104 230 134 185 18 140 254 100
109 GS 104 225 134 180 18 135 254 95
TL50522
Figure 16. Table of bare wire sags and tensions, 150-foot nominal spans.
48
TM 11-368
Engineering Requirements Par. 74
74. SAG REQUIREMENTS. There is a definite relationship between the sags and tensions of suspended wires and cables. For a given span length and conductor size, the sag decreases as the tension increases. Tactical open wire lines are designed on the basis of different tension values for the basic 150-foot and 200-foot span lengths. For spans of 150 feet in lines using 4x4 sawed lumber poles or X-frames, the basic tension for 080 C-S wire is 75 pounds per wire at 60° F. For spans of 200 feet in lines supported by round poles, or using 4x4 sawed lumber poles in straight portions of the line and round poles at corners and dead-ends, and for spans’of 150 feet on round poles under extra heavy storm-loading conditions, the basic tension for 080 C-S wire is 150 pounds per wire at 60° F. Figures 16 and 17 give the tensions and sags to be used for the representative span lengths at various temperatures. The sags and corre-
Span length (feet) Temperature
Conductor 0°F 30°F 60°F 90°F
Sag (inches) Tension (pounds) Sag (inches) Tension (pounds) Sag (inches) Tension (pounds) Sag (inches) Tension (pounds)
080 C-S 1*4 200 14 175 1’4 150 24 125
104 C-S VA 365 14 320 1’4 280 24 230
100 104 CU VA 365 14 320 1’4 280 24 230
109 GS VA 355 14 310 1’4 270 24 220
080 C-S 3 200 34 175 4 150 5 125
104 C-S 3 365 34 320 4 280 5 230
150 104 CU 3 365 34 320 4 280 5 230
109 GS 3 355 34 310 4 270 5 220
080 C-S 200 6 175 7 150 84 125
104 C-S 54 365 6 320 7 280 8’4 230
200 104 CU 365 6 320 7 280 8’4 230
109 GS 54 355 6 310 7 270 84 220
080 C-S 84 200 94 175 11 150 134 125
104 C-S 84 365 94 320 11 280 134 230
250 104 CU 84 365 9’4 320 11 280 134 230
109 GS Wi 355 9’4 310 11 270 134 220
080 C-S 12*4 200 14 175 16 150 194 125
104 C-S 12*4 365 14 320 16 280 194 230
300 104 CU 124 365 14 320 16 280 194 230
109 GS 12*4 355 14 310 16 270 194 220
TL50528
Figure 17. Table of bare wire sags and tensions, 200-foot nominal spans.,
49
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 74
SAG AND TENSION TABLE FIELD WIRE AND SPIRAL-FOUR CABLE Temperature 90° F Tension (pounds) 120 65 25 120 65 25 120 65 25 120 65 25 TL50529
Sag (inches) 14 14 14 cm cm cm CM CM CM r—4 »—< 42 42 42
Ph 0 O \0 Tension (pounds) 125 70 30 125 70 30 125 70 30 125 70 30
Sag (inches) 13 13 13 CM CM CM 30 30 30 40 40 40
d oOf Tension (pounds) 130 70 30 130 70 30 130 70 30 o o o ff> h' CO
Sag (inches) XXX (N (N (N »—4 r—< r-4 20 20 20 00 00 00 CM CM CM O\ O\ O\ co m m
d o0 Tension (pounds) .135 75 30 135 75 30 135 75 30 135 75 30
Sag (inches) cm cm cm »—< r—< r-4 O\ O\ r—4 f—4 r-4 CM CM CM 37 37 37
Conductor S4 W-50 W-110-B S4 W-50 W-U0.B S4 W-50 W-110-B S4 W-50 W-110-B
Span Length (Feet) 100 125 o rH 175
Figure 18. Table of sags and tensions for insulated wire and cable.
50
TM 11-368
Par. 74-75
Engineering Requirements
spending tensions for various span lengths of spiral-four cable and field wire used with tactical open wire line construction are given in the table in figure 18. Sags for span lengths between those shown in the tables may be interpolated. For example, the sag of a 135-foot span of 080 C-S line wire at 60° F should be
_ 125 x (8 — 5Vz) -f- 5% = 6^2 inches.
75. OSCILLATION METHOD OF MEASURING SAG. The oscillation method of measuring sag makes use of the fact that there is a direct relation between sag and the natural period of oscillation of the wire or cable. This relation is independent of conductor size or material, and span length.
OSCILLATION TABLE (based on time in seconds for 10 oscillations)
Time (seconds) required for 10 returns of wave Sag (inches)
5.0 3
5.8 4
6.5 5
7.1 6
7.6 7
8.2 8
8.7 9
91 10
96 11
10.0 12
10.4 7 13
10.8 ) 14
11.2 15
11.5 16
11.9 17
12.2 18
12.6 19
12.9 20
13.2 21
13.5 22
13.8 23
14.1 24
14.4 25
T (Time in seconds for 10 returns) = 10 times the square root of the sag in feet. TL50530
Figure 19. Oscillation table (based on time in seconds for 10 oscillations) for use in measuring wire sags. 51
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 75-77
a. To measure the sag in a line wire by the oscillation method, strike die wire with the side of the hand near one support and count 10 complete oscillations, noting the elapsed time. A complete oscillation is a wave that travels to the far support and returns to the starting point. The time interval should preferably be measured with a stop watch, the watch being started as the blow is struck. The wave can be detected easily by holding the index finger lighdy on the wire at the point of origin. This permits strict attention to be paid to the watch.
b. The span in which the oscillation test is made should be of average length; the wire should not have a sleeve or joint in it and should not touch tree limbs
Line wires
3”one sheave block Z sheave blocks
TL5O53I
Sca/e LC-64, a 300pound spring sca/e
Figure 20. Method of applying measured tension to line wires.
or other objects, as these would introduce reflections. When the time in seconds required for 10 complete oscillations has been taken, the amount of sag is determined from the oscillation table in figure 19.
c. Always refer to figures 16, 17, or 18 to determine the proper sag for the temperature at the time the measurement is made.
76. TENSION METHOD OF MEASURING SAG. In this method, the tension is measured with Scale LC-64, a dynamometer, or spring balance of suitable range, such as an ice scale, in series with the tensioning blocks. The method of tensioning is illustrated in figure 20. The desired sag and corresponding tension are determined from the sag tables (figs. 16 and 17). The wire is then brought to the desired sag by applying the specified tension. Tensions intermediate to those shown can be interpolated by a method similar to that described in paragraph 74.
77. SIGHTING METHOD OF MEASURING SAG.
a. Wire sag may be measured by means of sag gauges, or "targets” hung on
52
TM 11-368
Par. 77
Engineering Requirements
Brace PF- 7('30') or equivaient
Convenient size machine boit
Convenient size machine boit with thumb nut. t/se of Jock washer on boit betweenp/ates is suggested
«
Dimension fines mag be mdde with paint, crayon, or by scoringsurface of gauge with hack saw or fi/e. The cross member shou/d be painted a bright co/or
TL50533
Figure 21. Sag gauge.
the crossarms at the ends of the span being checked. A sag gauge is shown in figure 21. An improvised sag gauge can be made from crossarm braces or thin pieces of wood.
b. (1) To measure tension by the sighting method (with the line wires lying on the crossarms) adjust two sag gauges so that the distance between the top of the cross member of the gauge and the top of the cfossarm is equal to the desired sag. Select an untransposed span about midway of the section being tensioned and mount one sag gauge on the crossarm at each end of the span. Place the gauges on the crossarm in such position that the sight can be taken from a convenient position on the pole. The sighting can be done more easily if the gauges are placed on the crossarms at different distances from the pole (fig. 22) so that the line of sight and the wire being observed are at an angle with each other.
(2 ) With the sag gauges in place, the man doing the sighting calls for tension to be applied until the lowest point in the line wire is slightly above the line of sight across the tops of the gauge cross members; that is, until he can see
53
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 77-78
Figure 22. Sighting method of measuring sag with sag gauges.
daylight under the wire. He then calls for the tension to be released slowly until the lowest point in the line wire just touches the line of sight across the tops of the gauge cross-members. The wire is then held at this tension and the operation is repeated on the remaining wires of the span. The sighting method of measuring sag is illustrated schematically in figure 22.
(3 ) This is a quick method for checking sags in an existing open wire line. The gauge should be set to take into account the distance from the top of the crossarm to the wire in the insulator groove.
78. ALLOWABLE SAG DIFFERENCES.
a. It is important that line wires be installed at approximately the specified sag. If the sag is much greater than that specified, swinging-wire contacts due to wind may result. Also, if the wires of a pair are not sagged nearly alike, excessive crosstalk and noise may be introduced.
b. For a 1-crossarm line, the maximum sag difference in any one pole span between the highest and lowest wires (at the middle of the span) should not exceed 5 inches. This maximum value of 5 inches should be approached in only a small percentage of cases.
c, For a 2-crossarm line, the maximum sag difference between the highest and lowest wires on a given crossarm, in any one span and as measured at the lowest point in the span, should not exceed 3x/k inches. There should be a very-small percentage of cases where this maximum value of 3^k inches is approached. The average sag of the wires on the first crossarm in a given span should equal as nearly as practicable, the average sag of the wires on the second crossarm of the same span.
d. The above limitations on sag differences are designed to produce satisfactory carrier-frequency performance. When carrier systems are not to be used, or when emergency conditions necessitate accepting poorer transmission conditions, somewhat greater sag differences can be tolerated.
54
TM 11-368
Par. 78
Engineering Requirements
608878 0—44—
55
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 79
79. GUYING: DEFINITIONS.
a. General. Poles may be subjected to stresses other than those imposed by the vertical load of the wires. High winds, storms, ice, changes in grade, dead-
Cornerpo/e
|()0 ft‘
_____________________
yhlsol/stdnce,infeet,ls the pull at the corner.
If obstructions donot permit measuringas shown above the following methods may be used.
o _________
' „ PM „
- [0°ft<
Pon np
Corner " ' poie
Pole iisoMs Pote^
TL50535
Figure 24. Methods of measuring pull of corners in the line.
56
TM 11-368
Par. 79
Engineering Requirements
ended line wires, and changes in the direction of the line are some of the factors that increase the stresses on a pole. It is therefore necessary to stabilize poles likely to be subjected to unbalanced loads. Guys or push braces are used for this purpose.
b. Lead and Height. The terms "lead” and "height” as applied to guys, are illustrated in figure 23. The ratio of lead to height, as = 414-° height 20 ft.
— 1.25, is one of the means by which the size of the guy is determined. When this ratio is less than 1, the stresses in the support and guy are unfavorable. Further, the smaller this ratio becomes, the more unfavorable become the stresses to which these members are subjected. Therefore, if it can be avoided the lead should never be less than the height. The lead-over-height ratio should be not less than 0.75; a ratio greater than 1.5 results in excessive length of guy and should be generally avoided.
Corner
f. Screwtyimietpoint
e
Front styht
Backsight
2. Take first sight u/onty this fine.
Front styht | $ Read you if "on scats
B
S.Take secondstyht efontythis fine.
TL50536
Figure 25. Method of using Pull Finder LC-45.
57
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 79-80
c. Pull. The pull at a comer pole is the distance in feet measured as illustrated in figure 24. Pull may also be measured by means of Pull Finder LC-45, as shown in figure 25.
80. TYPES OF GUYS AND PUSH BRACES. The various types of guy'j
used in open wire line construction are as follows:
a. Side Guy. A side guy is a guy placed in a direction transverse to t direction of the line which it supports (fig. 26).
b. Head Guy. A head guy is a guy which is placed in the direction of t line which it supports (fig. 26).
c. Anchor Guy. An anchor guy is a guy extended directly from a pt or stub to an anchorage in the ground.
d. Pole-to-Stub Guy. A pole-to-stub guy is a guy used for transferring t load supported by a pole to the top of a guy stub (fig. 23).
e. Pole-to-Pole Guy. A pole-to-pole guy is a guy used for transferring t load supported by one pole, to the base of another pole.
f. Storm Guy. Storm guys are guys placed for the purpose of stabilizii the line, particularly during periods of storm loading. Under normal conditio
TM 11-368
Pars. 80-81
Engineering Requirements
Figure 27. Two- and jour-way storm guys.
TL50538
these guys do not contribute materially to the support of the load. Generally, storm guys consist of two opposing side guys, sometimes supplemented by two opposing head guys. These are known as 2-way and 4-way storm guys, respectively. Figure 27 illustrates 2-way and 4-way storm guys Anchor guys, pole-to-pole guys, or pole-to-stub guys may serve as storm guys. Storm-guyed H-fixtures may also be employed to provide strong points in the line. Sizes of storm guys for various conditions are given in paragraph 83.
g. Push Braces. Push braces (figs. 28 and 29) are not classified as guys, but serve the same purpose by bracing against unbalanced loads, rather than pulling against them. Push braces are used only at corners where suitable locations or materials for anchors and guys are not available.
81. GUYING AND BRACING AT CORNERS AND DEAD-ENDS.
a. The importance of avoiding sharp corners is indicated by the following table. Note from the table that the load on a corner pole, at which there is a 30-foot pull is 60 percent of that at a dead-end pole; at a corner where the pull is 50 feet, the load on the pole equals that at a dead-end.
Pull (feet) Interior corner angle (degrees) Change in direction (degrees) Resultant force (percent of load at dead-end)
10 168 12 20
20 158 22 40
30 146 34 60
40 132 48 80
50 122 58 100
59
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 81
v " a •
; .’ •/ 'Zf/~—ddjr6'/machfnebo/t
< 'h ■■ - • f V jifk and 2%f square washers
■■ ' " . - / / /'r>'
z>* • i «>. ' I hr
■ - /. , ‘ / // 'K
• - "■ i ] 'i '’y
" - - * 4 - "" ’ '
5 ■ ' - - i, :‘f
v -ft ■' " 4
'■'»■’ ' fg ■» J T •-; --
•■ V/ ■• -x ///: , ’'• 1 -•'“ '>■ 'b':
’r"v , ’/// ' ' .. ’ d '. V .....' ■-:. ' /// ■..' ., Y-?
■-' "'■ :7//V-*
’ ■ ' ’ Half crossarm or 3ft length of r
'*^'r 4x4lumber secured with tex/O
• 4 'X<-' TW-"-* machine bolt.
Tjsepiaik or flat stone
to provide firm footing. TL5O539
Figure 28. Push brace for use with 4x4 pole.
6Q
TM 11-368
Par, 8 2
Engineering Requirements
bo not cut pole but frame brace to an approximate f/t of pole.
Attach brace under lowest arm /
Hole should be~ dug to reach
in rock
(Lengthen. cmssorm bolts Usek^sg. washers under nuts and heads of bolts
be used except in rock.
TL50540
Figure 29. Push brace for use with round pole.
61
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 81-83
Anchor
a" 7x
! J 3 Angle A should be
------7^\ /----1 approximately equal vJ------------------------! toartf/efi
Corner pole
O\
T L50541
Figure 30. Schematic diagram, guying at corners u here pull is less than 50 feet.
b. All corner poles should be guyed or provided with a push brace; all terminal poles or terminal H-fixtures should be head-guyed. A corner guy should be installed so that it bisects the external angle of the line at the corner pole (fig. 30). If the pull at a corner exceeds 50 feet, the construction will include two structures as shown in figure 31-
c. Where it is found impracticable to use a guy on a corner pole, a push brace should be installed on the inside of the corner. The push brace will bisect the internal corner angle. Both 4x4 and round poles equipped with push braces will also be ground-braced (fig. 28), if the pull is more than 10 feet. The ground brace prevents the butt of the pole from kicking out of the ground under load.
82. SIZES OF GUYS.
a. Single-Crossarm Lines. The number and sizes of guys required for various conditions in open wire pole line construction are shown in the table in figure 2.
b. Two-Crossarm Lines. In guying 2-crossarm lines add one 2.2M guy to the guying shown in figure 2 in all cases except at dead-ends. Two-crossarm line dead-ends require two 2.2M guys, one at each pole of the H-fixture, in a’ddition to those shown. When application of the foregoing rule results in three 2.2M guys at a pole or one member of an H-fixture, one 6M guy can be used instead. If three 2.2M guys are used, divide the load equally among them.
83. ADDITIONAL NOTES ON GUYING.
a. Corners having a pull greater than 50 feet should be made on two H-fixtures, each taking one-half the corner (fig. 31). Guy the outside pole of the H-fixture as if it were a single pole in the same location.
62
TM 11-361
Pars. 83-84
Engineering Requirements
x. x. \ \ \
X. x. \ x.x.
Guy bi sec ts tlsow
th/s ang/e /
Figure 31. Schematic diagram, guying at two-pole corners where pull is more than 50 feel.
b. All guys placed prior to the wire installation will be installed with just enough tension to remove slack, except in the case of raked poles. In this case, only enough tension to secure the specified rake will be applied.
c. Poles having top extension fixtures (fig. 61) will be 2-way storm-guyed in medium and heavy loading areas.
d. All lines in exposed locations subject to medium loading conditions will be 2-way storm-guyed at each fourth pole (fig. 27).
e. All lines in exposed locations subject to heavy loading conditions will be 4-way storm-guyed at each fourth pole (fig. 27).
/. In a single-crossarm line all storm guys on round poles will be 2.2M strand. When the line is a 2-crossarm line, 6M strand will be used for all storm guys. Storm guys on 4x4 poles will be 109 GS wire (par. 119).
g. Storm guys will be placed with just enough tension to remove slack in the guys.
84. PRECAUTIONS IN GUYING. Correct guying is one of the most important factors in the construction of open wire pole lines. Guys take up the unbalanced loads at corners and dead-ends and thus prevent line supports from overturning or pulling out of line. Line construction personnel are
63
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 84-85
expected to understand and observe the principles and practices of guying and particularly to give attention to the following:
a. Provide proper lead-over-height ratios (par. 79b). If the lead is too small with relation to the height, the vertical component of load on both pole and guy becomes excessive.
b. Make sure that anchors are placed so that corner guys bisect the external angle of the corner (par. 81). Even a small displacement of the anchor location will result in a substantial load unbalance.
c. Use the sizes of guys specified for given conditions (par. 82). Guys that are too light are likely to fail, and guys that are too heavy will waste material.
d. Make sure that guys are placed at all points where needed, but do not guy unnecessarily.
e. Pull guys up only enough to take out the slack They will be tightened by the wire load when the wires are put under tension.
85. GRADING THE LINE.
a. Lines will be graded in approaches to marked changes in ground contour and at river, highway, and railroad crossings, if the difference in height of points of attachments of the conductors at adjacent supports would cause excessive strain on the tie wires, insulators, pins, and crossarms.
b. When grading a line, the clearances specified in paragraph 73 must be maintained if the ground is suitable for the operation of tanks or other mobile equipment. When necessary to use longer supports in grading the line, the change can be made with fewer length poles if a rounded grade rather than a flat grade is used. This difference is illustrated in figure 32.
c. It is advantageous from the standpoint of clearance and requires fewer abnormally high supports if the supports are located on elevations rather than in depressions. This is desirable even though it introduces spans somewhat shorter or longer than the basic spans.
d. When abrupt changes in ground contour occur, the location or length of
0
t
i
Flat grade—px _ - '
^Rounded grads
,1 I JL
II ________I] I __
TL50543
Figure 32. Flat and round grades.
SUf at < cha PW
64
Engineering Requirements
tm u-ar.s Par.
& —---------UppM _________________
^’’’’^^
Change invade atpoie B” AB or BC
Alternative method where the attachments on three petes are ah at the same height above the ground.
/ Mark po/es at D,F,andIF, a/i'at same height above ground, that
is, AD=BF=CD’.
2 Sight along iine b'fand mark pointE, or sight along OF and'mark f1 Change in grade at pole B"
_ DEor 1FE' TU50544
AB or BC
Figure 33. Measuring change in grade at up-pull in line.
supports can usually be adjusted to avoid concentrating the line grade change at one point. If changes in support locations are made, however, compensating changes should be made in an adjacent span so as to maintain the correct transposition spacing.
65
Tactical Open Wire
Pole Line Construction
TO 11-368
Fars. 35-87
e. It is recommended that changes in grade be limited to a maximum of 15 percent of the actual span length. This limitation in grade change is designed to relieve excessive vertical stresses on the supports.
86. MEASURING CHANGE IN GRADE: USUAL METHOD.
a. General. Changes in grade are measured either on ranging poles or on the line poles. In laying out lines, the ranging pole method of measuring change in grade will be used. For checking change in grade in a line under construction, or a completed line, the line pole method will be useful. In the following description of methods of measuring change in grade, it is assumed that the attachments to all supports will be made at a uniform distance from the tops of the structures. If these distances are to be different in any case, suitable
Change in
Change in grade on pole Eh \
gradecnpoteB^ \
'\ 'i-------------T /
\d_____________ o____________g/
A C TL50545
Figure 34. Measuring change in grade at down-pull in line.
allowances should be made in selecting the points on the ranging poles or line poles when sighting. Note that in«the majority of cases the measurement of the change in grade is read at the adjacent stake or pole rather than at the point where the change in grade of the line will occur.
b. Up-pull. The change in grade at up-pulls may be measured as shown in figure 33.
c. Down-pull. At down-pulls, the change in grade may be measured as follows: (1) Locate points D, O, and D1 on poles A, B, and C, respectively (fig. 34) at same distance from top of each support. Select points D and D1 on poles A and C so that there is a clear line of sight past point O on pole B to points E1 and E on poles C and A, respectively.
(2 ) Measure either distance DE or D1E1; the result multiplied by 100 and divided by the adjacent span length equals the change in grade in percent.
87. MEASURING CHANGE IN GRADE: ALTERNATIVE METHOD. Over rough terrain and where long spans are used, it may be difficult or imprac-66
TM 11-368
Engineering Requirements Par. 87
ticable to determine the change in grade by sighting on structures or ranging poles at A, B, and C only. In such cases, the following alternative method of measuring change in grade may be used to advantage.
a. Place one ranging pole at each proposed support location, A, B, and C (fig. 35 ). Ten feet from B, toward and in line with C, place a ranging pole at R. All ranging poles should be held vertically, and the bottom of each ranging pole at A, B, and C should be approximately at the location of the support to be set. The man at pole R should be in charge.
b. Let the man at A sight at corresponding points, such as the 5-foot marks on A and B, and locate point D where the line of sight strikes R. The man at R can locate this point in accordance with directions from the man at A.
IDown-j,
A II
I
Points 4 6 andfi shot/idbe ot same height above ground; that M
is,AF=BG=Cfi.
Change /n grade al B-}
1 IM
Figure 33. Method of measuring change in grade with four ranging poles.
67
Tactical Open Wlr®
Foie Line Conntructiitn
'OS 11-368
Par. 87___
c. Let the man at B sight through the same points (5 foot mark) on B and C and locate point E where the line of sight at B strikes R. The distance DE -4- X (10 feet) equals the change in grade at B.
d. If the change in grade, as measured by the foregoing method, is found to exceed 15 percent, a part of the change in grade can be transferred to the adjacent pole in each direction by placing a short line pole at the point of downward break in grade, or a long one where there is a sharp upward change. The effect on the grade change of such a difference in pole length can be judged by picking the sighting point G on ranging pole B as many feet lower or higher than the points F and II on ranging poles A and C as the line pole is shorter or longer, respectively, than those on either side. For example, if the line pole to be used at B is 5 feet shorter than those at A and C, the sighting point G, on B, is taken at a point 5 feet lower than points F and H on ranging poles A and C. Having established the three sighting points in this manner, the change
in grade with the shorter line R as before.
DE
pole at B will be DE being measured on 2k
68
CHAPTER 4 CONSTRUCTING TACTICAL OPEN WIRE POLE LINES
SECTION I
Organizing the Line Construction Project
88. PLAN OF THE PROJECT. Just as open wire lines must be planned properly, the organization of the project must be planned with equal thoroughness. Therefore the men responsible for organizing and directing construction personnel must take a broad view of the job in deciding how the work can be done most efficiently. Each project must be considered as an individual problem. It must be planned on the basis of its particular requirements. An open wire line cannot be expected to perform its function satisfactorily if it is thrown together hurriedly without proper attention to structural stability and good electrical performance. Good workmanship is necessary in building good open wire lines. At the same time, experienced workmen often find it possible to improvise within the intent of established requirements. Such action is encouraged when it aids in establishing service more quickly.
89. SEQUENCE OF OPERATIONS.
a. After the pole locations have been marked, the recommended sequence of work operations in open wire line construction is as follows:
(1) Distribute poles and other line materials along the route.
(2) Dig holes for poles and anchors.
( 3 ) Equip, set, and guy poles or frames.
(4) String wire.
( 5 ) Sag, transpose, and tie line wire to insulators.
b. If it is advantageous, digging holes for poles and anchors may precede distribution of material. Some of the functions given in subparagraph (3) above, such as pole setting, also may be combined with distribution. Some of the functions described in subparagraphs (4) and (5) above may be combined.
c. When wire is strung and spliced in continuously, temporary test points should be established for testing the line up to the point of completion of a day’s work by a team. The testing is supervised by the officer or noncommissioned officer in charge of the team. Each team is responsible for turning out a completed section of line in operating condition for each period of work.
69
TM 11-368 Tactical Open Wire
Par. 90 Pole Line Construction
90. ORGANIZATION OF CREWS AND TEAMS.
a. Definitions. A construction crew consists of a leader and the number of men needed to carry out completely and efficiently any major subdivision of line construction work. A team is a complete line construction unit, composed of the number and variety of crews needed to build an open wire line. Both crews and teams may be varied in size to meet conditions.
b. Sizes of Crews and Tearns. Under average conditions, crews of about the following sizes, equipped with the indicated vehicles or equivalents, are suitable for a balanced team. The number of men indicated in each case includes the crew leader and chauffeurs.
(1) MATERIALS DISTRIBUTION CREW.
8 men 1 O truck, 234-ton, 6x6, cargo,
1 Trailer K-36 or K-37,
1 O truck, Va-ton, 4x4.
(2) HOLE DIGGING CREW
(a) Earth Borer Equipment Crew.
5 men 1 S Truck K-44-B, 134-ton (earth borer and pole
setter).
(b) Hand Digging Crew.
8 men 1 O truck, %-ton, 4x4, weapons carrier.
or 1 S Truck K-43, 134-ton (line construction with winch).
(3) POLE EQUIPPING, SETTING, AND GUYING CREW.
8 men 1 S Truck K-43, 134-ton (line construction with
winch),
or 1 O truck, 2 34-ton, 6x6, cargo.
(4) WIRE STRINGING CREW.
8 men 1 O truck, 34-ton, 4x4,
1 O truck, 2 34 -ton, 6x6, cargo,
or 1 S Truck K-43, 134-ton (line construction with winch),
1 Trailer K-36 and wire payout frame equipped with Reels RL-17-(&).
(5) WIRE TYING CREW.
8 men 1 O truck, 2 34-ton, 6x6, cargo,
or 1 S Truck K-43, 134-ton (line construction with winch).
70
Constructing Tactical TM 11-368
Open Wire Pole Lines Pars. 91-93
91. SPEED OF CONSTRUCTION. An experienced construction team, operating under favorable conditions, can complete two to three miles of open wire line per day. Where conditions warrant, several construction teams can work at the same time if the line is divided into separate sections for different teams, or if crews and equipment are combined into a single larger team. The use of a single larger team requires close coordination and supervision to avoid unwieldiness.
92. IMPORTANCE OF TEAMWORK. Smooth teamwork, both within and among the various crews, is of highest importance. Before a job is started, all crews should be thoroughly instructed in the planned procedure so that each man understands the work assignments. The key to efficiency is to balance the crews at all times so that assignments are carried forward in unison. The officer or noncommissioned officer in charge is responsible for maintaining this balance by shifting manpower or equipment to meet variations in the work load. Frequent interchange of crew personnel, particularly during training, provides valuable experience and generally results in improvement of workmanship, efficiency, and flexibility.
SECTION II
Signals For Use by Line Construction Personnel
93. VISUAL SIGNALS.
a. The system of visual signals used by line construction personnel is shown by the accompanying diagrams with brief descriptions.
b. The person signaling faces the person signaled, if signals are being transmitted directly from one to the other. Both take positions from which the view will not be obstructed by pedestrians or passing vehicles.
c. Obstructions or distances may require that the signals be relayed through intermediate signalmen. These intermediate signalmen assume positions that enable the person signaled to see the signal clearly. The intermediate signalmen should pay strict attention to the person from whom the signals are being received. Signals should not be relayed through more men than absolutely necessary, because relaying requires more time for transmission of the signal, and increases the chance of error.
d. Improvised signal flags frequently can be used to advantage if the distance over which signals are transmitted is great, or if visibility is low. A red danger flag should not be used for this purpose because it may confuse drivers of passing vehicles.
71
608878 0—44-----6
TM 11-368
Par. 93
Tactical Open Wire
Pole Line Construction
e. The visual signals and their significance are shown below.
Swing either arm, extended full length, in a repeated arc across front of body.
Swing either - arm, extended full length, in a repeated arc across front of body. Intend other arm horizontally in plane of body.
Extend either arm full length horizontally in plane of body, with palm to the front, and repeatedly execute vertical arc.
/) fl'll fl Tj
TLBOB47
Figure 36. "Go ahead."
TLSOS48 WI®'
Figure 37. "Go ahead slowly."
1 whU
1 w 1
TLBO548 vMlWr
Figure 38. "Back up."
72
TRI 11-368
Par. 93
Constructing Tactical
Open Wire Pele Lines
Figure 39. "Back up slowly."
Extend either arm full length horizontally in plane of body, with palm to the front, and repeatedly execute vertical arc. Extend other arm horizontally in plane of body.
Figure 40. "Stop."
Extend both arms full length above head, with palms to front.
TLSOBBS
Figure 41. "Up.1
Extend either arm horizontally in plane of body. Execute short swings with forearm upward and back to horizontal.
Tactical Open Wire
Pole Line Construction
TM 11-368
P®s% 93
Figure 42. "Down.”
TLBOBS4
Figure 43. "Hold.”
TLSOBB5
Figure 44. "Release” or "cut off.”
Extend either arm horizontally in plane of body. Execute short swings with arm, downward and back to horizontal.
Extend arms full length in plane of body to an angle of 45°.
Extend both forearms to horizontal position on one side of body. Swing forearms repeatedly in opposite directions in short vertical arcs.
74
TM 11-368
Pars. 93-95
Constructing Tactical
Open Wire Pole Lines
\W//
JI
TLSOBS6
Figure 45. "All O.K.”
HJ' i
■ 1 A; i
- directions at each naif iny point.
groundline
4
Figure 48. Method of making 4x4 pole from two 2x4’s.
TL50559
79
TM 11-368
Pars. 98-99
Tactical Open Wire
Pole Line Construction
crossarm. The top of the gain will be about 8 inches below the pole top. Drill a hole 11 inch in diameter in the center of the gain completely through the pole. Figure 49 B shows framing details for round poles. Preservative, if required, should be applied when framing these poles and allowed to dry for 12 hours before handling the poles.
e. Framing Commercial Poles. Poles furnished by commercial pole suppliers usually will be received already gained and drilled. The standard poles are slab-gained for a distance of 4^2 feet from the top, and two through-bolt holes are drilled for mounting crossarms. Standard slab gaining is illustrated in figure 49 A.
BH'7 I?’
,/i i Mi la t'fK '>• || 2,
rJ i
Figure 49. Framing details for round poles. TL50560
f. Preparing X-Frame Members. 2x4’s to be used as X-frame members are bored at the locations shown in figure 50, to accommodate assembly bolts. No other framing is necessary.
g. Framing H-Fixtures. H-fixtures are made with 4x4 poles or round poles, according to the type of line being built, because of the strength required where these fixtures are used. These fixtures consist of two poles set 48 inches apart across the line to permit the mounting of a crossarm between them (fig. 51).
99. DESCRIPTION OF CROSSARMS.
a. Crossarm PF-9 2-A. The standard crossarm for use in tactical open wire pole line construction is Crossarm PF-92-A (fig. 52). Crossarm PF-92-A is 334 inches by 434 inches in cross-seaion and 88 inches long. It is designed to support eight wires, two pairs on each side of the center. The crossarms are bored for eight Pins PF-59 as well as crossarm brace bolts and mounting bolts. Three mounting bolt holes are provided, one at the center and one 24 inches each side of the center. Thus, the crossarm is ready for use with poles, X-frames.
80
C&iistructing Tactical
Open Wire Pole Lines
TM 11-368
Par. 99
2\4'*30''stake
lF/eoc/ho/e for dr/ve hook, 6 "beLow crossarm
TL5056I
square washer
\ IFx 6"machine bolt
Hook PF-8/ for supporting spiral-four cable or insulated wire.
W-/45 (103 G 5) guy wire or equivalent. \
/ *
72 *44 carnage bolt
RO'overall 2x4
d‘x4"x 30' stake
^6 hole._
6* Prom top, or naif bent over
Figure 50. X-frame assembly.
81
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 99
y x 6” machinebo itwith square washer under ., \ \
head and under nut. \ \ \ V.
„ / ^ss^Brace PF-4
// 3/gx4 / i,‘Ki
XL gy carriagebo/t i'y
lagscfeF!j,|| z ■ *. 1 1'1 '
/^\ ' ,,' i TL50562
/ \ j' I’’ n1'.^
/ 2.2M Hz strand guy । v
Figure 51. H-fixture made with 4x4 poles.
and H-fixtures. This feature also makes it possible to saw the arm in two at the center bolt hole to provide two 4-pin crossarms (fig. 7).
b. Improvised Crossarms. If the standard crossarm is not available, a substitute arm can be made from a piece of 4x4 pole or from two 2x4’s nailed or bolted together and bored for pin and the required bolt holes in accordance with the dimensions given in figure 52. If 2x4’s are used they may be fastened together with twelve penny (12d) nails or %-inch by 4-inch carriage bolts. The interface between the two 2x4’s should be set in the vertical plane; that is, the pin holes should be bored with the lead screw of the bit in the crack between
T8',,,r; jfj
I t? ■! o i:i !!Q i|i o ft i| <> !|i -4—*-
--.^4"----X--------36i------- *
—12^-----18 ~
!! ° H oi! ii ' ;■ H ° 6 !: *uL
- " -----------86,f‘ - ‘ ■ J
Figure 52. Crossarm PF-92-A. TL50563
82
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Pars. 99-100
Use staple or bent nail to hold guy. .
/w7 Crossarm r~ 5t°y
r
wCl/'-4g X/'"- machine bo/t.
11 Fj/xtyl washer under head
11- •-^Tj/7 li I'17\/\ and nut.
djm Kk\
' U.! \ / \ \S/eevejoint
/6d. nai/ or^^~~^V~X11 \ \ \ /
equivalent I; I1 , \ \ \
Two 2xd-s nailed together Mil \ \\ I
or 4 x4 lumber "--* ' |i ' W
ij'|' W-/45 U03dS)guy\X ; Il wire or equivalent. \\
| | Side guy^/ \
• i,
'< i
ii TL50564
1
Figure 53. 4x4 pole equipped with side guy and cross arm stay.
the two pieces. The spacing of nails must be gauged so that pin holes can be bored in the proper locations without interference. Knots and knotholes, if present in the pieces selected for the crossarm, must not be adjacent to each other in the finished crossarm.
100. DESCRIPTION AND USE OF CROSSARM BRACES OR EQUIVALENTS. Crossarm braces need not be used on sawed lumber supports in straight portions of the line, since the mortise at the top of the pole provides a horizontal seat for the crossarm. However, a crossarm brace, or its equivalent, must
83
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 100-102
Figure 34. Insulator IN-13 (left) and Insulator IN-128 (right).
be used on the outside of all corners. The 20-inch galvanized steel crossarm Brace PF-4 is used, if available. If Brace PF-4 is not available, the equivalent may be improvised by the use of 109 GS wire (fig. 53). The wire is passed through the crossarm brace hole on the side of the crossarm outside the corner. The ends of the wire are brought around the pole, fastened together, and stapled or nailed to the pole at a point IV2 feet below the crossarm. The stay should be installed reasonably slack and adjusted to provide a level crossarm by twisting die stay wires together after the line wires are brought up to tension. Crossarm Brace PF-4 is used on all round poles.
101. DESCRIPTION OF INSULATORS AND INSULATOR PINS.
a. Insulators. (1) Two types of insulators are specified for use in the open wire pole line construction described in this manual. These are Insulator IN-15 and Insulator IN-128 (fig. 54). Insulator IN-15 is of the single-groove type. Insulator IN-128 is of the double-groove type for use at transposition points and at points where wires are dead-ended in two directions at a single crossarm.
(2) If Insulator IN-15 is not available, any commercial glass or porcelain insulator of similar size may be used if it fits the standard 8-inch wooden pin. However, the performance of the line may be impaired by such substitution. There is no suitable substitute double-groove insulator for use in place of Insulator IN-128.
b. Insulator Pins. The standard insulator pin for use in open wire construction is Pin PF-59. This is an 8-inch wooden pin having dimensions shown in figure 55.
102. DISTRIBUTING MATERIALS ALONG THE LINE.
a. General. (1) The materials distribution crew, equipped with suitable vehicles (par. 90), proceeds along the staked-out line, leaving a pole or sup-84
Constructing Tactical TM 11-368
Open Wire Pole Lines Par. 102
TMgFTT
Hl
_L® 4"
/ '■!'1
/ 4
/ ■■|,4 ■ 'i1!
J_______■_
TL50566
Figure 55. Pin PF-59 (insulator pin).
port materials, a crossarm with pins installed, hardware, insulators, anchor material, and such other items as may be required at each stake location. The allowable load of 4x4x2 O-foot poles, or equivalent X-frame members, for Trailer K-36 equipped with 7.50 x 20 tires, is about 65 poles. Trailer K-37 can handle about twice that number. About 20 Class 9 (20-foot) poles can be carried on Trailer K-36 and about 40 on Trailer K-37. Poles also may be carried in a 2 34-ton, 6x6, cargo truck. This size of truck will carry a maximum load of about 60 4x4 poles or approximately 15 20-foot Class 9 round poles. The latter poles will be placed in the truck body butt first and the load securely lashed down. Materials other than poles or supports are carried in the cargo space of a truck, if poles are handled on a trailer. Otherwise a second truck is needed, or the number of poles in the truck load must be reduced to provide capacity for the other line materials. The quantities of these materials in each load should be sufficient to equip the number of poles on the trailer.
(2) The materials distribution crew is instructed to leave special materials such as extra-length poles, swamp footings, long-span construction materials, additional poles for H-fixtures or push braces, etc. at certain locations. Thus these items may be included in the proper loads for distribution at the required points.
b. Distributing Poles and Frame Members. Poles should be laid on the ground parallel with the line, with the butt near the location stake. They should be laid consistently with the tops in the same direction from the location stakes; that is, pointing either toward the zero pole or toward the far end of the line. This will assist the assembly crew in identifying pin positions at transposition
85
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 102-103
poles. Frame members are laid out similarly, with the feet at the stake and the tops (identified by the bored holes) away from the stake in one direction of the line. Poles and frame members should be laid, not thrown, on the ground in order to prevent their being broken or cracked.
c. Distributing Other Materials. (1) At each location stake, the materials distribution crew leaves a crossarm with pins already nailed in place, a crossarm bolt and washers, the proper number and type of insulators, anchor material if the location stake indicates one or more anchors are to be placed, and any special materials called for by the location stake markings or other information. These materials are to be placed on the ground near the top end of the pole. Insulators must be handled with care to avoid breakage.
(2) The materials distribution crew, if directed, also handles the distribution of coils of wire at suitable intervals along the line. Otherwise, the wire laying crew maintains the wire supply.
(3) The number of insulators of each type to be left at each location in a 4-pair line is as follows:
A transposition poles
B, C, and S transposition poles
All other poles
1 Insulator IN-128
6 Insulators IN-15
2 Insulators IN-128
4 Insulators IN-15
8 Insulators IN-15
(4) If the line has more or less than four pairs, the leader of the distribution crew is provided with a copy or overlay of the approximate transposition drawing on which the pairs to be equipped are indicated. Thus he can determine the number and type of insulators to be left at each pole.
103. DIGGING POLE AND ANCHOR HOLES.
a. Pole Holes. Pole holes may be dug by earth borer equipment, or by hand with shovels or Augers LC-34. Digging crews are equipped with proper tools, according to the type of digging to be done. The use of earth borer equip ment is covered in TM 11-364, Truck K-44-B and Earth Borer Equipment HD. Holes dug by any method should be dug to the depths specified in figure 56. If holes of these depths cannot be dug exactly at the stake location, the holes may be shifted in line in either direction. Do not dig holes to the side of the staked line if any location along the line within 10 feet of the stake is suitable for digging. If the stake is removed from the ground when holes are dug, drive it back into the ground nearby to remain as a reference marker. Holes should not be dug in steep banks or on the banks of a stream where the soil may be washed away from the base of the pole. Dig holes of uniform diameter and of
86
TM 11-368
Par. 103
Constructing Tactical
Open Wire Pole Line*
Depth of setting for poles
Length and type of pole Depth of setting (ft)*
Average firm soil Sand Rock
20 feet, 4x4 334 334 234
20 feet, round 334 434 3
22 feet, round 4 434 3
25 feet, round 434 534 3
30 feet, round 5 6 334
35 feet, round 534 634 334
40 feet, round 6 7 4
*In sand and firm soil, set poles 1 foot deeper when a pole-top extension fixture is used.
Figure 56. TL50567
a size to permit the poles to be set freely and backfilled spoil to be tamped firmly from the bottom to the top of the hole.
b. Pole Holes in Wet Ground and Sand. (1) In swampy or other unstable wet ground, dig pole holes one foot deeper than specified for firm ground. If firm footings cannot otherwise be obtained, use swamp footings and braces of the type shown in figure 80 with normal depths of pole setting. The deeper setting, without swamp footings and braces, is preferable if 1 or 2 feet of firm foundation can be found at the bottom of the hole.
(2) In loose or light sandy soil and in very wet unstable ground where the earth caves or slides as the hole is dug, shore the walls with pieces of plank or other material. The plywood drums in which spiral-four cable is shipped, or oil drums with the ends knocked out, make good shoring material. The shoring is placed when the ground starts to slip or cave in and is pushed down as the hole is dug. It need not be removed before the hole is backfilled.
c. Anchor Holes. Anchor holes are dug either by hand or with earth borer equipment. In the latter case, the hole must be finished by hand. Make anchor holes for head guys 3 to 4 feet deep, and for side guys 234 feet deep; in either case, the holes should be somewhat deeper in loose soil. If two guys are attached to the same anchor, the setting depth should be increased by one foot. The side of the anchor hole toward the pole should be cut smooth in undisturbed earth to provide a good bearing surface for the anchor. A slight undercut in the wall of the hole toward the pole will often improve the anchor bearing. Use a digging bar to make a slanting cut to the anchor hole to accommodate the guy wire dr anchor rod. If anchor holes cannot be dug exactly at the loca-
O—*4---7
87
TM 11-368 Tactical Open Wire
Pars. 103-105 Pole Line Construction
Insulator IN-126
FrVfnjl Carr>crg6 boft
/ 4^ ^-——' lnsu,t>tor IN-15
•j $ y/
/ay surety [I j!' "=Ca==£S§S^r
rTjlIiy! TL5O568
Figure 57. Location of Insulators IN-128 on Crossarm PF-92-A.
tions staked by the layout crew, dig them as near such locations as possible and in line with the bisector of the angle. If the hole for a guyed pole must be dug at some location other than the staked one, shift the anchor hole correspondingly.
»
104. FUNCTIONS OF THE PLACING, ASSEMBLING, AND EQUIPPING CREW. The placing, assembling, and equipping crew sets and guys poles and X-frames, puts on insulators, and in general leaves the pole line ready for the wire stringing and tying crews. Members of the placing, assembling, and equipping crew will be provided with Lineman’s Equipment TE-21. Tool Equipment TE-27, sleeve pressing or rolling tools, and such miscellaneous construction tools as handlines, digging tools, tamping bars, a saw, and scaling ladders (par. 121) will be carried on the vehicle used by this crew. This vehicle will also carry the necessary construction materials to complete the work assigned to the crew. Extra crossarms will be carried to provide replacements for defective, broken, or damaged crossarms and for use as spare anchor material.
105. EQUIPPING CROSSARMS.
a. Placing Insulator Pins. Insert Pins PF-59 in all pin holes in Crossarm PF-92-A and fasten each pin with a 6d nail driven through the side of the crossarm and the shank of the pin allowing the nail head to project slightly. Drive the nails at the centerline of the arm. The placing and fastening of pins usually can be done more easily before the arms are distributed along the line.
b. Placing Insulators. Screw down Insulators IN-15 and IN-128 hand tight on the pins. Use figures 8, 9, and 10 as a guide in determining which pins to equip with double-groove insulators at transposition poles. Crossarms at intermediate (non transposition) poles are equipped with Insulators IN-15 throughout. Where transpositions occur, place Insulators IN-128 on pins 1, 3, 8, or 10 (the outside pin of the pair), as required, of pairs 1-2, 3-4, 7-8, and
88
Constructing Tactical TM 11-368
Open Wire Pole Lines Pars. 105-106
9-10, respectively, as shown in figure 57. Only one Insulator IN-128 is required for a pair of wires to be transposed at a transposition point. When double arms are used at transposition poles on heavy corners, place two Insulators IN-128 for each transposed pair to relieve the load on the pins (fig. 58). Equip pins of untransposed pairs with Insulators IN-15. If two crossarms of wire are being installed, follow a similar procedure on the correct pins of the lower arm, using figures 9 and 10 as a guide in determining the pairs to be transposed. The crossarm at transposition poles must not be reversed after insulators are in place, since this will cause Insulators IN-128 to be in the wrong pin positions.
c. Placing Cross arm Braces. Use a % by 4-inch carriage bolt to attach Brace PF-4 to each crossarm used with round poles and, if available, with 4x4 lumber poles used at corners. At corner poles, Brace PF-4 always is placed outside the corner. The crossarm, therefore, must not be reversed after the brace has been attached. At all H-fixtures, Brace PF-4 should be mounted as shown in figure 51.
106. ATTACHING CROSSARMS TO POLES AND X-FRAMES.
a. 4x4 Sawed Lumber Poles. (1) Before raising the pole, attach crossarms to 4x4 poles by means of a 34 by 6-inch machine bolt and nut. Use a 2 34-inch square washer under both the bolt head and the nut. Eleven-sixteenths-inch round washers may be substituted if square washers are not available. Place the nut on the crossarm side as shown in figures 53 and 57.
(2) To prevent reversal of arms in the course of assembly and setting, use a routine procedure in performing the various operations. A good method is to turn the pole so that the mortise or gain is up. Place a washer on the bolt and pass the bolt through the hole from the under side. Lower the crossarm on the bolt, making sure that the crossarm is not turned end for end. Place the upper washer and the nut on the bolt and tighten the nut.
(3) If Brace PF-4 is used, make sure that the crossarm is at right angles with the pole and fasten the lower end of the brace at the center of the pole by means of a % by 334-inch lag screw. If, on a corner pole, a wire stay (par. 100) is used in place of a crossarm brace, place and adjust the stay before erecting the pole.
( 4) If a transposition is required at a corner having a pull of more than 20 feet, install two crossarms on the corner H-fixture. Place one arm on each side of the H-fixture, as shown in figure 58. Machine bolts 12 inches long are required for the mounting of the arms. One arm is equipped with the arrangement of insulators and pins required by the particular type of transposition. On the second crossarm, install pins and Insulators IN-128 for the transposed pairs only. If 4x4 poles are used, the double-arming may be done before the H-fixture is erected. With round poles, it is advisable to set the poles before installing the crossarms.
89
TM 11-368 Tactical Open Wire
Par. 106 Pole Line Construction ,
\\ Z/z?e trertd
X. X. I
TL50569
Figure 58. Double-arming at corner transposition poles.
b. Round Poles. Attach crossarms to round poles in the same manner as to 4x4 sawed poles, using a % by 10-inch crossarm bolt. Standard round poles are slab-gained and required Brace PF-4 in all cases. Use a %- by 334-inch lag screw to fasten the crossarm brace at the center line of the pole.
c. X-Frames. Assemble X-frames by placing 34- by 434-inch carriage bolts through holes located 61 inches from the top ends of the 2x4’s (fig. 50). Place a square or round washer under the nut This part of the assembly can be performed at a depot or dump and the members collapsed for delivery. To attach the crossarm, spread the 2x4’s to make an X and pass 34- by 6-inch machine bolts through the holes in the ends of the 2x4’s and the holes located between pins 2 and 3 and pins 8 and 9 in the crossarm. Use square or round washers under the bolt heads and the nuts. Take the usual precautions to insure the proper location of transposition insulators. Reinforce X-frames at dead-ends and heavy corners as shown in figure 59.
d. Side Extension Arms. Occasionally it may be found desirable to set a pole slightly out of line to 'improve horizontal separation or avoid an obstacle. Poles may be set 2 feet out of line on either side of the line, without affecting the true course of the line wires, by the use of a side extension arm constructed as shown in figure 60.
e. Pole-Top' Extension Fixture. To provide greater pole height for added vertical clearance, a crossarm can be used to make a pole top extension fixture as shown in figure 61. This fixture provides about 5 feet of added height. Attach the assembly of pole-top extension fixture and crossarm to the pole before raising. Set poles with pole-top extension fixture 1 foot deeper than normal.
90
Constructing Tactical
Open Wire role Lines
TM 11-368
Par. 106
y ' Zq'7 n JL Secure eye of guy toty of fixture . witii staple dr bent
/W ~\:'~C/ampc PF- 6i
Temporary quy / y \
W-/45 (IO9Q5)~I /\>A \
orFandiine.'3^T / \IIU \ \
jj \ /w\
f// r —2.2M strand guys —A
\Sf \
’*' I TL50570
Figure 59. Reinforced X-frame for use at dead-ends and heavy corners.
91
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 107
G5)guy
#x6"machine boit ore^/ent
Place 2 Ft" square
under nut and head \ X1 •1 |1| I X X~
ofbolt \ . ■ .Ft-' i'M1 XX’
\ /iIXXC Id J14ft- XX Xx \ X< .
ziJ ZZZ \ . / lii I \
\Wl X
nZw8L_ w
x^^Xrr ■
Kxx" 2x4"/umber l'|(X
approx. 7 ft. iong. -i;; i j
J !;!> i'l ।
'X
i I '
! I 11
I ■
1'
I]'। j TL50571
Figure 60. Side extension arm.
107. ATTACHING GUYS TO 4X4 POLES.
a. Guys used with sawed lumber poles may be either 2.2M strand or 109 GS wire, depending upon the strength desired in the line and the angles of corners encountered (par. 82). Side guys will be made either of 2.2M strand or of doubled lengths of 109 GS wire as shown in figure 53. Head guys will be made of 2.2M strand.
92
TM 11-363
Par. 107
Constructing Tactical
Open Wire Pole Lines
%x4 "carriage bolt
fbx6"mqch.boft Use 2% square washer under nutandhead of bolt.
124
Poundpo/e
TL5O572
4 *4 sawedpa/e
Figure 61. Pole-top extension fixture, 4x4 and round poles.
One-half crossarm. used as support for lineman.
PF-92 A
Brace PF-4
Attach „ . braces with x 34 tag screw
Center mounting
Crossarm PF-92-A
r .Machine bolts hxB *40
Use z£ square washers under nuts and heads ofbo/ts.
93
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 107-108
3/ex34 lag screw below guy to prevent slipping
1 >!i
Approx, t/4 dia. of/oo/e.-
k \
* \\
H sX\
* ., (tlseP-bo/t C/amp
I | WL PF-6! w/th22M
! । Strand)
. ' J Clamp 6M strand
. 1 , FT-56
y \ TL50575
Figure 62. Wrap method of attaching guys.
b. In making head guys, form a loop approximately 1%: feet long at one end of the 2.2M strand with Clamp PF-61 set up tight. This loop or eye is slipped over the top of the pole and held in place with a nail or staple to prevent it from coming off while the pole is being erected. Where the lead-over-height ratio is about one to one, approximately 35 feet of strand is required for the guy.
c. When 109 GS wire is employed for side guys on 20-foot poles with a lead-over-height ratio of about one to one, approximately 60 feet of wire should be provided. This length of wire should be doubled on itself approximately 5 feet from center, making one leg 10 feet longer than the other. The doubling point in the guy wire is then passed around the pole top and over the crossarm on the side of the pole away from the anchor. A nail or staple is driven to hold this wrap of wire in place while the pole is being erected.
108. ATTACHING GUYS TO X-FRAMES AND 4x4 H-FIXTURES.
a. Guys used on X-frames are made of either 2.2M strand or 109 GS wire. Guys used on 4x4 H-fixtttres are made of 2.2M strand.
b. Dead-end guys for X-frames and H-fixtures are made from 2.2M strand. Two guys are required; each is made up in the same way as a 4x4 pole head guy. The eye or loop in the end of strand is slipped over the projecting top end of an X-frame or H-fixture leg and held in place with a nail or staple. In addition, dead-end X-frames require a temporary single guy of 109 GS wire, attached at the center bolt hole of the crossarm. An end of this wire is passed
94
TM 11-368
Pars. 108-109
Constructing Tactical
Open Wire role Lines
L ,;i 5/e xB'machine bo/t
ho/t th/mb/e-eye
2'4squaretiji washer I
1 1 1 vx's
|,| ‘Ji' VV C/ampFT-56
|i 'i ;1 \Z"v\/ 6M strand
'i' \•< .if'*' ।
\\ "" ’7-//
> A-
ume/ ’'WiiM <
Undercut 7 • Log or half
trenchF crossarm
fty /^Single loop of guy-wire
around anchor
20 d. nqils
Anchor assembly //
* ,,r >. i/l
|lfl: v /A/' /•
x .1^ ' /Z ixO'
1/' 4 fdJriTTr —
Undercut lh 1 < *
72 cross arm
or 2 x 4 x 3t^ ft.
TL50580
single loop of guy w/re
around anchor
Figure 69. Forms of anchors suitable for use with 4x4 poles.
101
TM 11-368
Par. 115
Tactical Open Wire
Pole Line Construction
Undercut \ trench so 'r. log will pul! ■'against solid "'earth.
J Vertical depth of setting
Cut away sap wood r under washer Screw t on as far as it will go.
Figure 70. Log (or pole section) anchor, set transversely.
TL50581
fH J&iiB
Hr
w
r BBS
<««
I diameter of
i„ the anchor g'
TL50583
^Wfag
Figure 72. Method of obtaining added bearing area, transverse log anchor.
bearing area required in materials to be used for anchors is 2 square feet. Forms of anchors suitable for use with 4x4 poles are shown in figure 69. Anchors for use with round poles are shown in figures 70, 71, 72, 73, and 74. Guys may also be attached to trees (figs. 75 and 76).
iih ,i F\i7 / Zfe 'X -yZ
- •'/■ ■ h II
7 TL505S4
Figure 73. Method of obtaining added bearing area, longitudinal log anchor.
(50X878 O—44------8
103
ill TM 11-368 Tactical Open Wire
ggH£ Par. 115 Pole Line Construction
(<5)
I Ma ;
I' ’ ’■ ■' fata1v m
I VAcAAiA
' a; ,■ A via
I " ■aa\2
- of 24' P,an^
Anchor Roa
. -■ G77“\‘4\
• /A / 7'1 \ TA
■-lixisy\^WW^®-' ^-^v-7?-XT
v/^3«Wx 20 plank
anchor
/// lag .. < Mi
Staple tree blocks to guy. u f/*
7qx3z Jag screw About twice diameter of tree,
used when necessary to \ prevent guy from pulling up. \
Use this method for wrapped guys on trees.
TL50587
Figure 76. Tree guy for round poles and for heavy corners, 4x4 poles.
b. Attaching Wire or Light-Strand Guys to Anchors. The 109 GS wire or 2.2M strand, used to guy 4x4 poles, is placed around the center of the anchor with the free end coming up from under the anchor. A staple Or bentover nail can be used to keep the guy centered on the anchor but it must not
106
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Par. 115
/st operation^ 2d operation I 3d operation
n J n r
$ J f Remove pulling j'
JB) / p <0 /1 apparatus and /
/S/ / / make up tail. /
ZJsPuU / J / ’I / !
ii / ji \ i /
r\ / I i/ / 1
/ / Place and\\ & /
< AZ ‘Jis /X tighten i| / ,|
/X/ i' Jj/ i! 7/
/J/^Strand J /t / h //
f pullers / C / j rd
JFl/ '* /Z7 ///
TL50588
Figure 77. Method of pulling up earth anchor guys.
be driven so deeply as to bind the guy wire on the anchor. The free end of the guy wire is pulled up until most of the slack is taken out of the standing part of the guy with the anchor on the bottom of the anchor hole and against the wall of the hole nearest the pole. The guy wire ends are spliced together, or the free end of 2.2M strand is held with Clamp PF-61. The anchor hole is backfilled and tamped. Each shovelful must be thoroughly tamped as it is backfilled.
c. Attaching Strand Guys to Anchor. Anchors to which it is intended to attach guys made of 6M strand and, in some cases, 2.2M strand, on round poles, must be equipped with Anchor Rods AH-4 inserted in 1J-inch holes drilled in the anchors. Patent anchors, if available, may be used and should be set in accordance with instructions given in TM 11-363. When two or more strand guys are to be attached to the same anchor, a separate anchor rod is required for each guy. Anchor rods are set in line with the point on the pole where the guy will be attached, so that when the guy is pulled up, the line of the pull is straight from anchor to the point of attachment on the pole. Pass the guy strand through the eye on the anchor rod and pull the guy up with strand pullers and rope blocks as shown in figure 77. Pull up guys at poles, stubs, or trees as
107
TM 11-368
Par. 115
Tactical Open Wire
Pole Line Construction
---------------------------------------r
shown in figure 78. Only enough tension will be applied to hold the pole top in the required position. Attach Clamp PF-61 or Clamp FT-56 as described in paragraph 109. A tail, 18 inches long, is allowed to extend beyond the clamp and is lashed to the standing part of the guy with several turns of 109 GS wire.
d. Wrap Method of Terminating Strand. Guy strand may be terminated by serving the individual wires of the tail around the standing part of the guy with pliers, as illustrated in figure 79- Each turn of wire must be drawn tightly and the pliers must be handled carefully to avoid nicking or breaking the wires as they are served. If this method is used to conserve a limited supply of guy
V -.-VAI ’• Gt rand puller or
1st operation-pull other approved device,
slack out of guy
V /•"£ diameter of stub
V i'dl ilil / operation- wrap guy
/ around stub and place and tighten
/ guy damp as shown.
i ' ll ■ bl __-------------------------------------------------
r yidr
V 3d operation-remove pulling
I apparatus and make up tail.
TL50589
Figure 78. Method of pulling up guys at poles, stubs, or trees.
108
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Par. 115
Grip wire firmly but do not cut or nick it before completing serving.
Untwist free end of strand to point where serving is to beg in. Draw each I turn of serving tight/y around assembly \ \of stranded and unstranded wire.
This may be done by hand in case \\of 2.2 m. strandand with cutting \\\edge of 8"pliers (TL-io7)incase
\ of 6 M. strand.
Excess wire may be removed with aid of 8"p/iers or hacksaw.
Completed termination
Alternative method
This methodofserving shou/dbe used when the special too! illustrated is available. tlsosso
Figure 79. Serving method of terminating strand.
109
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 115-117
clamps, apply it at the anchor ends of guys and use clamps at the pole ends. The guy clamp at the pole end will allow for guy adjustment. The extra length of guy strand will be provided at the pole end of the guy in this case.
7 5/3 "mach/hebo/i
/ \ w/th two square washers.
4'6'-)/ / / 2? * 4^” carr/atye
/ / / \ bo/t with square washer
/ / / 2 x 4 \74Mder nuE\
/ / / /umber \ \ /
k------------5'S‘'-^----—-----------------I
ipl t/se /2drads For hbbr/cat/on.
TL50591
Figure 80. Swamp footing fOr 4x4 or round poles.
e. Splicing Wire Guys. When a wire guy has been pulled up to the proper tension, cut the two ends of the wire so that a sleeve joint can be made (pars. 146 and 148). If sleeves and tools are not available, a Western Union joint will be made (par. 151).
116. GUYING LONG SPANS. The use of long spans is discussed in paragraph 72c. Poles at the ends of spans exceeding by 50 percent the basic span length for a given loading area (fig. 2) should be guyed in accordance with Bell System Practices G31.170.
117. SWAMP FOOTINGS. In swampy or other unstable ground it may be necessary to provide additional bearing area for supports. Figure 80 shows a method of constructing a swamp footing for either 4x4 or round poles. Addi
110
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Pars. 117-118
tional braces may be employed if required. Figure 81 shows a swamp footing for X-frames.
x3 mdch//K fiq •/ I Use2 *4 lumber and x. 12 d. nails.
J
\ -dl SIDEVIEW
■ .........'F"
TL5O592 *
Figure 81. S warnp footing for X-fram e.
118. ROCK ANCHORS.
a. If rock anchors are required for use with 109 GS guy wires, a satisfactory expedient, which makes use of materials usually available, is shown in figure 82. This anchor is shown with a single guy wire, but it is also suitable for use with a double guy of the type used with earth anchors.
b. Where rock anchors are required for strand attachments, the anchor is the same as shown in figure 82 except a 34 by 10-inch bolt is substituted. A loop is made in the strand by means of Gamp PF-61 or Gamp FT-56 as outlined in paragraph 107. The bolt is passed through the loop and wedged firmly
111
Tactical Open Wire
Pole Line Construction
TM 11-3G8
Pars. 118-120
2h square washer^
carriage bolt
Dr/// ho/e with
Figure 82. Improvised rock anchor.
'■Rock surface
-—
. 45~approx.
Wedge bolt in hole with small nails or pieces of tine wire.
TL50593
into the hole in the rock. The other end of the strand is then attached to the structure as described in paragraph 107, 108, or 109-
119. STORM GUYS. Storm guys are intended for use in medium and heavy loading areas. However, in light loading areas where strong or continuous winds are encountered, 2-way storm guys on every 10th pole will give the line additional strength and stability. Storm guys, when placed, should have just enough tension to remove the slack from the guy. A pole line having only one crossarm of wire will require 2.2M strand for storm guys. 6M strand will be employed on lines having two arms of wire. In medium loading areas, all lines in badly exposed locations should be 2-way storm-guyed at each fourth pole. In heavy loading areas, all lines in severely exposed locations should be 4-way storm-guyed at each fourth pole. Poles with pole-top extension fixtures should be 2-way storm-guyed in both medium and heavy loading areas.
120. HIGHWAY AND RAILROAD CROSSINGS.
a. Highway Crossings. (1) Provide at least 18 feet of vertical clearance at open wire crossings over highways. The poles used to provide this clearance, in order of preference, are: 25-foot round, poles, 20- or 22-foot round poles with an extension fixture (fig. 61), or poles fabricated from full-length 24-foot 2x4 lumber. The poles supporting the crossing span should be located on ground substantially at the level of the highway or somewhat higher, if possible.
(2) Guy the poles at each end of the crossing span as shown in figure 83. Two head guys, placed as shown, will provide both lateral and longitudinal
112
Constructing Tactical TM 11-368
Open Wire Pole Lines Pars. 120-121
stability for the crossing poles. Face the crossing poles away from the highway; that is, the crossarm should be on the side away from the highway.
b. Railroad Crossings. Since crossings over railways require a vertical clearance of at least 27 feet, high supports are needed. For a single-crossarm line, 3 5-foot poles are required. For a 2-crossarm line, 40-foot poles or 3 5-foot poles with an extension are needed. Whenever possible, poles of the required height should be obtained, as the alternative form of construction is a temporary underpass containing a special loaded section of spiral-four cable (par. 161). Crossings of the underpass type degrade the transmission appreciably and are to be avoided if at all possible. Crossings of electrified rail lines are to be avoided. If such crossings must be made, use rope slings of the type shown in figure 91- Take all possible precautions to carry out the work safely.
121. MAKING AND USING SCALING LADDERS.
a. The use of lineman’s climbers on 4x4 poles is dangerous and should not
60°to90
clearance at least/8 ft.
Equalize tension in guys whenmaking installation. Face crossarms away [from crossing
Head guys
Set poles between drainage ditch and fence line, usually nearer fence line.
PrF ^DjEloge shou/der a/ten
TL50595
Figure 83. Guying system for highway crossings.
113
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 121
be attempted. A scaling ladder, made as shown in figure 84, provides a satisfactory means of climbing 4x4 poles, H-fixtures and X-frames.
60d. no//
30 d. nail
***
Cutting line
fl
screws
Made from Brace PF-4 or
VjTjg equivalent strip stee/
For /adder materia/-se/ect a straight 2x4 as free from defects aspossible.
Ladder should be Inspected frequently to see that no weakness has developed
~pr that might he hazardous
A wrapping of wire or bunding iron may be placed around upper part of step ror reinforcement.
'tnL
3- 24"holes d/y/fed
Method of fabricating be fore angular cut 2 steps from a !2 " /ength fo made.
of 2x4 /umber. TL50596
Figure 84. Scaling ladder made from 2x4 lumber.
114
Constructing Tactical TM 11-368
Open Wire Pole Lines Pars. 121-122
b. When used on 4x4 poles, the ladder is tilted, so that the bent hook at the top engages the pole and is pushed into position against the pole. Take care to see that the lower hook also engages the pole. Place the ladder against the pole with the lower end firmly against the pole.
c. When used on 4x4 H-fixtures, the ladder may be placed against either pole.
d. When used on X-frames, the ladder is placed to one side of the center of the frame. A piece of field wire or rope is used to tie the ladder upright to one of the 2x4 members.
122. MARKING POLES.
a. Reason for Marking. Rapid location of line faults by maintenance personnel will be facilitated if the distance from the zero pole is marked on selected poles at regular 34 -mile intervals and in addition at landmarks, such as roads, highways, railroads, and stream crossings. Such markings should extend from the zero pole to the end of the line, or if preferred to some, fixed location beyond which the numbering system may be repeated. A 100-mile length may be considered a suitable numbering section. However, because under certain conditions information might be disclosed to the enemy, if this method were followed, even though the marking be in code, the signal officer must specify whether or not any marking of poles is to be undertaken.
b. Code System. When permitted, the following system of coded markings on poles is suggested as suitable for use, on open wire pole lines which are more than a few miles in length, to indicate distances from zero pole in miles and tenths of miles. Any arrangement of 10 letters in which the letters do not repeat may be used for the mile designation, as indicated in the following illustrations:
0-1-2-3-4-5-6-7-8-9
SIGNALCORP AUTHORIZED ABRIDGMENT BOULEVARDS BROWN KITES CORPSIGNAL
If the code selected should be "signalcorp” and the pole location $>8.1 miles P
from the zero pole, the marking would be R or PR—I. Note that a dash (—)
T
is used in place of a decimal point, which might be too small or too indistinct to be observed.
c. Type and Location of Markings. The code designation may be placed
115
TM 11-368 Tactical Open Wire
Pars. 122-125 Pole Line Construction
on the pole in several ways, depending upon the availability of materials. Where possible, letters about 3 inches high should be placed on the pole about 5 feet from the ground in a vertical position, reading from top to bottom. The code designation should be placed on the side of the pole that is most convenient for reference. Some of the methods which may be used are as follows:
(1) Stenciling or freehand painting with Signal Corps orange or red paint.
(2) Marking on the pole with a lumber-marking crayon. These markings may need to be renewed from time to time to maintain legibility.
(3) Writing on a tag which is tied or nailed to the pole.
SECTION IV Stringing Wire
123. GENERAL. This section covers the procedures for stringing wire on open wire pole lines.
124. PRECAUTIONS AGAINST DAMAGE TO WIRE. Line wire should be handled with care because its strength is greatly impaired by kinking or. nicking. If kinks or nicks have resulted from improper handling or during shipment, they must be cut out before the wire is. placed. Coils of wire from which the wrappings have been torn or partially removed during shipment should be inspected for injuries, and any injured sections should be cut out. Suitable precautions should also be taken to protect wire from being run over by vehicles, or otherwise damaged while it is being unreeled or is stretched out along the ground.
125. DIMENSIONS AND WEIGHTS OF WIRE IN COILS. The approximate lengths, weights, and dimensions of standard coils of line wire are shown in figure 85.
Wire data
Size and type Diameter of eye Weight (lb) Wire per Approximate weight per conductor mile'
of wire (in) Max Avg Min pound (ft) (lb)
080 C-S 19 125 100 75 55.5 93.5
104 C-S 19 225 200 150 34.7 158.5
104 CU 19 190 185 180 30.5 173
TL50597
Figure 85.
116
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Pars. 126-127
126. DISTRIBUTION OF LINE WIRE. Distribution of line wire preparatory to stringing will depend upon the way in which the particular job is organized. In some cases the material distribution crew will leave coils of wire at suitable intervals along the line. At other times the wire-stringing crew carries its own wire, particularly in cases where the natives might take an interest in unattended coils of wire.
127. STRINGING WIRE FROM A MOVING VEHICLE.
a. Line wires may be strung from a vehicle moving along the lead. This method has the following advantages over other methods of placing wire in tactical open wire pole line construction:
(1) Simplicity.
(2) Elimination of damage to the wire caused by contact with obstructions on the ground.
Improvised platform
Pee/pl-/7
WjS \ \ Plate
■■■■
*..wCkMIw kR\\\\\\
- -- AW11 Amo
_ 'k ‘WW > W \ g
Trailer K-36 ■ F' ' ‘ \]L A
TL50598
Figure 86. Payout reels mounted on a trailer.
117
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 127
(3) Reduced danger to personnel stationed at the reels.
(4) Elimination of personnel required to relay signals.
(5) Reduction of complications at corners.
b. Reels RL-17- (&) are mounted upon a platform made up of 2x6 or similar lumber. The assembly is placed upon a Trailer K-36 (fig. 86), orin the body of a truck. Coils of line wire are placed on the reels. The starting ends of the wires are fastened at the beginning of the line. The vehicle then is moved down the line at walking speed, thus paying out the wires. Coils should be matched according to weight so that the wires have approximately the same length. However, short coils may be spliced out as needed to reach the end of a normal stringing section. The rope shown on the reels (fig. 86) is used as a brake to prevent the reels from overrunning and To maintain sufficient tension in the line to prevent them from sagging to the ground after they have been raised.
c. Men equipped with Wire Raising Hooks LC-65 or equivalents will follow immediately behind the wire-stringing vehicle, laying out the untransposed wires up on the crossarms in their proper positions (fig. 87). Wires may also be carried up the poles or pulled up with a hand line. If there are any sharp -changes in the grade which would cause the wires to be lifted appreciably off the crossarm when tensioned, the method of holding the wire down shown in figure 94 may be used. If the support tends to lift out of the ground, side guys should be placed.
118
Figure 88. Pulling wires out from payout reels set up on the ground.
d. When line wire is strung from a moving vehicle, the wires should be tied off at reasonable intervals, usually at points corresponding to an average coil length. The wires will be tied off to the base of the nearest pole, being pulled up hand tight to avoid excessive sag in the section just completed.
e. The ends of the wires’in the new coils are tied off at the base of the same pole and the reel-carrying vehicle proceeds down the line. If necessary, the pole will be braced temporarily with a pike pole to offset the unbalanced load.
128. STRINGING WIRES BY OTHER MEANS.
a. Where it is not feasible to string the wires from a moving vehicle, the wires may be pulled in over the crossarms, using a lead rope which was previously strung over the crossarms. This method is suggested for relatively short distances. Reels RL-17-(&) should be brought to the beginning of the section on a vehicle and the wires pulled from the reels.
b. Where it is not desired to string wires by pulling in over crossarms or by laying from reels mounted on a moving vehicle, wires may be strung along the ground by pulling from reels set on a frame. This frame is mounted on a vehicle parked at the beginning of a section, or set on the ground (fig. 88). The wires may be pulled by hand or animal power, or. by the winch rope of Truck K-43, Truck K-44-B, or truck, 2 34-ton, 6x6 cargo. Care must be taken to prevent the wires from being broken or injured by catching on obstructions. A system of signals and the personnel to relay the signal from the reel set-up to the pulling end must be provided.
129. USE OF RUNNING BOARD.
a. The running board is a device used to facilitate the placing of the line
60X878 O—44-----9
119
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 129-130
wires on the crossarm In accordance with the transposition plan. The transposition scheme designed for the tactical open wire pole line does not require phantom transpositions. Only the two wires of a pair are transposed at indicated intervals and the transpositions are easy to install.
b. When wire is strung from a moving vehicle (par. 127), the use of a running board is not required. In this case, it is more practical to raise the conductors into position on the crossarms, then to tension the wire, and finally, to transpose the wires just before tying-in. The twist should be worked ahead until a dead-end is reached, or until all of the wire in a stringing section is transposed.
c. When stringing wires by other means (par; 128), running boards may be employed if available, but their use is not required, since the transposition twists may be worked ahead at the time of tensioning kand tying-in the wire in the same manner as if the wire were strung from a moving vehicle.
d. Running Board LC-47 is a standard device designed for transposing wires which are being pulled in by means of a vehicle, by hand, or by animal power, from reels set up at the beginning of the line (or a section of the line), either on a vehicle or on the ground. The running board is attached to the pulling ends of the wires and permits transposing individual pairs of wires as well as throwing phantom transpositions.
e. If Running Board LC-47, or an improvised equivalent, is required because a different transposition scheme is used, necessitating the throwing of phantom transpositions, refer to the instructions contained in TM 11-363 in the section covering open wire placing, and in Bell System Practices, Series G, Outside Plant Construction and Maintenance, Section G31.110.
130. POSITIONING OF WIRES ON CROSSARMS.
a. The pin positions of wires to be installed will be specified in the detailed plans or instructions. In general, if all eight wires are not to be installed initially, the order of installing the wires should be such as to avoid unbalanced loads on crossarms. If a single pair is to be placed on a new crossarm, place it at pin positions 7-8. A second pair, when placed, should be located at pin positions 3-4.
b. At corners, it is important to place all wires so that each wire will pull against the pin of the insulator to which it will later be tied (fig. 89). If there are transposition insulators at a corner, place both wires of a pair to be transposed so that they will push against the pin of the transposition insulator when tensioned. In placing wires on the crossarm during the laying-up operation, take particular care to see that the wires are not crossed or otherwise put in improper arrangement. Such irregularities will require correction with consequent loss of time when the wires are sagged and tied-in.
c. In straight seaions of line, place the wires on the outside of the insulators
120
Constructing Tactical
Open Wire Pole Lines
TM 11-363
Pars. 130-133
Figure 90. Position of wires on insulators in straight sections of line.
(the side away from the pole) (fig. 90). This provides maximum separation between pairs 3-4 and 7-8, which is desirable from a transmission standpoint.
131. STRINGING WIRES OVER CROSSINGS. Take special precautions to prevent accidents while stringing wires across streets, highways, or railways. If traffic can be held up for a few minutes, proceed across the crossing as though it were the usual type span. Men should be stationed at the poles adjacent to the crossing and the wires placed over the crossarms immediately after the wirelaying vehicle has passed. After the crossing is made, sufficient tension will be maintained on the wires, by means of the reel brake, to insure adequate clearance in the crossing span. A rope should be looped over the wires in the span adjacent to the crossing span, in the direction of the laying operation. By pulling on this rope, the wire in the crossing span is kept taut. If traffic cannot be held up, use an auxiliary rope support (fig. 91). In this method, the wire is brought to the near side pole adjacent to the crossing and tied off. The wire-laying vehicle then proceeds to the far side pole, and the wires are drawn back over the crossing by hand and spliced.
132. STRINGING WIRES UNDER POWER CIRCUITS. In stringing wires under electric light, power, or trolley circuits, use all means to protect the personnel from electric shock. All the wires on such lines, including guys, must be treated as dangerous. Avoid contact between any of these and the communication wires being placed. All workmen who handle wires or metal parts which could possibly become charged with power voltages must wear rubber gloves.
121
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 132-133
The work should be planned so that the length of wire installed in the pull which includes the crossing span will be short enough to permit the officer in charge to watch over the entire operation. At the point where the lines being strung pass under the power circuits, pass a handline over the communication wires and station a man to hold both ends of the handline so that the wires will not whip up into the power circuits if sudden or irregular pulls occur in stringing. If this cannot be done, the method shown in figure 91 should be used.
SECTION V
Tensioning, Tying, and Transposing Wires
133. GENERAL PROCEDURE.
a. This section describes the procedure for completing the installation c f line wires on the pole line after they have been strung along the line. This
Figure 91- Rope support for pulling wires over crossings.
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•Constructing Tactical
Open Wire Pole Lines
TM 11-368
Pars. 133-134
Figure 92. Snubbing wires with wire-pulling blocks.
work calls for skill and accuracy, as the quality of service over the completed line depends greatly on the character of the wire work.
b. After the wires have been paid out, they are raised into position on the crossarm, pulled up to proper tension, transposed, tied to the insulators, and tested, in that order. The same sequence of operations applies to wires which have been pulled-in over the crossarms, except for the raising procedure.
134. TENSIONING WIRES.
a. Fastening Wires before Tensioning. Before tensioning a section, fasten all the wires at one end of the section either by dead-ending, as at one end of the line, by splicing through to completed construction, or by snubbing the wires temporarily to the crossarm (fig. 92). In the latter case, temporary guying should be used if the load on the crossarm is unbalanced. Depending upon conditions, it may be necessary to place a pole-to-pole guy, or a crossarm guy (fig. 93), or both. Any convenient fixed anchorage may be used for temporary guys.
b. Tensioning. At the far end of the section to be tensioned, connect the line wires to the tensioning equipment and attach this equipment to the butt of the next pole in line or to other convenient anchorage (fig. 20). Provide temporary guys for the last crossarm over which the wires pass in order to balance the pull of the wires. Bring each pair of line wires to the required tension (par. 74) and snub them at the crossarm as illustrated in figure 92. Because of the friction of the wires over the crossarms, it usually will be necessary to apply an initial tension at the pulling end slightly greater than that specified and then to ease off to the specified tension.
c. Equalizing Tension. Equalize the tension along the line by agitating the wires with a wire raising tool or pike pole < and by hand at the tensioning
123
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 134
blocks. Until experience is attained in the use of this method, check the sags at the end away from the tensioning equipment and at points beyond corners in the line. Uniformity of sag within the limits given in paragraph 78 is required
TL50605
3 open and
5dose turns
2 turns around crossarm
W/re W-I45(IO9 GS) from end of crossarm on which circuit dead ends, to next pole beyond. Tobe in place, before the line wires are pulled up. May be a temporary guy.
Place guy so it will not interfere with the placing of second crossarm.
2 turns around pole
Figure 93. Crossarm guy used in wire tensioning.
Figure 94. Method of holding wires down at up-pull.
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Constructing Tactical
Open Wire Pole Lines
TM 11-368
Pars. 134-135
Figure 95. Method of making wire dead-end at insulator.
for satisfactory transmission. When the sags in the span being measured are slightly less than specified, reduce the tension at the tensioning blocks to the amount required to provide specified sags.
d. Tensioning of Two Adjacent Sections. Tensioning of two adjacent sections may be done simultaneously at their junction point if satisfactory deadends are provided at the far ends of the sections. In this operation, the tensioning blocks are attached to corresponding wires in each section, the wires are pulled up to the specified sag, and are then spliced. The proper sag will be determined by either the target or the oscillation method.
135. DEAD-ENDING.
a. Procedure. The recommended procedure for attaching line wire to an insulator at a dead-end (fig. 95) is as follows:
(1) Wrap the line wire around the groove in the insulator, pulling the wire hand tight.
(2) Pass the free end of the line wire over and around the standing part of the wire close to the insulator, and wrap on 2 34 close turns.
(3 ) Carry the free end of the wire around the insulator groove a second time, in the direction opposite the first wrap.
(4) Pass the end of the wire over the previous serving and around the line wire adjacent to the first serving. Make; at least four close turns in the direction opposite the first serving. Cut off excess wire.
b. Twisted Sleeve Dead-Ends. An alternative method of dead-ending line wires is by using double-tube sleeves twisted as shown in figure 96, Either full-length sleeves or half sleeves are suitable for use at dead-ends of this type.
c. Dead-Ending in Opposite Directions. When two line wires are dead-ended in opposite directions on Insulator IN-128, the ends of the wire should be left long and joined with a bridging connector as shown in figure 97.
125
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 135
126
Constructing Tactical TM 11-368
Open Wire Pole Lines Pars. 136-139
136. WIRE TIES—GENERAL.
a. Kinds of Ties. Wires are tied to insulators by means of soft (annealed) wire. Two kinds of ties are recommended: the standard tie and the modified horseshoe tie (pars. 137 and 138).
b. Sizes of Tie Wires. The length, size, and kind of standard tie wires for use with each size and type of line wire are shown in figure 98.
Line wire Tie wire data Tie wire
Size Material Length Size Material
080 C-S 19" 080 CU
104 CU or C-S 21" 104 CU
109 GS 19" Figure 98. 109 GS TL50610
c. Improvised Ties. If standard tie wires are not available, tie wires may be improvised from pieces of copper or copper-steel line wire for tying copper or copper-steel conductors. If so used, avoid nicking the wire with pliers during the placing and forming operations as line wire is hard drawn and is liable to fracture. If conditions permit, these improvised tie wires should be annealed by heating in a fire. For tying galvanized steel line wire, 109 GS wire may be used. Tying with this wire will be facilitated if a tie 6 or 8 inches longer than specified in the table in subparagraph b, above, is employed. Any excess length should be cut off when the tie is completed. Galvanized steel construction wire should not be used to tie copper or copper-steel wire because of the likelihood of corrosion at the point of contact between the dissimilar metals.
137. STANDARD TIE. The standard tie (fig. 99) should be used with Insulator IN-128 and other insulators having similar diameters of wire grooves. The nominal diameters of the wire grooves are: top—2^ inches, bottom— 234 inches.
138. MODIFIED HORSESHOE TIE. The modified horseshoe tie (fig. 100) should be used with Insulator IN-15 and other insulators having approximately the same or smaller diameters of wire grooves. The nominal diameter of the wife groove of Insulator IN-15 is Iff inches. Where there is no change in the grade of the line, one end of the tie wire should be wrapped in the manner shown for use where the line has a downward pull, and the other end as for an upward pull.
139. TYING-IN UNTRANSPOSED WIRES. In straight sections of the line, tie the line wires on the sides of Insulators IN-15 away from the center through-
127
TM 11-368
Pars. 139-140
Tactical Open Wire
Pole Line Construction
bolt hole in the arm, using modified horseshoe ties. At corners, place and tie the line wires so that they will pull against, not away from, the insulators. Make all ties up under strong pressure of the fingers. Make sure that all twists resulting from transpositions previously made (par. 140) are pushed ahead before the wires are tied.
140. MAKING, TYING-IN, AND CHECKING TRANSPOSITIONS.
a. Making Transpositions. At transposition points, always cross the wires of each pair to be transposed left over right and tie them left above right in the upper and lower grooves of Insulator IN-128. Select the right-hand wire of the pair and place it in the lower groove of the insulator. Place the left-hand wire in the upper groove. Note that it takes two spans to complete a transposition, that is, to interchange the pin positions of the two wires of a pair. Thus, it is necessary to make sure that the wire from the top groove of Insulator IN-128 goes to the even (higher-numbered) pin at the next pole in line. The wire from the lower groove therefore goes to the odd (lower-numbered) pin. Figure 101 shows a perspective view of a transposition with the poles closely spaced for clarity. In straight sections of line, place the wire on the side of the insulator away from the center through-bolt hole in the arm. At comers, place the line wires so that they will pull against, not away from, the insulators. The
Turn ends of tie wire back.
Wrap tie around line wire tight/y and with a long length of Jay.
Figure 99. Standard insulator tie.
128
TM 11-368
Par. 140
Constructing Tactical
Open Wire Pole Lines
twists resulting from transposing the wires are pushed ahead as the work progresses. When the number of twists becomes bothersome, cut the line wires, take out the twists, and splice through with rolled or pressed sleeve splices.
b. Tying-in Transpositions. Ties at Insulators IN-128 are of the standard type. First tie the wire in the lower groove (right-hand wire at the preceding
Under Tie
Line wire
Line wire
Turn ends of
Turn ends of tie wire back
Tie in this manner when line has downward pull.
Over Tie
Tie wire
tie wire back
Tie in this manner when line wire has upward pul I.
Wrap tie around line wire tightly and with a tong length of lay.
TL50612
Figure 100. Modified horseshoe tie.
129
TM 11-368
Par. 140
Tactical Open Wire
Pole Line Construction
Figure 101. Perspective view of transposition.
pole). Make sure that the ends of the ties are turned back close to the wire so that they cannot come in contact with the other wire of the pair or its tie. Then tie the other wire in the upper groove in the same manner.
c. Visual Check of Transpositions. (1) When the wires are being tied in, check their positions at the transposition pole, the succeeding pole, and throughout the two spans, to make sure that the transposition has been made correctly.
(2) Transpositions can also be checked from the ground by the method shown schematically in figure 102. Referring to this figure, the first step is to stand
Figure 102. Schematic diagram, visual method of checking transposition.
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Constructing Tactical
Open Wire Pole Lines
TM 11-368
Par. 140
in position A and look up at the span of transposed wires between poles 127 and 128. If it is possible to see daylight between the transposed wires throughout the span, the first "half of the transposition is correct. The second step is to move to position B and similarly view th® transposed wires in the span between poles 128 and 129. If it is possible to see daylight between the transposed wires throughout the span, the second half of the transposition is correct. (3) If the observer can see daylight between the transposed wires throughout both adjacent spans, from any single position under the pole, no transposition has been made; that is, the wires are in the same relative positions on both sides of the transposition pole.
(4) If the wires appear to cross in both spans 127-128 and 128-129 when viewed from positions A and B, respectively, but show daylight when viewed from positions Y and X, respectively, the transposition has been made right over left.
(5) If daylight cannot be seen between the transposed wires in one or both spans, from some position near the base of the pole, there is an extra twist in the transposition.
(6) A wire raising hook, or other long pole, may be used to displace one or both of the transposed wires in case unequal sag makes it difficult to check sag by the visual method. Sag differences sufficient to interfere with visual transposition checking are likely to equal or exceed allowable limits (par. 78) and should themselves be checked.
d. Electrical Check of Transpositions. (1) When crosstalk or noise is found and the accuracy of transpositions is suspected, an electrical check may be made. Such a check is also made at the time of constructing a line to verify the correctness of transpositions at an O-pole following a short transposition section, or at the end of an inserted length of insulated pair or cable.
(2) The principle underlying the method is to obtain an electrical check of the continuity of the wire starting at pin position 1. The check verifies whether the wire at the checking point is on pin position 1 or 2 and thus whether it is in the correct position shown by the transposition diagram. A similar check is made for wires 3, 7, etc. Checks may be made either (a) at the O-pole or end of inserted insulated pair or cable, as noted above; or (b) in the case of an electrical check of the transpositions as a whole, at intervals along the line. These intervals should be spaced closely enough so that compensating errors in transposition are unlikely if the check indicates the transposition to be correct. Cutting of the line wires at the checking points is not necessary. However, the wires under test must be freed from all crosses, grounds, or connections to apparatus having a d-c path between wires or to ground.
(3) The apparatus used maybe Test Set TS-26/TSM, Test Set EE-65-(&), or any other test set which provides a battery and voltmeter. If Test Set EE-65-(&)
131
TUI 11-368
Par. 140
Tactical Open Wire
Pole Line Construction
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Par. 140
is used, it is employed to make a continuity test as described in TM 11-361.
(4) If transpositions in pair 1-2 are being checked,-wire 1 is grounded at a point (such as the start of the line) where its pin position is known to be correct. Wire 2 is left open. The tester then proceeds along the line until he has just passed the point where he wishes to check the correctness of the transposition in this pair. He connects his test set from ground to the wire on pin position 1 at this point and then from ground to the wire on pin position 2. The wire on which the greater voltmeter deflection is obtained is then shown to be the one which is grounded at the start of the test section. In some cases d-c ground potential may interfere with this check. In such cases the check can be made on a metallic circuit basis by substituting for the ground a return conductor which is another wire or shorted pair, known to be continuous, on the line under test.
(5) By comparing the actual pin position indicated with the correct pin position, as indicated by the transposition drawings, the checker finds out whether there is a transposition error between the start of the section under test and the point at which he is making a check. By repeating the test at various check
133
TM 11-368
Pars. 140-141
Tactical Open Wire
Pole Line Construction
ing points, he can determine the location of the transposition error. Similarly, by grounding the odd-numbered wire of any other pair and keeping the even-numbered wire open, a check of the transpositions on that pair can be made
141. SIDE LEAD TERMINATIONS.
Where circuits on a main lead branch off to a side lead, employ the corner construction illustrated in figure 103. Place the wires so that they will bear against the insulators, as discussed in paragraphs 139 and 140.
134
TM 11-3M
Pars. 141-145
Constructing Tactical
Open Wire Pole Lines
b. Where the circuits on the main lead branch from both directions to a side lead, use the construction shown in figure 104.
c. In the case of X-frame constructions, dead-end the branch lead on an X-frame placed adjacent to the X-frame in the main line. Make the connections from the branch to the main line with insulated wire (pars. 155 and 160) and bridging connectors as illustrated in figure 105.
142. TEST POINTS. Test points will be installed in an open wire pole line only when specified by the officer in charge of construction because they introduce sources of excessive maintenance due to loose or corroded connections and cause leakage between wires and to ground. If test points are made, they should be made as shown in figure 97. If it is more desirable to have the-test point within reach, mount Terminal Strip TM-184i on the pole at a convenient height above the ground and use insulated wire to connect the several pairs to corresponding terminals. To minimize cross induction, the insulated wire should be connected to the open wire and dropped directly down to the terminal, rather than run along the crossarm and down the pole. Test points may not be placed jit poles other than those immediately adjacent to S-poles.
143. TESTS DURING CONSTRUCTION. The continuity test is made with Telephone EE-8-(&) by talking or ringing. This test may be made every 5 or 10 miles, or as required.
144. INSTALLATION OF VIBRATION DAMPERS. Although not a part of regular construction procedure, it may be desirable to install vibration dampers of loosely spiraled insulated twisted-pair wire at alternate poles in areas where winds have been found to cause magneto-striction noise (or wire singing). An effective damper of this type is shown in figure 106. These should be installed only upon specific direction of the signal officer.
SECTION VI Splicing Wire
145. SPLICING MATERIALS AND TYPES OF SPLICES.
a. Splices in line wire are made with either-rolled or pressed sleeves. The ends of the wire to be spliced are inserted in a single-tube sleeve which is constricted with a hand-operated rolling or pressing tool. The inner surface of the sleeve is coated with an abrasive to increase its holding power. Rolled and pressed sleeve splices made with sleeves develop the full strength of the line
608878 O-— 44---10
135
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 145-146
wire. In addition, the close contact obtained between sleeve and wire provides a good seal against the entrance of moisture or gases, thus preventing corrosion and the development of high-resistance joints.
b. Sleeve Rolling Tool TL-143 (fig. 108) has three grooves and Sleeve Compressing Tool TL-217 (fig. 109) has two grooves to accommodate sleeves for the various sizes of line wire.
c. The sizes and types of sleeves and the tool grooves for rolled and pressed sleeve joints in the various line wires and in 109 GS construction wire are shown in the following table (fig. 107). The sleeves listed may be either pressed or rolled.
Wire splicing data—rolled or pressed sleeves
Sleeve
Code No. _______Tool groove
Size and type of wire SigC type IT. E. Co. type Nicopress type- Material No. of TL-143 TL-217 presses*
W-153, 080 C-S C-080C 080 H.S. 1—080—C Copper Small C 2
W-74, 104 cu C-104C 104S 1-102-C Copper Small c 2
— 104 c-s C-104Q 104 H.S. —; Copper Medium Q 4
W-145, 109 GS S-109Q 109 H.S. ——— Galv. steel Medium Q 4
*The minimum number of presses which must be made in each half of the sleeve with the sleeve-pressing tool to develop the full strength of the wire.
Figure 107. TL50619
d. For information on joining sizes of wire for which sleeves are not listed in the above table, refer to Bell System Practices, Section G31.121. The sleeves listed in the Bell System Practices, other than those given in the above table, should always be rolled.
e. Combination sleeves for joining different sizes of wire are not provided. When wires of different sizes must be joined they should be dead-ended in opposite directions and joined with bridging connectors (fig. 97). This method should also be used when joining galvanized steel wire to copper or copper-steel wire.
146. MAKING ROLLED SLEEVE SPLICES. The procedure for making a rolled sleeve splice is as follows:
a. Using abrasive cloth, clean the ends of the wires to be spliced. Care should be taken to remove any corrosion products and any burrs on the end of the wire.
b. Insert the end of one of the wires in the bore of the sleeve until it butts against the constriction at the midpoint of the sleeve.
c. To hold the sleeve on the wire, make an indentation about 34 inch from the end of the sleeve with the cutting edge of 8-inch side-cutting Pliers TL-107 (fig. no).
136
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Par. 146
137
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 146
d. Place the second wire in the other end of the sleeve and repeat the operation. Take care that the wire ends do not slip partly out of the sleeve before indenting the sleeve with the pliers.
e. Operate Sleeve Rolling Tool TL-143 until the, flat portions of the rolls
138
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Pars. 146-147
Figure 110. Indenting sleeve to hold wire before rolling.
are opposite each other (fig. 108). Hold the tool beyond the end of the sleeve and place the line wire between the flats of the rollers, with the proper size groove lined up with the sleeve. Roll the sleeve by operating the ratchet wrench, or by turning the wrench without ratcheting. In the starting position shown in figure 108, the downward stroke applies the force required to roll the sleeve. Rolling should start at one end of the sleeve and continue without interruption to the other end. The handle of the tool should be held perpendicular to the line wire in order to form a straight sleeve. If the sleeve is slightly bent after rolling, no effort should be made to straighten it. The sleeve should not be passed through the rolls more than once since this will reduce the holding power of the sleeve.
f. After the sleeve has passed through the rolls, depress the roll stop and turn the wrench slowly until the roll stop engages the gear. The roll flats are then in the proper position to permit removal of the rolling tool. After the roll stop is engaged, do not attempt to turn the handle any further since damage to the tool will result. Some tools are not equipped with roll stops, and in such cases, it is necessary to turn the ratchet wrench until the roll flats are parallel.
147. CARE OF SLEEVE ROLLING TOOL TL-143. Handle the sleeve rolling tool with reasonable care. Do not drop it on the ground, or throw it in the truck. Place it in the truck in such a position that it will hot be damaged in transit. When carrying or using the tool, always place the leather strap over the wrist. In order to prevent rusting, wipe the tool occasionally with an oily rag, especially after it has been used in damp or rainy weather. The tool should be greased about once a year with a heavy grade of graphite .grease. When
139
TM 11-368 Tactical Open Wire
Pars. 147-149 Pole Line Construction
splices made in wire, will not hold up to the breaking strength of the wire, the tool should be replaced. ,
148. MAKING PRESSED SLEEVE SPLICES. In making a pressed sleeve splice, the first three steps in the procedure are the same as those given in paragraph 146 for the rolled sleeve splice. The additional steps to be taken are as follows:
a. After the wires have been placed in the sleeve and the sleeve crimped at each end (fig. 110), place the sleeve in the proper groove of Sleeve Compressing Tool TL-217.
b. Squeeze the sleeve by closing the tool until the handle bumpers meet. Make two or four presses in each half of the sleeve, as specified in the table in figure 107. The order of making the presses should be from the center indentation outward. Be sure that the required number of presses is made in each sleeve; otherwise the proper holding power will not be developed.
149. ADJUSTMENT OF SLEEVE COMPRESSING TOOL TL-217.
a. It is important that the sleeve-pressing tool be kept clean, the joints kept well oiled, and the amount of sleeve pressure kept constant. The splices should be checked occasionally with the gauge (fig. 109 B) provided for the purpose. When using the gauge, it should be applied to the pressed portion of the sleeve (at right angles to the fins). The compressed portion of the sleeve should enter the gauge with only a small amount of clearance. If the sleeve does not enter the gauge, Sleeve Compressing Tool TL-217 needs adjustment.
b. To adjust the tool, loosen the adjustment-lbcking screw one or two turns with the wrench provided (fig. 109 C). Then turn down the adjustment screw a fraction of a turn. Be sure the tool handles are open when turning the adjustment screw. Test the adjustment by pressing a sleeve and checking it with a gauge. If the pressed portion of the sleeve enters the gauge with a small amount of clearance, the adjustment is satisfactory. If the sleeve does not enter the gauge, continue the adjustment until the sleeve gauges properly. When the
• Wire splicing data—twisted sleeves
Size and type of wire Sleeve
Type No. Size Material Length (in.)
080 C-S FT-87 080 Copper 4i/2'
104 C-S FT-88 104 Copper 43/4
104 CU FT-88 104 Copper 43/4
109 GS — 109 ♦Lead-alloy coated Steel* 43/4
TL50623
Figure 111.
140
TM 11-368
Par. 149
Constructing Tactical
Open Wire Pole Lines
Bend ends as shown to prevent wire from slipping out of sleeve.
Original positionl;: of Clamp L C-24
After twisting the sleeve, bend wires back over ends of sleeve and cut off ends of wires.
5/x half turns in whole sleeves for all wires. Three half turns in all copper half sleeves.
Figure 112, Making a twisted sleeve splite.
141
TM 11-368 Tactical Open Wire
Pars. 149-152 Pole Line Construction
correct setting has been obtained, lock the adjustment with the locking screw so that the tool will hold its adjustment.
150. MAKING TWISTED SLEEVE SPLICES.
a. An alternative method of splicing line wire is the twisted sleeve method (fig. 112). This method uses double-tube sleeves of the sizes shown in the accompanying table (fig. 111). As in the case of the rolled sleeve and pressed sleeve methods (par. 146), the ends of the wires should be cleaned with abrasive cloth before splicing. The twisting is done with Clamps LC-24 (fig. U2).
5 turns, 2'4 twists 5 turns.
Caution Be sure both wires are twisted equally.
Figure 113. Western Union joint.
b. If new coils are being spliced on at the payout reels, and tha wires are being pulled over the crossarms (par. 128), tie a piece of marline in front of the splice so that the sleeve will have less tendency to catch as the wire is pulled out.
c. When splicing wires of different sizes with twisted sleeves, locate the splice close to the supporting fixture in the span having the smaller wire.
151. MAKING TWISTED CONDUCTOR JOINTS. When neither tools nor sleeves are available, line wires may be spliced by means of the Western Union joint. This type of joint is made by twisting the ends of the two wires together, first making two and one-half twists, then five close turns on each end (fig. 113). Any excess wire at the ends is cut off.
SECTION VII
Insulated Wire in Open Wire Lines
152. FIELD OF USE.
a. Open wire lines require insulated conductors wherever the use of bare wire would result in crosses, shorts, electrical leakage, or grounds. The lead-in
142
Constructing Tactical TM 11-361
Open Wire Pole Lines Pars. 152-154
wires to terminal equipment or repeaters, sections of wire where frequent tree contacts occur, and leads past obstacles where the wires come in contact witty noninsulating surfaces, are examples of locations where insulated wire is needed. However, the electrical losses in insulated wire are usually much greater than those in bare wire, particularly at carrier frequencies. Therefore all reasonable alternatives, such as tree trimming, rerouting, and modified clearances must be explored before it is decided to use insulated wire inserts in the line. Where the use of insulated wire cannot be avoided, keep the amount of inserted insulated conductor within the limits stated for the various conditions and observe carefully the described construction precautions.
b. Where insulated wire must be. inserted in copper or copper-steel open wire circuits, use Wire W-143 or W-50 if available. For use in galvanized steel open wire circuits, Wire W-110-B is satisfactory. The insulated wires should preferably be inserted on a pair-per-wire basis (pars. 15 and 159), although short lengths may be inserted on a pair-per-pair basis (par. 16).
Figure 114. Method of installing No. 3A bridging connector
153. TREE TRIMMING. Wherever -possible, contacts of bare wire with tree limbs and branches should be eliminated by trimming. This should be done at the time the wire is installed or as soon thereafter as possible. Where tree contacts are so numerous that complete trimming would seriously delay construction, substitute insulated wire for the bare wire (par. 159). Mark the location for early attention so that the necessary measures can be taken to replace the insulated wire with bare wire as soon as possible.
154. BRIDLING AND DROP WIRING. When rubber-insulated wire must be connected to open wire, as in bridling, making drop wire connections, or inserting insulated wire to avoid tree contacts, the wires should be joined by means of bridging connectors (fig. 114, 115, or 116). The types of bridging connectors to be used in each case are as follows:
a. Connecting insulated wire to 080 C-S or 104 CU or C-S litre wire....No. 3A b. Connecting insulated wire to 109 GS line wire, and connecting.........No. 6A
109 GS steel line wire to 080 C-S line wire.
143
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 155
Insulated wire prepared for termination.
Figure 115. Alternative method oj installing No. 3A bridging connector.
155. INSTALLING BRIDGING CONNECTORS.
a. Procedure, No. 3 A Type. The procedure for installing No. 3 A bridging connectors is as follows:
(1) Clean the line wire at the bridging point with abrasive cloth. Skin and clean the end of the insulated wire.
(2) Place the connector in position on the line wire, as shown in figure 114. The line wire fits in the diagonal slot under the hexagonal head.
(3) Wrap the skinned end of the insulated wire around the threaded portion of the connector, between the two washers, and tighten the nut securely.
b. Alternative Procedure, No. 3 A Type. An alternative method of installing No. 3A bridging connectors, which affords greater proteaion to the insulated wire, is illustrated in figure 115. In this method, the procedure for preparing the end of the conductor is as follows:
(1) Skin and clean the end of the insulated conductor for approximately 434 inches.
Figure 116. Method oj installing No. 6A bridging connector.
144
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Pars. 155-156
dears end of wire existing or
to be placed in the future, on arm below.
Figure 117. Method of connecting drop wires to open wire pairs.
(2) Bend the conductor back on itself until the end overlaps the braid % inch.
(3) Grip the braid and end of the conductor with pliers in one hand. Twist the conductor with the fingers of the other hand until the twists are close, leaving a small loop at the end (fig. 115).
c. Procedure, No. 6A Type. When connecting rubber-insulated wire to galvanized wire or when connecting copper or copper-steel line wire to galvanized wire, the procedure outlined below should be followed in installing the No. 6 A connector (fig. 116):
(1) Clean bare wires at the bridging point with abrasive cloth, taking care not to damage the galvanizing. Skin and clean the end of the insulated wire. (2) Place the connector in position on the galvanized wire and fasten it securely by means of the larger hexagonal nut.
(3) Wrap the end of the insulated wire or the copper or copper-steel line wire around the threaded portion of the connector between the two washers and clamp it securely by means of the smaller nut.
156. INSTALLING CROSSTALK SUPPRESSION DEVICES AT REPEATER
POINTS. At repeater points, it may be necessary to install crosstalk suppression devices on the nonrepeatered pairs (par. 226). Coil C-114 and Coil
145
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 156-158
C-114-A, used for this purpose, are connected in one of the ways shown in figure 135. These types of coils may be mounted on the pole line if the pair being equipped does not otherwise need to be brought into the repeater station at that point. Coil C-114 and Coil C-114-A are connected to the line wire with short lengths of Wire W-37, W-110-B, or W-50 and bridging connectors. Be sure to make a good connection to the binding posts of the coil.
157. CONNECTING DROP WIRES. Drop wires are taken off open wire lines in the manner shown in figure 117. The drop wire is gripped with Clamp PF-84 in order to avoid pull on the bridging connectors. When using Clamp PF-84 on twisted wire, untwist at least 8 inches of wire and install the clamp with the two conductors held parallel; if the conductors cross within the clamp, they become shorted or broken. When clamps are not available, fasten the drop wire around the top of the pole by means of a field wire tie.
158. DROP WIRE AND CABLE RUNS ALONG THE LEAD.
a. Where insulated wire or cable is run parallel to open wires, its presence causes crosstalk in the open wire circuits. The insulated conductors should be placed at least 6 inches below the crossarm (fig. 118).
b. When drop wire or cable runs extend along an open wire lead, they should be attached to Hooks PF-81 on the poles. Wires should be held with Clamps PF-84 at dead-ends and heavy corners, and with Clips PF-83 at intermediate supports (figs. 119 and 120). Spiral-four cable is supported at intermediate points with cable hangers (fig. 121), and at dead-ends and heavy
Sp/rai-four cable.
Crossarm
Hook PF-S! (provide 3/s" lead hole) X- frame leg
Cable hanger on intermediate supports. Clamp or basket hitch on dead-ends or heavy corners.
TL50630
Figure 118. Clearance required for insulated wire or cable runs on open wire line supports.
146
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Par. 158
Clamp PFQ4
Clamp PF-84
Drive hook on face or back of pole.
Drive hook on field side of pole.
Place loop of damp around shank of hook.
Figure 120. Supporting drop wire in runs along the lead.
147
TUI 11-368 Tactical Open H ire
Pars. 158-159 Pole Line Construction
Figure 121. Intermediate support for spiral-four cable, using hanger.
corners with clamps or basket hitches of field wire. The usual vertical clearance requirements should be observed.
c. On X-frames, the same method of attachment is used. Hook PF-81 is installed in one leg of the frame and the wire or cable is attached to this hook by means of a clip, hanger, or clamp (fig. 118).
159. INSULATED CONDUCTORS INSERTED ON A PAIR-PER-WIRE BASIS.
a. General. To the extent possible, employ a single type of bare conductor throughout the entire length of an open wire line. This includes, where feasible, running regularly spaced open wire to a point as near to the terminal and repeater equipment as practicable, whether such point is a crossarm fastened to a building wall, improvised ground frame, or other usable place of attachment. However, it will sometimes be necessary for purposes of concealment, or because of unfavorable terrain or tree conditions, to insert lengths of insulated conductors in the line. Such construction introduces transmission losses and increases crosstalk. Both depend upon the method of insertion and the state of the weather.
b. Procedure, (1) The best method of inserting insulated conductors in an open wire line is on a pair-per-wire basis. In this method, both conductors of a twisted pair, such as W-143, or W-50 (W-110-B is less satisfactory but can be used where the preferred wires are not available) are used in place of a single bare line wire. They are joined to the latter with bridging connectors (fig. 122). The insulated wire is dead-ended with Clamps PF-84 or a field wire basket hitch. If possible, the insulated wires are suspended in the same manner as the hare line wire; that is, with uniform sags and insulator spacing and in a regular continuation of the established transposition pattern. Ties to insulators are standard or modified horseshoe ties made from pieces of single insulated conductor of W-110-B. This is the preferred type of construction where excessive tree contacts cannot be avoided or where temporary facilities are required during repair or conversion, or preceding special construction. Sags suitable for insulated wires used in this manner are given in figure 18.
148
Constructing Tactical
Open Wire Pole Lines
TM 11-368
Pars. 159-160
(2) In the unusual case in which regular wire spacing and separation cannot be provided in sections of insulated wire inserted on a pair-per-wire basis, short distances may be covered with wire supported by any available means and in the best configuration possible under the circumstances. For example, if the wires are to be fastened to trees, try to keep the separation between wires of a pair about 8 inches and have the pairs 16 inches or more apart. Introduce transpositions at the customary intervals. Where the wires are run on trees, each wire will be supported by a sling consisting of a short length of Wire W-110-B securely fastened to a drive hook or spike in the tree about 3 feet above the point where the line, wire will be supported. Two basket hitches (par. 51, TM 11-369) are applied to the insulated line wire, and the tail wires of these basket hitches are tied together with square knots. The lower end of the sling wire is then taken under the tied tails of the basket hitches and is tied off securely. The insulated line wire then hangs at the end of a 3-foot sling of field wire which will minimize the effects of tree sway on the line wire.
160. INSULATED CONDUCTORS INSERTED ON A PAIR-PER-PAIR BASIS.
a. General. Insulated conductors, such as W-143, W-50, or W-110-B, used on a pair-per-pair basis (one insulated conductor for each line wire) introduce relatively large transmission losses, particularly in high-frequency carrier circuits, and have other disadvantages (pars. 16 and 220). The length of such insertions should therefore be kept at a minimum, such as the short
Clamp PFB4 with
Figure 122. Cos necling insulated wires to bare wires on a pair-per-wire basis.
149
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 160
lengths required for connecting from open wire terminating points to terminal and repeater equipment. Figure 4 gives the maximum lengths of such inserted pairs that can be used without excessive losses.
b. Inserted Lengths of Spiral-Four Cable. Spiral-four cable (Cable Assembly CC-358) will not transmit satisfactorily at frequencies above 15 or 16 kc. It is therefore not suitable for insertion in open wife lines with carrier systems employing higher frequencies. Short distances, comparable to those suitable for inserted insulated-pair wire, can be covered by using both conductors of a pair in spiral-four cable as one side of the open wire line, thus using one spiral-four per open wire pair (par. 16).
Bridging connector
Brid/e wire/W-/43 or W- 50)
Brid/e ring
3/ax3's lag screw
Telephone l/ne protector 5-pair mounted with two !4‘x2"wood screws.
Place as many080C-S wires together under ground binding post as feasibiejdridge remaining wires to those attached to binding post outside of protector, using bridging connectors.
i’ in terminating spiral-four cab/e remove outer Jacket
■'I and shield from cab/e before inserting in protector
Jl box. Wrap insulated (,i conductors with single ha!f-i; Zapped layer of friction tape.
'spiral-four cable Not more than, two coi/s on one/ag screw. DonotcoH 080C-S wire with loops of excess spiral- four cab/e
dead-end guys are omitted for dearness.
While one spiro/-four cab/e and parallel ground wire is required for each open wire pair, the termination ofon/gone spiralfbur cable undone ground wire at the protector is shown for dearness.
TL50635
Fie id wire baskethitch
080 C~5
Fie id wire /ashing
Spiral-four cable.
Spiral-four cable and 080C-S wire taped together at about 5 ft. intervals
Underpass'^
Figure 123. Construction at H-fixture adjoining an underpass.
150
Constructing Tactical TM 11-368
Open Wire Pole Lines Par. 161
161. USING SPIRAL-FOUR CABLE FOR TEMPORARY CROSSINGS AT RAILROADS.
a. Rail crossings require a minimum vertical clearance of 27 feet, which requires 3 5-foot poles with single-crossarm lines and 40-foot poles with 2-crossarm lines. Wherever possible, poles of the required length should be obtained. However, a temporary underpass can be made by means of spiral-four cable. Such underpasses, described from a transmission viewpoint in paragraph 17, should be replaced as soon as poles of the required length for overhead crossings can be obtained.
b. In constructing a spiral-four underpass, the open wire is dead-ended on an H-fixture on each side of the tracks. Lightning protection is required at the dead-end fixtures on both sides of the underpass. The general features of the construction at an end support adjoining an underpass are shown in figure 123.
c. To make the underpass, a 210-foot length of spiral-four cable with 3-mh loading at the middle point is needed for each open wire pair. This insert is obtained by cutting a measured 105-foot length, including the connector, from each end of a Cable Assembly CC-358 (¥4 mile length of spiral-four cable), joining the two connectors, and making the proper connections at the two cut ends.
d. Having cut off the required lengths of spiral-four cable, prepare the cut ends.
(1) Remove about 5 inches of sheath and steel wire braid.
(2) Skin about 2 inches of rubber insulation from the end of each of the four conductors.
(3) Clean the conductors.
(4) Twist pairs of the skinned and cleaned conductors together, white to black, being sure to join corresponding wires at the two ends. Apply a single halflapped serving of friction tape so as to cover about 1 inch of rubber jacket and 2 inches of the bunched insulated conductors.
e. Lay the prepared spiral-four cables (one loaded 210-foot length per open wire pair) under the rails and between cross ties. Remove enough ballast between and beyond the rails to cover the cables and protect them from damage by hot coals from locomotives. Allow enough cable at each H-fixture to make the vertical run up the fixture. Coil any excess cable and tie it to one of the poles of the H-fixture. Do not place the connector between the track rails.
f. Lay a length of 080 C-S wire beside each cable and lash it to its associated cable with friction tape at 4- or 5-foot intervals. These wires need be only long enough to reach across the underpass and up the dead-end support to the protector (see subpar, g below) at each side of the crossing.
g. Place a second crossarm about 6 inches below the dead-end arm and mount a telephone line protector, 5-pair, at the mid-point of this arm. Take
60.8X78 <)—44-----11
151
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 161-162
the ends of the spiral-four cables up one pole of the H-fixture and support them with field wire basket hitches attached to one pole of the H-fixture, leaving enough cable beyond the basket hitch to reach the protector.
h. Use Wire W-143 or Wire W-50 to bridle from the open wire to the protector. Connect the bridling conductors to the line wire with No. 3 A bridging connectors. Run the bridle wire in bridle rings placed at 16-inch intervals on the top crossarm. Place one ring at the center point so that all bridle wires can lead straight down to the protector. Use the bridle wires on a pair-per-pair basis and keep them as short as possible.
i. Insert the prepared end of spiral-four through one hole in the base of the protector until the friction tape is well within the protector housing. Wrap the two twisted conductor ends around adjacent binding posts under the bottom washer. Insert the prepared end of a bridling pair through the adjacent hole in the mounting and wrap one wire between the washers on each of the binding posts used with the spiral-four cable. Tighten the binding post nut and cut off any excess wire.
]. Run the 080 C-S shield wires up the dead-end fixture. Fasten them to it with occasional staples or bent-over 6d nails. Terminate the shield wires on the ground post of the protector. If all shield wires cannot be inserted under the ground post screw, terminate as many as possible and connect the remaining ones to the terminated wires with No. 3A bridging connectors immediately below the ground post.
k. Follow the same procedure as described above for completing the installation on the far side of the tracks, but check the wires for polarity before connecting them with bridging connectors to the line wire to insure that an extra transposition has not been introduced. For example, see that the lead connecting to No. 1 wire on one side of the crossing is joined to No. 1 wire on the other side, and so on.
CAUTION: If the railway is electrified, particularly on a third-rail basis, there may be considerable hazards to personnel in installing and maintaining this type of construction. The work should only be assigned to experienced and capable personnel.
162. FACILITIES REQUIRED WHEN OPEN WIRE IS TERMINATED SOME DISTANCE FROM EQUIPMENT. When it is necessary to insert greater lengths of insulated conductors, on a pair-per-pair basis, than those specified in paragraphs 16 and 17, converter or hybrid equipment must be provided at or near the junction of the open wire and insulated wire. The open wire construction at the point of connection will be similar to that which would be used if the terminal or repeater equipment were located nearby.
152
CHAPTER 5 MAINTENANCE AND REMOVAL OF OPEN WIRE LINES
SECTION I
Inspections and Repairs
163. GENERAL. To maintain the grade of service for which the open wire plant is designed, it is advisable to inspect the lines periodically and correct any undesirable conditions that may exist. Because of the haste in construction and repair of lines in the combat zone, it will be desirable to make inspections in this zone more frequently than elsewhere.
164. INSPECTION INSTRUCTIONS. During the inspections, any condition needing correction should be noted. Special attention should be given to:
a. Determining whether the amount of sag in the wires, as well as the difference in sag between the wires of a pair, conforms to requirements (pars. 74 and 78).
b. Determining whether the clearances conform to requirements, especially at crossings (par. 73).
c. Noting the presence of:
(1) Loose or broken insulators.
(2) Loose or missing ties.
(3) Debris on the wires.
(4) Tree interference.
(5) Leaning or broken supports.
(6) Faulty guys.
(7) Temporary or nonstandard construction.
(8) Incorrect or missing transpositions.
153
TM 11-368 Tactical Open Wire
Pars. 165-167 Pole Line Construction
165. REPAIR PRACTICES. General practices which should be followed in making repairs to open wire lines and associated plant are:
a. Where a short section of a line has been put out of service for any reason and it is imperative that service be restored as soon as possible, the circuits may be bridged through temporarily by means of insulated wire (par. 159). This wire should preferably be suspended in the air in an orderly manner, but may be run along the ground if necessary. In the latter case, transmission impairment is likely to be very severe. These bypasses should be kept as short as possible and removed when the damage has been repaired and the circuits restored (pars. 14-17).
b. When repairs are to be made on working circuits, notify the wire chief before beginning any work that might cause service interruptions so that arrangements can be made to release the circuits. If it is not feasible to release the circuits, bridge the section with insulated wire as discussed in subparagraph a above.
c. Upon completing major repairs on circuits, notify the wire chief and obtain an O.K. test.
d. In making repairs involving the splicing-in of new wire, use wire of the same type and gauge as that in the line to avoid introducing reflection losses.
e. Leave temporary repairs in the plant no longer than is absolutely necessary.
166. CORRECTING INADEQUATE CLEARANCES. When making line repairs or changes, the clearances specified in paragraph 73 should be observed. The usual methods for correcting inadequate clearances are as follows:
a. Remove excessive sag in the wires.
b. Place pole top extension fixtures (par. 106) or place longer poles. Do not provide added clearance by decreasing the distance (3 feet) between crossarms in the case of 2-crossarm lines.
167. RESAGGING.
a. In some circumstances it may be necessary to resag wire lines, as for example:
(1) When the original sagging work has not been satisfactory and there is an excessive average difference in sag between wires of a pair or between pairs (pars. 74 and 78).
( 2 ) When adding new circuits and the existing ones are too tight or too loose. (3) When a line has been disturbed by storms, enemy action, or troop movement.
b. Before beginning the resagging work, determine whether the circuits are being used, and if so, whether they can be temporarily taken out of service. If it is necessary to resag working circuits, do not cut the wires without placing
154
Maintenance and TM 11-368
Removal of Open Wire Lines Pars. 167-172
an insulated wire bypass around the part to be cut, pending the resplicing. The bypass lengths should be securely connected to the line wire by bridging connectors (par. 155).
c. Before adjusting the sag in an existing line, check the guying to determine whether the improper sag is caused by the anchors giving at corners and dead-ends. Such conditions, when found, should be corrected before resagging or stringing new wire.
d. The resagging procedure should follow the method used for sagging new wire (pars. 75-77). The ties should be removed from the pair of wires over a convenient length, the wires properly tensioned, and then retied. Lengths of wire should be spliced in or cut out as required. In doing so, take care not to interrupt working circuits. Momentary contacts or hits between line wires interfere seriously with teletypewriter service and should therefore be guarded against in working on teletypewriter circuits.
168. REMOVAL OF DEBRIS. The following methods for removing debris from wires are suggested:
a. Throw or place a handline over the wires involved. Hold both ends of the handline and slide it along the wires to engage the foreign material. Pull the material to a point where it can be removed. Agitating the wires by means of the handline will sometimes dislodge the foreign body.
b. Tree trimmers may be found useful in dislodging or cutting the material.
169. TREE INTERFERENCE. Where tree interference with open wire exists, all contacting limbs or foliage should be pruned or removed. The contact of trees with line wires can cause serious transmission losses.
170. WIRE REPAIR. In repairing wire, if there is not sufficient slack in the wire to make a splice, introduce a short length of wire of the same type and gauge as that in the line. When doing this, it is important that the sags in the wires of a pair be uniform and that clearances be maintained (pars. 73, 74, and 78).
171. DEFECTIVE WIRE JOINTS AND CONNECTIONS.
a. Remove any defective or temporary splices and resplice with rolled or pressed sleeve joints. If it is necessary to piece the wire, observe the precautions cited in paragraph 170.
b. Replace any bridging connectors which have caused trouble.
172. LOOSE TIES. Replace broken or missing ties with new ones of the proper size and type. Replace loose ties where the line wire has pulled out of
155
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 172-177
the insulator groove. Avoid injuring the line wire when removing or replacing ties.
173. DEFECTIVE INSULATORS. Replace defective or missing insulators.-Insulators that have pulled off pins should be securely reinstalled. If the threads on the pins are stripped or worn, replace the pins.
174. INADEQUATE GUYS. Give special attention to the guying at corners and dead-ends. Where the guying is inadequate, place additional guys. Where there is evidence that the anchors are. not holding, reset existing anchors or install new ones.
175. BROKEN SUPPORTS. Replace broken or faulty supports, as they are a hazard to the linemen and a source of line trouble.
176. INCORRECT TRANSPOSITIONS. Correct any transposition errors. Such errors might be responsible for troublesome cross-induction. In checking transpositions, refer to figures 8, 9, and 10 and to paragraphs 25 and 140.
\
SECTION II
Location of Faults on Open Wire Lines
177. GENERAL. Troubles on open wire circuits are similar electrically to the troubles usually experienced on other types of circuits. A basic discussion of trouble types, together with methods of locating and clearing them, is presented in FM 24-5.
a. The existence of circuit trouble on working lines usually becomes apparent first to the switchboard operators. When this happens, the operators report the nature of the trouble and the circuit number to the wire chief. The wire chief, with the aid of maintenance personnel at various points on the line, then proceeds with initial tests to determine whether the trouble is located in operating equipment or in a particular section of the open wire line. Depending upon the nature of the trouble, the required tests may involve telephone talking tests, telephone listening tests, ringing tests, or electrical measurements.
b. When the initial tests indicate that the trouble is located in a particular line section, final location and clearance will be directed by a wire chief, a testman, or a repeaterman. In the following discussion, the person directing the work will be referred to as a tester.
156
Maintenance and
Removal of Open Wire Lines
TM 11-368
Pars. 178-179
178. LOCATION OF FAULTS.
a. When the initial tests indicate that trouble exists on a particular line section, the tester should:
(1) Determine nature of trouble.
(2 ) Make electrical tests to determine approximate location of trouble.
(3) Send linemen to the indicated trouble point. Whenever linemen are out trouble-shooting on a given circuit, both ends of the circuit should be terminated in a telephone or a switchboard drop if possible, to facilitate calling in. The linemen proceed to the vicinity to which they were directed by the tester. If the trouble is not readily located, the linemen perform one or more of the following operations:
(a) Call in to see which terminal can be reached and so determine the direction in which the trouble lies.
(b) Call the tester and cooperate in making more accurate location tests.
(c) Make measurements in the vicinity of the trouble, if equipped with portable testing apparatus such as a volt-ohmmeter.
b. In certain cases, when testing circuits, it is necessary to open the circuits. To eliminate unnecessary cutting of the line wires, test points may be inserted as discussed in paragraph 142.
179. TYPES AND CAUSES OF FAULTS. The following information will assist linemen and testers in determining what to look for when locating and clearing troubles on open wire lines.
a. Opens. (1) The open circuit, or open, is a break or cut in either one or both of the conductors of a circuit.
(2) Opens may be due to a number of causes, such as kinks, nicks, poor splices, excessive tension, heavy sleet, fallen trees, etc. Opens are often combined with crosses, shorts, or grounds.
(3) Opens cause total failure of the circuit.
b. Shorts. (1) The short circuit, or short, is caused by electrical contact between the two conductors of a circuit.
(2) Common causes of short circuits are tree contacts, broken insulators, faulty ties, excessive sag, wrapping of line wires in high winds, conducting scrap or debris thrown across the wires, etc. Short circuits may be swinging or solid, that is, intermittent or steady.
(3) Swinging shorts cause transmission to fade or to cut out. Solid shorts usually prevent use of the line.
c. Grounds. (1) The grounded circuit, or ground, occurs when there is an electrical path to earth from one or both conductors of a circuit. High resistance grounds are usually referred to as leaks.
(2) Grounds or leaks in open wire lines are usually caused by wire making
• 157
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 176-180
contact with trees, by missing or broken insulators, or by wire lying on the ground.
(3) Grounds do not usually cause complete failure of a circuit; if only one side of a circuit is grounded, the circuit will usually be noisy and may be subject to telegraph thump and crosstalk. If both sides of a circuit are grounded, the circuit may be subject to the above-mentioned difficulties; in addition, transmission will be impaired, sometimes to the point of complete failure.
d. Crosses. (1) The crossed circuit, or cross, is caused by electrical contact between the conductors of two adjacent circuits. It is really a short circuit between a conductor of one circuit and a conductor of another circuit.
(2) The causes of crosses are the same as those indicated for shorts.
(3) Crosses are usually evidenced by severe noise and crosstalk.
180. FAULT LOCATION EQUIPMENT.
a. Telephone EE-8-(&), described in TM 11-333, is used by wire chiefs, testers, and linemen as a means of communicating and also to make talking, listening, and ringing tests.
b. Test Set EE-65-(&), described in TM 11-361, is used by wire chiefs, testers, and linemen for diagnosing line trouble and for making certain trouble location tests. It consists essentially of a voltmeter, battery, telephone set, and suitable keys. It is capable of measuring voltage, loop resistance, and insulation resistance, and can also be used to some extent for locating opens. In order to measure resistance or to locate opens with this set, it must be calibrated.
c. Cabinet BE-70-(&), described in TM 11-345, is generally similar to Test Set EE-65-(&). It is intended for use by wire chiefs and testers in larger installations.
d. Test Set 1-49 is a small, compact, Wheatstone bridge containing instructions on the inner side of its cover. It is intended for use by wire chiefs and testers in measuring loop resistance and insulation resistance, as well as for locating shorts, grounds, and crosses.
e. Test Set TS-26/TSM is a small, compact, direct-reading volt-ohmmeter intended for use by linemen, and by wire chiefs or testers in connection with Test Set TS-27/TSM. Condensed instructions are included on the cover of each set. It is capable of measuring voltage, loop resistance, and insulation resistance. It can also be used for short range location of opens. Resistance values may be read directly by means of this set. Tables of loop resistance for the various types of commonly used conductors, and tables for the short range location of opens by the volt-ohmmeter test method, are included as a part of each set.
f. Test Set TS-27/TSM is a portable combination a-c/d-c bridge intended for use primarily by wire chiefs and testers. It is used for measuring loop and insulation resistance and for locating shorts grounds, crosses, and opens. Com
158
Maintenance and TM 11-368
Removal of Open Wire Lines Pars. 180-183
plete instructions contained in each set include resistance tables and open location curves for the various types of line facilities normally employed.
181. WIRE DATA. Resistance values measured in connection with fault location tests made to locate shorts, grounds, and crosses, usually must be converted into mileage values in order to determine the distance to a fault. This is done by dividing the measured resistance by the resistance per unit length of the wire being tested. The resistance values of several different types of wire commonly used in constructing open wire lines are given in figure 3, paragraph 13. These resistances are in ohms per loop mile. The resistance per conductor mile is one-half of the resistance per loop mile: The d-c loop resistance values given in figure 3 are those which apply at 70° F. Approximate values for other temperatures can be calculated by adding 2 percent to the values in the table for each 10° F increase in temperature above 70° F, or by subtracting a like amount for each 10° F below 70° F. The accuracy of fault location will be improved by using these corrections when air temperatures vary substantially from 70° F.
SECTION III
Line Removal
182. GENERAL. This section sets forth general methods and safety precautions to be followed in the removal erf open wire lines, and the procedure for sorting and disposing of the wire, crossarms, and other equipment.
183. PRECAUTIONS. In removing open wire lines, it is important that the operations be conducted in a manner which will insure safety to the personnel and a minimum of damage to reclaimable material. Some of the more important precautions which should be taken are as follows:
a. Do not climb supports unless their condition has been checked and they are known to be safe, or until sufficient temporary guying has been installed to make them safe.
b. Wear rubber gloves while cutting and removing wires, if there is any possibility of the wires coming in contact with power wires or attachments to power lines. As a further guard against electric shock, prevent supports from coming in contact with power wires, particularly if the supports are wet.
c. At railroad crossings, highway crossings, and the like, be especially careful. Accident hazards are more prevalent at such locations than elsewhere along the line.
rf. In pulling out wires crossing under power circuits, keep the wires taut
159
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 183-184
with a handline attached to the free ends; maintain a tail load so that the wires will not sag or whip excessively.
e. Do not remove guys before the wires are removed.
f. Do not cut wires in such a manner as to place a sudden or severely unbalanced load on a support or crossarm.
184. REMOVAL OF WIRE. In removing line wire from a pole line, the general procedure to be followed is set forth below:
a. Untie the line wire at the insulators.
Figure 124. Lifting poles out of ground with pole derrick.
160
Maintenance and TM 11-368
Removal of Open Wire Lines Pars. 184-186
b. In sections in which there are no heavy corners or crossing spans, cut the wires into convenient lengths of not less than 34 mile. The cut sections may then be dropped to the ground over the ends of the crossarms. At heavy corners, or in sections including crossing spans, it may be necessary to cut the wires into lengths less than 34 mile. Where special procedures may be necessary, as in the removal of wires crossing over railroads or heavily traveled highways, reference should be made to Bell System Practices, Section G31.505.
c. Pull out the wire by means of a power-driven wire-take-up reel, such as the type CR collapsible power reel of Trucks K-43 and K-44. Use a drag line to prevent the accumulation of excessive slack and to control the ends of the wire.
d. Tie each coil of recovered wire securely in at least three places before removing from power reel.
185. REMOVAL OF CROSSARMS AND OTHER EQUIPMENT.
a. Crossarms usually are not removed until after the support has been laid on the ground. If conditions make it desirable to remove crossarms while still in the air, lower them to the ground with a handline.
b. Remove crossarm braces and insulators after the arms have been lowered to the ground. Remove and pack insulators carefully so that they may be re-used. Avoid injury from cracked or chipped insulators.
186. REMOVAL OF SUPPORTS. In removing the usual types of line supports, the procedures are as follows:
a. X-Frames. Release the guys at the anchors, lay the frame on the ground, and dismantle.
b. 4x4 Supports. (1) In loose soil, remove 4x4 supports and small poles by hand, by rocking and lifting. Where the supports cannot be removed in this way, use a pole derrick to pull out the support in the manner illustrated in figure 124. The use of the pole jack will probably not be necessary with these poles.
(2) An alternative method is to pull the poles over with a winch rope, as shown in figure 125. A disadvantage of this method is that it is likely to break the pole.
c. Round Poles. (1) To remove round poles, use the pole derrick method shown in figure 124. Use pikes or handlines for guiding the pole as it is being removed.
(2) The pulling-over method shown in figure 125 may be used when no derrick is available.
161
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 187
£__
187. SORTING AND DISPOSING OF MATERIAL.
a. Sort all removed line equipment at a convenient point and reclaim all material that is suitable for re-use. Supports, crossarms, insulators, hardware, and wire may be re-used if in satisfactory condition.
a,
—Near top of pole 25 ft. or fess in length. At /east 25 ft above ground for longer poles.
/>■
fit
TL50637
Figure 125. Pulling poles over with a winch rope.
'to _ ....
' METT.
4
Not fess than length of
b. Since copper wire has a high salvage value, copper ties and pieces of copper wire should be salvaged.
c. Insulators should be sorted according to type and should be packed separately, if possible, to avoid breakage.
d. All re-usable material should be disposed of in accordance with instructions from higher authority. Material having no re-usage or salvage value should be disposed of locally in a manner which does not leave any hazardous conditions.
162
CHAPTER 6
SUPPLEMENTARY DATA
SECTION 1 Safety Practices
188. GENERAL. A soldier accidentally injured at his work is just as definitely out of the fight as a soldier injured by enemy activity. Most accidents can be prevented by careful planning and close cooperation of all personnel to insure safe working practices.
189. BASIC SOURCES OF ACCIDENTS. Large percentages of accidents occur because of improper training in safety practices and inadequate supervision of work operations. Accidents also result from the failure of workmen to observe safety practices, from improper use of tools, short cuts, undue speed, carelessness, and from defective materials and tools.
190. RESPONSIBILITY OF INDIVIDUALS FOR ACCIDENT PREVENTION. It is the duty of each crew member to plan and carry out his individual work operations in a safe manner. When an individual disregards safe practices or takes unnecessary chances, he endangers not only himself but also his fellow workers. In this connection, the following rules are important:
a. Know the job and do it the safe way.
b. Obey instructions.
c. Use the right materials, tools, and equipment and see that they are in proper condition.
d. Horseplay, wrestling, and practical jokes on the job are dangerous. Do not take part in them.
e. Always be careful and considerate of fellow crewmen.
191. GENERAL PRECAUTIONS FOR OPEN WIRE LINE CONSTRUCTION.
a. Traffic Warning. When working on highways, or in areas of heavy vehicular traffic, always station a guard to warn traffic and protect the members of the crew.
b. Weather Conditions. Working under unusual weather conditions, such as in storms, floods, or other special situations, presents more than ordinary hazards, and extra precautions should be taken to protect the crews. During
163
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 191-194
electrical storms, extreme precautions should be taken by linemen to avoid shocks when working on poles and when handling open wire and strand.
c. Power Hazards. When working in the vicinity of power lines, follow all rules relating to power line clearances. Perform telephone work in the vicinity of power lines, on the assumption that any metallic portion of the power line is alive with a dangerous voltage. Rubber gloves should be worn by personnel working in the vicinity of power lines.
192. TREE AND BRUSH CUTTING. Most of the injuries received during right-of-way clearing and tree trimming operations are caused by breaking and falling limbs. Be careful that twigs and small branches do not injure the face and eyes. Allow plenty of room to swing an ax or brush hook. Warn fellow workers when a tree is about to fall. Use a saw or tree trimmer when working aloft in trees. Never use an ax for this type of work.
193. POLE LINE WORK.
a. Before climbing any pole, be sure it is in safe condition. If a pole is not guyed, has excessive up-pull or down-pull, or appears in any way questionable, test it before climbing. This may usually be done by rocking it vigorously back and forth by use of a pike pole held at an angle of about 45°. If a questionable pole cannot be tested with the pike pole, such as one at a corner, it should be guyed with ropes or braced with pike poles before climbing. When climbing poles, make sure gaffs are put into solid wood each time. Look out for knots, checks, nails, etc., which may cause a cut-out. Do not use climbers on 4x4 poles; use the scaling ladder.
b. Do not wear linemen’s climbers while riding in a vehicle, while walking over irregular or vine-covered ground, or while assigned to ground work.
c. Be sure body belts and safety straps are in good condition. When attaching the safety strap to the dee ring, do not rely on the click of the snap hook. Look at it to make sure it is properly engaged. In passing the strap around the pole, make sure the strap is not twisted. Never place a safety strap around a pole above the top crossarm. The strap may slip off.
d. All tools and materials not normally carried in the body belt should be raised and lowered by means of a handline.
e. Be careful not to drop tools while working aloft. Tools dropped or thrown from a pole may seriously injure a crewman working on the ground in the vicinity.
194. PLACING AND REMOVING OPEN WIRE. Three particular haz-ards are encountered in open wire work:
a. Contacts with Power Wires. Consider each metallic portion of a power structure as carrying a dangerous voltage. Always maintain adequate 164
TM 11-368
Supplementary Data Pars. 194-196
clearance from all metallic parts of a power structure. Do not depend upon the insulation of potver tvires. Treat them as bare wires. A rope which may contact power structures should be dry and free from metallic strands. All measuring tapes used for wire work should be made of cloth and free from metallic strands. Be careful that loose or broken wires do not flip into power conductors.
b. Broken Poles Resulting from Unbalanced Loads. Never remove wires from a terminal pole without first placing temporary guys so that the pole will be secure after the wires are removed. In dismantling a line, be sure that the pole being worked on, and nearby poles, will stand. Place temporary guys to hold against unbalanced loads. Take every precaution to insure that nothing done while working on a pole will endanger a workman on a nearby pole. A handline may become a hazard when working aloft. When climbing, coil and loop the handline over the pliers or other tool in the body belt; when using it, tie the end of the line to the pole or crossarm, never to the body belt. Keep the free end away from moving objects.
c. Handling Strand and Wires. Protect the eyes and hands from loose or broken ends of wire or strand. When strand is being transported or when it is to be stored in coils, tape the ends to the coil.
195. WORKING FROM LADDERS.
a. General. Inspect any ladder before using it to see that it is in safe working condition. A ladder of sufficient length should always be selected for the work to be done.
b. Ladders with Rungs. These should be long enough to permit the work to be done from at least the fourth rung from the top. Place the ladder so that the bottom is set out one-quarter of a ladder length from the object against which the top rests. Lash the top to a secure support. When an extension ladder is lashed in position, the security of the position of the workman can be increased by passing one leg between adjacent ladder rungs. Always face a ladder when ascending or descending and use both hands on the ladder rails.
c. Scaling Ladders. When placing the scaling ladder, make sure it » positioned firmly against the support, with the hooks engaged. Climb the ladder with the hands encircling the pole. When working from a scaling ladder, be careful to have a safety strap passed around the support below the crossarm.
196. MOTOR VEHICLE POLE DERRICKS AND WINCHES. Pole derricks and winches can cause serious injuries if improperly used. The best safety rule for winch ropes, tow ropes, and construction tackle is to check the security of attachment before applying a load and to stay clear of ropes under tension.
a. Signals. When operating pole derricks and winches, hand signals between crew members and the motor vehicle operator should be thoroughly understood by each person who has occasion to use and interpret them.
165
TM 11-368 Tactical Open Wire
Pars. 196-199 Pole Line Construction
b. Power Hazards. Extreme precautions should be exercised when using a pole derrick in locations where it or the winch rope may come in contact with power wires.
c. Winch Ropes. Wear Gloves LC-10, or similar gloves, when handling winch rope, to prevent injury from broken strands. Never guide a winch rope by hand; use a bar for a guide. Keep hands away from the winch drum. Never straddle a winch rope.
SECTION II
Care of Tools
197. GENERAL. Too great emphasis cannot be placed on care and proper use of the tools required in building and maintaining telephone lines. Not only does the quality of workmanship depend upon the availability of sound, suitable tools, but the speed of construction and, to some extent, the safety of the workmen also depend on these same factors. Accidents to personnel often result from the use of broken or dull tools and may be as instrumental in slowing down the job as lack of proper materials or faulty planning and supervision. Proper supervision should include not only the provision of suitable tools and equipment for the job, but also the giving of definite instructions in the care and maintenance of tools and construction equipment.
198. CARE AND USE OF TOOLS AND SAFETY EQUIPMENT.. Refer to the proper technical manuals for the care and use of special tools. Detailed instructions on the inspection, repair, and use of safety equipment, such as body belts, safety straps, and linemen’s climbers, and hand tools such as bits, drills, and screwdrivers, are not included in this manual. They are fully described in the G series of Bell System Practices.
199. GENERAL RULES FOR CARE OF FREQUENTLY USED TOOLS. This section gives a few common-sense rules and precautions to be followed in caring for frequently used tools and equipment.
a. Climbing Tools. (1) BODY BELTS AND SAFETY STRAPS. Each individual is responsible. for seeing that the belt and strap issued to him are free from visible defects, such as cracks in the leather. The lineman will make sure that his equipment has no broken steel reinforcing plates, loose or broken rivets, damaged leather loops over the reinforcing plates, or broken or rotted stitching. Particular care should be taken to insure that the leather is properly cleaned, greased, and oiled. Mineral oils and greases should never be used for dressing leather. Remember that wet leather is easily damaged by heat and
166
TM 11-368
Supplementary Data Par. 199
should never be dried by being placed near steam pipes, stoves, and other heated objects.
(2) LINEMEN S CLIMBERS. All climbers should be inspected for defects before each use. Each climber should be free from broken or loose straps and the gaffs and leg irons free from fractures. The gaffs should not be loose. They must be kept sharp. Dull gaffs will not penetrate deeply enough into a pole to insure a safe grip. Sharpen gaffs with a file. Check the gaff length and shape with a gaff gauge. Never use an emery wheel for sharpening climber gaffs.
b. Cutting Tools. (1) CARE OF TOOLS. Axes, brush hooks, chisels, draw knives, and similar edged tools should be kept clean and sharp. A sharp tool is a safer and more effective tool than a dull one. Where guards for the cutting edges of such tools are supplied, they will be kept in place at all times when the tools are not in use. When guards are not provided, or are missing, the tools will be racked or stored in such a way as to protect the cutting edges, or improvised guards should be made up from friction tape or other available materials.
(2) BITS AND DRILLS. Bits and drills should be kept sharp and straight. Wood bits should be inspected to eliminate those with broken screw points, dull spurs, and bent shanks. When not in use, bits and drills will be kept in tool rolls, racks, or specially provided receptacles.
c. Striking Tools. Hammers and other striking tools will be inspected for loose or split handles, and cracked or mushroomed faces. Never use tools with loose or split handles. When the striking faces of hammers, masonry drills, and similar tools show signs of mushrooming, they should be properly dressed before re-use.
d. Screwdrivers. The tips of screwdriver blades should be kept straight and square, and all broken or chipped tips replaced. A screw slot damaged by a defective tip means time lost on the job if the screw has to be removed.
e. Ropes and Tackle Blocks. Inspect ropes, winch rope hooks, tackle and snatch blocks, slings, and chains periodically for visible defects and excessive wear. The strength of tackle blocks is governed by the hooks provided with the blocks; that is, the hook is designed to show signs of opening before any part of the block will fail because of excessive strain. Tackle hooks showing signs of overstress should not be repaired, but should be replaced by the proper new hooks. Winch rope hooks which have been badly cut should be replaced.
f. Ladders. Ladders should be inspected to insure that side rails and rungs are free from cracks, splintering, excessive wear, or decay. If, because of such defects, there is any doubt about the ladder being safe to use, exchange it for one in good condition. The hardware on extension ladders and stepladders should also be examined to determine whether fittings are broken or cracked and whether the lock springs are functioning properly. Ladder ropes and pulleys
608878 ()—44----12
167
Tactical Open Wire
Pole Line Construction
TM 11-368
Pars. 199-201
should also be kept in good working condition. Ladders found defective must be marked or tagged "Dangerous. Do not use.”; they must then be repaired or replaced at the first opportunity.
SECTION III
Storage of Crossarms and Poles
200. GENERAL.
a. This section describes the methods to be used in stacking crossarms, 2x4 and 4x4 pole lumber, and round poles in storage. Orderly storage of timbers: (1) Minimizes warping and , twisting of material during the storage period. (2) Facilitates quick inventory of stocks.
(3) Conserves storage space.
(4) Simplifies the handling and withdrawal of material.
b. In order to simplify the description of stacking procedures, in the following paragraphs it is assumed that the materials are to be stacked along a road or vehicular way.
201. STACKING CROSSARMS.
a. A plot of reasonably level ground at least 10 feet square is required for each stack of crossarms. Grade and level the ground in such plots, if necessary. Allow space for vehicular access to the stacks.
b. Make stack foundations as follows:
(1) Place two crossarms, one on top of the other, wide face down, parallel to the road, to serve as a front foundation.
(2) Similarly, place a rear foundation consisting of two arms parallel to and to the rear of the first pair. Space the front and rear foundations so that the first layer of arms will overhang about 6 inches at each end.
(3) Place a third pair of arms parallel to and midway between the other two pairs.
(4) Adjust the foundations so that they -will support the stack evenly and firmly.
c. Place a layer of crossarms on the foundations. Lay them at right angles with the foundations and with the wide face down. Allow about 34 inch separation between arms.
d. Place a second layer on top of the first and at right angles to it, allowing about 34-inch separation between arms.
e. Continue cross-piling in this manner, alternating the direction in the , layers, until the stack is about 6 feet high.
f. Cover each stack with a roof made of any available material to protect the top layers of arms from direct sunshine.
168
TM 11-368
Supplementary Data Pars. 202-203
202. STACKING POLE LUMBER.
a. The general method of stacking pole lumber is similar to that used for crossarms. Provide foundation areas at least 25 feet square, grading and levelling the plots as necessary. Stack 2x4 and 4x4 stock separately. Always pile 2x4’s with the wide face down.
b. Make foundations from the type of lumber to be piled, using two 2x4’s or one 4x4, as required, for each foundation. Lay 2x4’s wide face down, one on top of the other. Space the front and rear foundations so that the first layer of lumber will overhang the foundations about 6 inches at each end (a little over 18 feet apart for 20-foot stock). Space three intermediate foundations parallel to, and at equal intervals between, the front and rear foundations. Adjust the foundations so that they will hold the pile evenly and firmly.
c. Cross-pile the lumber in layers as described for stacking crossarms, spacing the adjacent pieces so that they will be about % inch apart in the layer. Continue cross-piling until the stack is about 6 feet high.
d. Cover each stack with a roof made of any available suitable material to protect the top layer from direct sunshine.
203. STACKING ROUND POLES.
a. Piling Round Poles in Large Storage Yards. (1) Select reasonably flat areas, grading and levelling as necessary, so that the poles will be evenly supported. Pile each size of pole separately.
(2) Place the first layer of the stack directly on the ground, alternating the direction of butts and tops of poles in the layer to the extent necessary to keep the pile even. Place enough poles in the layer to form an approximate square. (3 ) Place the second layer of poles on top of the first and at right angles to it, alternating the butts and tops, as in the first layer.
(4) Continue cross-piling in this manner, alternating the direction of the poles in the layers, until the stack is about 8 feet high.
CAUTION: The purpose of alternating the butts and tops of the poles in each layer is to keep the pile reasonably level. Chock the outside poles in each layer securely, to prevent their rolling off the pile. Provide adequate working space between piles.
b. Piling Round Poles in Small Storage Yards or Along the Line. Pile the poles directly on the ground in bunches, like matches, parallel to the road. Make a separate stack for each length of pole. Keep the piles low, not to exceed 4 feet in height.
CAUTION: Use substantial chocks to prevent the outer poles on the bottom layer from rolling. Wire together three or four of the poles on the outer edges of the first and second layers to hold the pile in place.
169
TM 11-368 Tactical Open Wire
Pars. 204-206 Pole Line Construction
SECTION IV
Supplementary Transmission Considerations
204. PURPOSE AND SCOPE. This section covers the general transmission design of long tactical open wire telephone circuits. General transmission design implies the layout of types of wires, and repeater and carrier equipment, so that satisfactory telephone circuits result if the facilities are properly installed. Information on design can be only approximate and is intended more as a guide than as a set of definite rules.
205. TYPES OF CIRCUITS.
a. General. An over-all loss of about 30 db at 1,000 cycles is as much as is considered reasonable for any telephone connection. Telephone circuits for mili-tary use may be divided into classes described as: point-to-point circuits, offshoot links, and main axis links. The classification depends upon the amount of loss allowable in the particular type of circuit.
b. Point-to-Point Circuits. These circuits connect directly from one telephone to another or from one small switchboard to another. In the latter case, the telephones connecting to the switchboards are assumed to have very short loops with losses of not more than a few tenths of a decibel, so that a 30-db loss may be taken in the circuit between the two switchboards.
c. Offshoot Links. These circuits extend from a telephone to a switchboard, or between two switchboards, through one of which they may be connected to a main axis link or another offshoot link. The pet loss of these circuits should be confined to 12 db in order that two such circuits can be used together or with a main axis link between them.
d. Main Axis Links. Main axis links are designed to provide low net loss (about 6 db) circuits which are suitable for lines between higher headquarters and for equivalent uses. Any combination of main axis links and offshoot links may be connected together as long as the over-all net loss of the switched circuits does not exceed 30 db. For example, several main axis links, two or three main axis links and an offshoot link, or a main axis link and two offshoot links may be joined together without exceeding the maximum allowable net losses for the circuit established.
206. WIRE LINE CIRCUITS AVAILABLE. The kinds of wire circuits which generally may be used are: voice-frequency circuits on insulated pairs or cables, on open wire side circuits and sometimes phantoms; 4-channel carrier circuits on spiral-four cable assemblies or Wire W-143 loaded at %-mile intervals with 170
TM 11-368
Supplementary Data Pars. 206-209
6-millihenry loading coils; and 4-channel carrier circuits on open wire pairs. The carrier system on open wires may be the open wire applique carrier system (CF-4 and CF-5) or the 2-wire carrier hybrid system (CF-7). The open wire pairs generally will be 080 C-S wires. Phantoms of these pairs will generally result in poor circuits because of the noise and crosstalk conditions. The voicefrequency circuits are generally 2-wire circuits and may be repeatered as needed. Rubber-covered pairs or cables may also be loaded either by built-in coils or by separate coils. Certain emergency facilities, such as the spiral-four carrier system used on two open wire pairs on a 4-wire basis, and ground-return circuits are covered in paragraphs 222, 223, and 225.
207. USE OF CIRCUITS. In general, since the carrier systems will provide net losses as low as 6 db, they are suitable for long main axis links. Nonre-peatered voice-frequency circuits will permit such low net losses only for short lengths, but are suitable for moderate length circuits with net losses of 12 db and 30 db, that is, for offshoot links or point-to-point circuits.
208. TELEGRAPH CIRCUITS. Any telephone circuit which has 25-db loss or less, low static noise, and is comparatively free from interruptions and clicks, is suitable for the operation of voice-frequency telegraph systems. D-c telegraph circuits may be obtained from almost any wire facilities by using a simplex circuit (except, of course, when the phantom is used on- open wire, in which case the phantom may be simplexed), or on a composited basis on open wire circuits. The limitations on such use are given in paragraph 221 and figure 132.
209. GENERAL TRANSMISSION LIMITATIONS. A satisfactory telephone circuit has the following features:
a. It has an over-all net loss in wet weather that does not exceed the value specified for the particular service under consideration, that is, 6, 12, or 30 db, and on repeatered circuits does not become so low in dry weather that over-all singing occurs, or poor quality due to near-singing exists.
b. It does not have too much noise on it. Excessive noise would prevent understanding even if the net loss were low.
c. It does not have much crosstalk. Too much crosstalk would act as interference in much the same way as noise, and would allow overhearing of speech on other circuits.
d. It has a'reasonable margin against singing (sustained oscillation) and excessive echoes. Speech would otherwise be distorted and would be hard to understand.
e. It has a transmitted frequency band of sufficient width so that speech will sound reasonably natural.
171
TM 11-368 Tactical Open Wire
Pars. 209-212 Pole Line Construction *
f. Repeaters and terminals will be arranged so as not to overload. Overloading would effectively increase the net loss, cause distortion, and cause interference with other channels on carrier circuits, particularly those carrying voicefrequency carrier telegraph channels.
210. NOISE AND CROSSTALK. For military circuits in general, 35 dbRN1 at the receiving terminal is considered a reasonable maximum value for design purposes. In forward areas where hasty construction and infrequent maintenance are sometimes necessary, 41 dbRN might be tolerable. For general use, 60-db loss from the sending end of the disturbing circuit to the receiving end of the disturbed circuit is considered a reasonable minimum crosstalk loss limit. In forward areas, a minimum loss of 43 db might be tolerable.
’This abbreviation means decibels above reference noise. This unit may be measured with a particular type of noise meter.
SECTION V
Transmission Design
211. NONREPEATERED CIRCUITS. For voice-frequency circuits without repeaters or carrier terminals, the limiting loss may be determined by multiplying the circuit length by the wet attenuation (figure 3, par. 13, or figure 126 below) and adding any bridging losses, reflection losses, or equipment losses. The losses given in these tables are only approximate, and in certain cases much higher losses may be obtained. Also, the losses in figure 3 are for 200-foot pole spacings (with specified exceptions), and will be a little greater for 150-foot spacings. This difference may be generally neglected. Also, open wire circuit losses may be much higher in wet weather if tree limbs, leaves, or other vegetation are allowed to touch the wires at a number of points. D-c telegraph circuits may be inoperative under such conditions and the telephone circuits may be very noisy.
212. VOICE FREQUENCY BRIDGING LOSSES.
a. It is sometimes desirable to add a bridged connection on a voice-frequency circuit. Figure 127 shows approximate bridging losses that may be expected for certain typical combinations. For example, a circuit from A to B may have a bridged connection added at C to provide service to an intermediate point at D which is off the main line. Adding the loss to through transmission (fig. 127) to the attenuation from A to B (computed as described in par. 211) gives the over-all loss from A to B, including the bridging loss. The loss from A to D in this example may be determined by adding the attenuation from A to C,
172
TM 11-368
Par. 212
Data on insulated pairs and cable at temperatures of approximately 70° F.
Type No. Description Weight per mile (pounds)" — Loading" 1,000-cycle impedance* Cut-off frequency (kc) Voice-frequency talking range without amplification (miles for 30 db) Approximate attenuation per mile in db*
Breaking strength (pounds)* D-c ohms per loop mile 1000 cycle capacitance ((if per mile)
1 kc 8 kc 11 kc 20 kc 30 kc
WC-548 Rubber-insulated spiral-four side circuit' 540 500 71 0.12 Nonloaded 235—j200 — 23 1.3 2.5 2.7 5 3.4
CC-358 Rubber-insulated spiral-four side circuit 540 500 77 0.12 1320-6 475—jl05 23.6 40 0.75 0.8' 0.95 1.5 —
CC-358 Rubber-insulated spiral-four twin-pair 540 500 39 0.27 Nonloaded' 130—j85 57.7 23 1.3 2.5 2.7 3.5 4.4
W-143 Rubber-insulated parallel pair 240 230 35 0.21 Nonloaded 130—j 105 — 25 1.2 2.1 2.2 2 > 2.9
240 230 50 0.21 3300-88 870—j20 3.0 100 0.3 — — — —
W-50 Rubber-insulated twisted pair — rain 320 400 26 0.23 Nonloaded 110—j80 — 30 1 1.7 1.8 2.2 2.9
damp 320 400 26 0.22 Nonloaded 115—j 80 — 30 1 1.9 2.1 3 4.2
dry 320 400 26 0.065 Nonloaded 215—jl45 — 55 0.55 0.85 0.9 1.05 1.25
rain 320 400 35 0.23 5280-88 695—jl5 2.2 100 0.3 — — — —
damp 320 400 35 0.22 5280-88 710-HO 2.3 60 0.5 — — — —
dry 320 400 35 0065 5280-88 l,2O5+)O 4.3 120 0.25 — — — —
CC-345 Rubber-insulated 5-pair cable 600 *425" 90 0.14 Nonloaded 240—j220 — 18 1.7 3.7 4 4.6 5
CC-355-A Rubber-insulated 10-pair cable 1,200 *75Ob 90 0.14 Nonloaded 240—j 2 20 — 18 1.7 3.7 4 4.6 5
W-110-B Rubber-insulated twisted pair — rain 120 300 186 0.18 Nonloaded 300—j 270 — 11 2.8 6.4 7.2 8.9 11.2
damp 120 300 186 0.15 Nonloaded 350—j280 — 11 2.7 5.9 6.4 7.8 9.3
dry 120 300 186 0.07 Nonloaded 485—j440 — 18 1.7 3.7 4 4.6 5.2
rain 120 300 195 0.18 5280-88 775—jl05 2.5 23 1.3 —1 — — —
damp 120 300 195 0.15 5280-88 835—j 70 2.9 19 1.6 — — — —
dry 120 300 195 0.07 5280-88 1,175—jl80 4.2 38 0.8 — — — —
W-130 Rubber-insulated twisted pair — wet 30 110 590 0.19 Nonloaded 505—j475 — 6 5 12.8 13.5 16.0 18.5
dry 3'0 110 590 0.07 Nonloaded 890—j 7 50 — 10 3.0 7.0 8.0 9.0 10.5
Lead-covered cable, paper-insulated, quadded (16 gauge) — — 42 0.062 Nonloaded 255—j214 — 40 0.73 1.36 1.43 1.63 1.87
Lead-covered cable, paper-insulated, quadded (19 gauge) — — 86 0.062 Nonloaded 345—]317 — 27 1.08 2.37 2.55 2.84 3.07
‘Weight per mile is the approximate weight of a 1-mile length of the product, eg., pair or cable, not including the reel. The lengths on a reel vary with the type of facility.
“The breaking strengths are nominal values for wire without splices except that values marked (* ) are specification minima.
'The type of loading is shown by a number representing the wire distance between loading coils expressed in feet followed by a number representing the inductance of the loading coil expressed in millihenrys.
“For loaded circuits, the 1,000-cycle impedance is for the midsection point in the loading section.
eThe conductors in the lead-covered cables are protected from moisture and are therefore stable in this respect. Cable WC-548, Cable Assemblies CC-358, CC-345, and CC-355-A, and Wire W-143 are relatively stable under exposure to moisture. The data applies when these types are exposed to moisture. Wires W-50, W-110-B, and W-130 are affected by moisture, and data is given for several moisture conditions. fCabIe Assembly CC-358 without connectors. Not issued; use salvaged Cable Assembly CC-358 if possible.
The data for the nonloaded twin-pair of Cable Assembly CC-358 applies when the side circuits are 1320-6 loaded.
TL50638
Fig. 126. Data on insulated pairs and cable at temperatures of approximately 70'
Figure 126.
173
TM 11-368
Pars. 212-213
Supplementary Data
Approximate bridging losses at 1,000 cycles.
Through line Bridging line Loss to through transmission (db) Loss from through line to bridge (db)
Open wire pair Open wire pair 3.5 3.5
W-110-B, nonioaded 5.0 2.5
W-110-B, 5280-88 3.0 4.0
Telephone EE-8-(&) 1.5 3.5
W-110-B, nonloaded Open wire pair 2.0 ' 4.5
W-110-B, nonloaded ' 3-5 3.5
W-110-B, 5280-88 1.5 4.5
Telephone EE-8-(&) 0.5 4.5
W-110-B, 5280-88 Open wire pair 4.0 3.5
W-110-B, nonloaded 3.0 2.5
W-110-B, 5280-88 3.5 3.5
Telephone EE-8-(&) 2.0 3.0
NOTES: W-110-B, 5280-88 denotes Wire W-110-B loaded with 88-mh coils at 5,280-foot spacing.
Wire W-110-B is assumed to be wet in all cases. The bridging losses would be somewhat different for dry wire.
The loss to through transmission assumes that Telephone EE-8-(&) is in the monitoring condition. The loss from the through line to the bridge assumes that Telephone EE-8-(&) is in the talking condition.
TL50639
Figure 127.
the loss from through line to bridge (fig. 127), and the attenuation from the bridging point C to D.
b. If the losses due to several bridged connections at widely separated points are added, the sum of the losses to through transmission will be obtained. If two or more bridged connections are located near one point in the line, the loss to through transmission will generally be less than the sum of the bridging losses. In the case of Wire W-110-B, wet line impedances are assumed, since it is then that the maximum attenuations are obtained. In the case of Telephone EE-8-(&), it is assumed that it is bridged onto the line by a wire pair having not over 2- or 3-db loss. With over 6-db loss between the bridging point and the telephone, the bridging loss values from figure 127 (losses determined by type of wire) should be used. With 3- to 6-db loss, intermediate values will be obtained.
213. VOICE-FREQUENCY REFLECTION LOSSES. At a junction between two kinds of facilities with different impedances, a reflection loss will occur.
175
TM 11-368
Pars. 213-217
Tactical Open Wire
Pole Line Construction
For most cases on voice-frequency circuits, this will be negligible. However, when wet, nonloaded Wire W-110-F or other nonloaded, rubber-insulated pairs are connected to loaded pairs or to open wire circuits, the reflection loss will be roughly 2 db for each such junction.
214. OTHER VOICE-FREQUENCY LOSSES. If repeating coils or other equipment are used on the circuit, an allowance should be made for their losses. Coil C-161 (repeating coil for deriving simplex telegraph or phantom circuits) has a loss of about 0.5 db in the side circuit.
215. TWENTY-TWO-TYPE REPEATERS.
a. On 2-wire repeatered voice-frequency circuits, the usual transmission limitation is due to singing. Rules are given in the information on repeaters to permit easy laying out of such circuits. In certain cases, somewhat lower net losses may be obtained by departing from these rules. Ordinarily, repeaters should not be used on phantom circuits because the crosstalk is likely to be excessive.
b. The following approximate method of determining the necessary number of repeaters and the allowable repeater spacing on a 2-wire circuit equipped with 22-type repeaters may be used. Determine the maximum loss of the line facilities in wet weather by multiplying the length of wire by the wet weather attenuation (fig. 3, par. 13, or fig. 126, par. 211). Subtract the desired maximum net loss. Divide this difference by the allowable gain per repeater from figure 128 below. This number (or the next larger whole number) gives the number (fl) of intermediate repeaters required, with end sections half as long as intermediate repeater sections.
Alternatively, two terminal repeaters may be used with about n-1 intermediate repeaters. The approximate allowable repeater spacing is ttye total length of the circuit divided by «. In all cases, wire in fairly good condition is assumed.
216. TWENTY-ONE-TYPE REPEATERS. When a 21-type repeater is used, the obtainable gain depends largely upon the condition of the wire on the two sides of the repeater. If the wire is in good condition on each side of the repeater, and if it is laid so that the pairs on each side will get wet and dry together as the humidity changes, substantial gains may be obtainable. In general, whatever the condition of the wire, only one or two such repeaters should be used in a circuit, and they should be carefully spaced to avoid interaction with each other and with the wire terminations.
117. NET LOSS VARIATIONS ON VOICE-FREQUENCY CIRCUITS. With unattended repeaters, it is necessary to be sure that the net loss does not
176
TM 11-36S
Pars. 217-218
Supplementary Data
Maximum allowable voice-frequency repeater gains, Telephone Repeater TP-14, 2-wire circuits.
Allowable 1-way repeater gain at 1,000 cycles (db)
Facility Loading* Terminal Intermediate
Side Circuits
Cable Assembly CC-358* 1320-6 9 18
Wire W-143 Nonloaded 7 14
Wire W-143 3300-88 5 10
WireW-110-B Nonloaded 4 8
Wire W-110-B Nonloaded 8 16b
WireW-110-B 5280-88 3 5
Open wire, copper 9 17
Open wire, copper-steel 7 13
Phantom Circuits
Cable assembly CC-358 Nonloaded 8.5 17
‘Sparing in feet and coil inductance in millihenrys.
bWith network and gain adjustments. TL50640
Figure 128.
become too low in dry weather. For Wire W-110-B, this limits the maximum length of a 2-wire circuit to about 25 miles. If men are stationed at each repeater to adjust the gain as required, substantially longer circuits mav be used.
218. USE OF CONVERTER CF-4-(&) AND REPEATER CF-5-(&) ON OPEN WIRE PAIRS (OPEN WIRE APPLIQUE CARRIER SYSTEM).
a. This system provides four carrier channels on one open wire pair and uses Converter CF-4-(&) (Carrier, 2-wire-4-wire), Telephone Terminal CF-l-(&) (Carrier), or Repeater CF-3-(&) (Carrier) at the ends of the open wire. At intermediate points, Repeater CF-5-(&) (Carrier, 2-wire) will be used. The four channels use frequencies from 200 to 10,600 cycles in one direction of transmission and 20,900 to 32,200 cycles in the other direction of transmission.
b. Rules for laying out facilities equipped with the open wire appliqu^ carrier system (Converter CF-4 and Repeater CF-5) are covered in the manuals on the equipment. Certain information is given here to permit the proper construction of lines which eventually may be equipped with these systems. Figure 129 shows the approximate maximum allowable repeater spacings for this carrier system on various kinds of open wire facilities. These lengths assume 200-foot pole spacings and do not include allowances for special conditions such as river and swamp crossings, intermediate sections under repair, etc., as covered in the following paragraphs.
177
Tactical Open Wire
Pole Line Construction
TM 11-368
Par. 218
Repeater section lengths for Converter CF-4-(&) (Carrier) and Repeater CF-5-(&) (Carrier) equipment on 4-pair or 8-pair open wire line.
Repeater (reptr) section lengths (miles) 30-db net loss on channel 4 No reptr
Description 6-db net loss circuits
No reptr 1 reptr 3 reptr
080 H.D. copper 185 155 140 280
104 H.D. copper 245 205 190 380
128 H.D. copper 285 235 215 440
165 H.D. copper 340 280 255 535
080 40% copper-steel 135 90 90 200
104 40% copper-steel 195 120 120 295
128 40% copper-steel 255 170 170 390
104 30% copper-steel 150 100 100 225
128 30% copper-steel 200 135 135 305
109 galv. steel 24 14 14 39
NOTES: Spacings assume line sections are entirely open wire. If there are entrance or intermediate cables, the line sections should be shortened enough to offset the loss in the cables, including the reflection losses at the junctions of the cable and open wire.
Repeater spacings given are for a well-constructed, 4-pair or 8-pair line, with nominal 8-inch wire spacing, Insulators IN-15 and IN-128, and 200-foot pole spacings. (When 080 copper wire is used, poles are spaced 150 feet apart.)’ The line is assumed to be free of tree contacts and power induction and to be in a locality where average static conditions and normal wet weather conditions prevail. The longer circuits may have far-end crosstalk exceeding the more conservative limit in paragraph 210, but will never reach the tolerable limit given there.
Spacings given for systems with no repeaters will require unequal levels at the output of the receiving amplifier in some cases, but the net loss can be adjusted in the individual channels. Transmitting levels are assumed 5 db higher than for systems with repeaters. Spacings given for systems with repeaters will permit normal line-up and maintenance procedures and assume transmitting levels of -{-10 db in the low group and -{-13 db in the high group.
Grcuits set up with the spacings given for 30-db net loss on channel 4 will require a special line-up and maintenance procedure, as levels will be too low to measure at the output of the receiving amplifier. In general, these circuits cannot be switched to other circuits and operation of voice-frequency telegraph may not be satisfactory. Lower net loss than 30 db will be obtained on some channels and facilities.
TL50641
Figure 129.
178
TM 11-368
Pars. 218-219
Supplementary Data
c. To allow for a moderate amount of entrance and intermediate cable, and for intermediate sections which may be under repair, it is suggested that the open wire line lengths between repeaters be restricted in general to about 80 percent of the indicated possible lengths. Also, this will be advantageous in some cases in laying out d-c telegraph circuits. On the other hand, it will also be possible occasionally to have a somewhat longer repeater section length than those indicated. In some cases, somewhat greater noise may be obtained and special maintenance procedures may be necessary.
d. The repeater -spacings determined here should also be coordinated with the 2-wire circuit repeater spacings discussed in paragraph 215, since it is generally desirable to have carrier and voice-frequency repeaters at the same points. D-c telegraph repeaters sections should also be considered (par. 221). Also, if other open wire carrier systems are used on the same line, it is generally necessary to coordinate the levels, the repeater points, and the directions of transmission in each frequency range to avoid excessive crosstalk.
219. USE OF 2-WIRE CARRIER HYBRID CF-7-(&).
a. Another means of obtaining four carrier channels on open wire by means of Telephone Terminal CF-l-(&) (Carrier) and Repeater CF-3-(&) (Carrier) is by using the 2-wire Carrier Hybrid CF-7-(&). By this means, four carrier channels may be obtained on one open wire pair by employing hybrid balance. However, not over two such carrier systems may be used on a 4-pair line and these should be placed on the outside pairs of the lead.
b. The use of this method is covered in the instructions on the hybrid set. The principal limitations on allowable repeater section length with this system are danger of singing, or near-singing, and possible near-end crosstalk. Nearsinging may result in poor quality and also may cause errors when telegraph channels are obtained by superposing Telegraph Terminal CF-2-(&) (Carrier) on one of the telephone channels. This limitation depends upon the 2-wire balances which are obtainable up to about 12 kc, and these in turn depend upon the regularity of line construction, the amount of entrance and intermediate cable, etc. Near-end crosstalk may be a serious limitation when high return losses are obtained. Such cross-talk may occur between two such carrier systems or to other repeatered or nonrepeatered systems on the line. Information on this limitation is given in the manual covering Carrier Hybrid CF-7-(&).
c. Figure 130 shows estimated allowable repeater section lengths on open wire circuits for two grades of balance, that is, 20 and 25 db, and various numbers of repeaters. Balances substantially higher than 25 db are not of great advantage because noise or crosstalk limitations will generally prevent any large increase in repeater section lengths.
179
TM 11-388
Par. 219
Tactical Open Wire
Pole Line Construction
180
TM 11-368
Par. 219
Supplementary Data
d. If the lengths of loaded or nonloaded intermediate cable given in figure 4 and paragraphs 16 and 17 are not exceeded, it should generally be possible to obtain 25-db balances on well-maintained lines, but these balances may be reduced under trouble conditions. Since frequencies up to 12 kc only are used in this system, it is possible Co use intermediate or terminal sections of Cable Assembly CC-358, but these may reduce the balances greatly and increase the crosstalk somewhat. The effect of such sections upon balances will depend upon where they are located in the repeater section, the best place being near the center of the repeater section. For general use with the repeater section lengths given for 20-db balances, three intermediate repeaters and 6-db net losses are suggested.
e. When nonloaded rubber-insulated cable is desired next to a repeater or terminal, the balancing network may be adjusted to take care of lengths up to about 1,000 feet. If two pairs are placed from the repeater or terminal to 2-wire Carrier Hybrid CF-7-(&), any length of nonloaded or 1320-6 loaded cable may be used from a balance standpoint. However, its loss will often restrict the repeater section lengths because only a limited amount of gain and equalization is available. The total line loss at 11 kc in one repeater section, including the open wire loss and the loss of any loaded or nonloaded cable at either or both ends (but excluding the two hybrid losses), generally should not exceed about 15 db. Somewhat greater losses are permissible under some circumstances.
f. Carrier Hybrid CF-7-(&) may also be used on Cable Assembly CC-358. However, the balances obtainable, even on cable in good condition, are rather low, because of the effect of the frequency cut-off due to loading. About 15-db
Estimated maximum repeater section lengths using Telephone Terminal CF-l-(&) (Carrier) and Repeater CF-3-(&) (Carrier) and the 2-wire Carrier Hybrid CF-7-(&) on rubber-covered pairs or cable
Description Repeater (reptr) section length (miles)
6-db net loss 30-db net loss
No reptr 1 reptr 3 reptr No reptr
Cable Assembly CC-358 (one pair only) 16 11 7 42
Wire W-143, nonloaded 12 10 9 23
NOTE: The above figures assume 15-db balances at 12 kc on the loaded wires and 25-db balances at 12 kc on the nonloaded wire. They also assume all repeaters lined up to approximately the same output levels. Somewhat longer lengths could be used by "tapering" the repeater sections.
Figure 131. TL50643
181
TM 11-368 Tactical Open Wire
Pars. 219-221 Pole Line Construction
balances can probably be obtained with careful maintenance. Figure 131 shows estimated repeater section lengths for this use.
220. NONLOADED INSULATED WIRE OR CABLE PAIRS.
a. When spaced twin-pairs cannot be used, estimates of the degradation due to inserted nonloaded insulated wire or cable pairs may be made as follows: For voice-frequency circuits without repeaters, or voice-frequency extensions of carrier circuits, the losses due to such inserted or added insulated wire or cable pairs may be computed as outlined in paragraphs 211 to 214. For voicefrequency circuits, with repeaters, the balances will be lowered so that less gain is generally usable in the repeaters. For approximate calculations, the rule is that the insertion in an open wire line of a short section of insulated wire near a repeater will require a reduction of the maximum allowable repeater gain in each direction; if the short section is inserted distant from any repeater, it will have little or no effect on the circuit balance.
b. On carrier circuits, in addition to the losses due to the attenuations from inserted, nonloaded insulated wire or cable pairs, there will be reflection losses which may be great for short sections, and crosstalk will be increased because of the reflected currents. With the 2-wire carrier hybrid system, the return losses will be degraded so that singing may occur. The inserted losses will vary with frequency, so that the losses of the various channels often cannot be equalized properly. Figure 4, paragraph 16, shows the maximum lengths of various kinds of nonloaded rubber or paper-insulated pairs which can reasonably be allowed in an open wire repeater section where a high-frequency carrier is used. The insertion loss of such sections will be about 0.1 db at 30 kc.
c. A good expedient at a terminal on the carrier applique system is to put Converter CF-4-(&) at the end of the open wire section and to bring the circuits into Telephone Terminal CF-l-(&) or Repeater CF-3-(&) over Cable Assembly CC-358. Since the frequencies of the carrier channels on the terminal side of Converter CF-4 are in the 0- to 12-kc range, they may be transmitted readily over spiral-four cable. If the distance from Converter CF-4-(&) to Telephone Terminal CF-l-(&) exceeds about 1 mile, a Repeater CF-3-(&) generally should be added next to Converter CF-4-(&). This will permit reasonable levels in the added line section and avoid certain maintenance difficulties discussed in the instruction manual on the open wire carrier system.
221. D-C TELEGRAPH CIRCUITS.
a. In general, it is expected that d-c telegraph circuits will be used on most open wire facilities. These may be derived by simplexing the pairs when telephone phantoms are not used, or simplexing the phantom, but most generally will be obtained by compositing. When composite sets are used, two grounded
182
TM 11-368
Par. 221
Supplementary Data
d-c telegraph circuits per open wire pair may be obtained, although one of them sometimes may be required for use as a signaling circuit when carrier systems using Converter CF-4-(&) and Repeater CF-3-(&) are on the same pair.
b. Figure 132 gives estimates of the lengths of d-c telegraph circuits on a composited basis which should be satisfactory for use with Repeaters TG-30 and 60-speed printers at each end, and for various combinations of Repeaters TG-30 and TG-31. These limits assume direct leakage conductance between any two wires of not over 0.25 micromho per mile. They also assume low ground resistance and are limited partly by the line resistance and partly by the leakage. The leakage assumed is roughly that which might be expected on
Guide jor determining operating ranges—368 operations per minute
Polarential or 2-path polar operation Wire W-110-B simplex Wire W-143 simplex 080 40% 104 copper copper-steel composited composited 104 40% copper-steel composited
Repeater TG-30 to Repeater TG-30, single-line section 50 mi 75 mi 200 mi 95 mi 135 mi
Repeater TG-30 to Repeater TG-30 with Repeater TG-31, 2-line sections Two 40-mi sections; total 80 mi Two 40-mi sections; total 80 mi Two 200-mi Two 50-mi sections; sections; total 400 mi total 100 mi Two 100-mi sections; total 200 mi
Repeater TG-30 to Telegraph Terminal CF-2-(&) (Carrier), single-line section 25 mi 40 mi a a a
Circuits operating at 404 operations per minute should be reduced in length to retain the same quality of transmission as obtainable at 368 operations per minute (about 60 words per minute). Typical mileage reductions without degradation of transmission below a bias tolerance of 15 on single-section lines between two Repeaters TG-30 with printers are:
Type of wire 368 opm 404 opm
W-110-B 50 40
W-143 75 70*
104 mil copper 200 200*
080 mil 40% copper-steel 95 95*
104 mil 40% copper-steel 135 135*
* Printer set at 50 on orientation range scale.
“Field wire lines are assumed for d-c extension facilities from carrier telegraph terminals.
Figure 132.
TL 50644
183
608878 0—44------13
TM 11-368 Tactical Open Wire
Pars. 221-223 Pole Line Construction
a well-constructed, well-maintained line on the average worst day in the United States; that is, it might be exceeded infrequently. Under very dry conditions, longer repeater seaions will be possible on the low-resistance wires. Under very humid conditions, especially if some tree contacts are involved, the lengths given in the table might not be satisfaaory. In particular, the crossfire caused by high direa leakage between any two wires may make it impossible to work telegraph circuits on both wires.
222. USE OF TELEPHONE TERMINAL CF-l-(&) AND REPEATERCF-3-(&) ON TWO OPEN WIRE PAIRS.
a. The carrier system for use on spiral-four cables normally employs a separate pair for each direaion of transmission, since the four channels are in the 0- to 12-kc range in each direction. The use of this system on open wire pairs would be a rather inefficient arrangement since it provides only four circuits on ttVo open wire pairs. However, it may be desirable in an emergency where the spiral-four equipment and open wire pairs are available.
b. Approximate limitations on the allowable lengths of repeater sections for circuits obtained in this manner are given in figure 133. These figures assume proper seleaion of pairs for the different directions of transmission; i.e., adjacent pairs carrying different systems should always be assigned to transmit in the same direaion. The limitations on the length of such seaions are variously determined by circuit noise, excessive crosstalk to other systems on the same lead, the maximum available gain, and the maximum available equalization range. The information in figure 133 is based on providing either 6-db or 30-db circuits. In some cases, it would be possible to exceed the indicated lengths by permitting higher noise during the static season, allowing poorer circuit equalization (particularly in channel 1), etc.
223. USE OF CONVERTER CF-4-(&) AND REPEATER CF-5-(&) (OPEN WIRE APPLIQUE SYSTEM) ON INSULATED WIRE AND CABLE PAIRS.
a. The open wire applique carrier system which uses Converter CF-4-(&) and Repeater CF-5-(&) transmits a total frequency band from about 0- to 32-kc for satisfactory operation. As explained in paragraph 220, there are severe restrictions on the amount of insulated wire or cable which may be inserted in open wire pairs used for carrier operation. However, by placing Converter CF-4- (&) or Repeater CF-5- (&) at each end of a wire or cable section (without any open wire within the same repeater seaion), it is possible to obtain satisfaaory operation with greater lengths. In this case, the principal reflection obtained is at the junaion of the wire or cable and the repeater or converter. If insulated wire circuits with different carrier circuits superposed on them are
184
TM 11-368
Par. 223
Information on repeater section lengths for Telephone Terminal CF-l-(&) (Carrier) and Repeater CF-3-(&) (Carrier) on 4-pair or 8~pair open wire line
________ Repeater (reptr) section lengths (miles)
Description 6-^Z> nst l°ss circuits 30-db net loss circuits on channel 4
1 system 2 systems 1 system 2 systems
-[-10-dbm transmitting output 0-dbm transmitting level O-or -\-10-dbm transmitting level -f-J 0-dbm level No reptr O-dbm level No reptr O-or -\-10-dbm level No reptr
No reptr 1 reptr 3 reptr No reptr 1 reptr 3 reptr No reptr 1 reptr 3 reptr
080 H.D. copper 104 H.D. copper 128 H.D. copper 165 H.D. copper 080 40% copper-steel 104 40% copper-steel 128 40% copper-steel 104 30% copper-steel 128 30% copper-steel 109 galv. steel 220 300 350 425 110 170 230 120 170 24 180 270 315 355 85 120 180 90 120 14 180 245 285 345 70 95 170 70 95 14 155 210 240 295 85 125 165 95 125 24 140 185 210 255 80 110 145 85 115 14 120 160 180 220 70 95 125 70 95 14 90 130 145 180 50 70 95 55 70 14 75 105 115 140 40 55 75 45 55 12 55 80 85 100 30 40 55 35 40 9 365 510 600 730 185 275 380 205 285 52 305 420 495 605 155 230 320 175 240 45 230 335 390 475 115 175 240 130 180 32
1. Repeater sections are assumed to be entirely open wire. If there are intermediate or entrance cables, the repeater section lengths should be shortened enough to offset the loss in the cables. 6
2. Spacings are given for a well-constructed 4-pair or 8-pair line, with nominal 8-inch wire spacing, Insulators IN-15 or IN-128 and 200-foot po e spacings. The line is assumed free of tree contacts and power induction and in a locality where average static conditions and normal wetweather conditions prevail. The longer circuits may have far-end crosstalk exceeding the more conservative limit’in paragraph 210 but will never reach the tolerable limit given there. H ’
3. Spacings are given for both 0-dbm and -j-lO-dbm transmitting level because early production terminals can be worked at 0-dbm and later production terminals can be worked at 0-, +5-, or 4-10-dbm transmitting levels.
4. Spacings given for systems with no repeaters will require unequal levels at the output of the receiving amplifier in some cases, but the net loss can be adjusted in the individual channels. Spacings given for systems with repeaters will permit normal line-up and maintenance procedures. 5. Circuits set up with the spacings given for 30-db net loss on channel 4 will require a special line-up and maintenance procedure since levels will be too low to measure at the output of the receiving amplifier. In general, these circuits cannot be switched to other circuits and operation of voice-frequency telegraph may not be satisfactory. Lower net losses than 30-db may be obtained on some channels and facilities.
TL50645
Figure 133
Fig. 133. Repeater section lengths—Telephone Terminal CF-l-(&) (Carrier) and Repeater CF-3-(&) (Carrier,
185
TM 11-368
Par. 223
Supplementary Data
separated by a foot or more, the crosstalk between them should not be a serious factor.
b. Figure 134 shows the repeater section lengths considered practicable for various kinds of wire and cable used in this fashion. In general, only one, or a very few such repeater sections, should be used in a circuit since the equalization provided is not perfect. In the case of Cables CC-345 and CC-355-A, the crosstalk between different pairs is likely to be very high at 30 kc. It should generally be practicable to use one open wire carrier system in such cables for the indicated lengths, but if more systems are used excessive crosstalk may usually be expected.
c. On nonloaded pairs in paper-insulated cables, it will, generally be practicable to apply Converter CF-4-(&) and Repeater CF-5-(&) for short lengths. The question of how many systems can be used in one cable depends so much upon the kind of cable, the number of pairs, and the condition of the cable that no specific rules can be given. Generally speaking, however, it should be practicable to place carrier systems on as many as 5 to 10 percent of the total number of pairs within the cable. In local Cables, it will commonly be found that the capacitance per circuit mile is considerably higher than assumed in
Use of Converter CF-4-(&) (Carrier, 2-wire-4-wire) and Repeater CF-5-(&) (Carrier, 2-wire) on nonloaded cable
Type of cable Allowable repeater section length (miles) Approximate reflection loss for each end of section at 30 kc (db)
W-143, nonloaded 9 4.0
WC-548, nonloaded, or CC-368 (one pair only) 7.5 2.5
CC-358, twin-pair 5 6.0
CC-345 or CC-355-A 5 3.5
W-110-B, nonloaded 2 3.0
19-gauge, paper-insulated, nonloaded 9 2.0
16-gauge, paper-insulated, nonloaded 15 2.5
‘Not more than one nonloaded cable repeater section is assumed to exist in any over-all open wire carrier system.
»Paper-insulated cable is assumed to have a capacitance of 0.062 (if per mile.
TL50646
Figure 134.
187
TM 11-368 Tactical Open Wire
Pars. 223- 226 Pole Line Construction
figure 134; in such cases the maximum possible circuit lengths will be considerably decreased. In the absence of other data, a decrease of 20 percent in the indicated repeater section length for high-capacitance cable is suggested as a reasonable approximation.
224. BRIDGING LOSSES. Pairs equipped with carrier facilities should not be bridged with other open wire or rubber-insulated pairs, or with Telephone EE-8-(&) because of the loss introduced over the frequency range and the irregularity which may result in excessive crosstalk or repeater singing. Such bridges may be obtained by proper use of Telephone Unit EE-105.
225. GROUND-RETURN CIRCUITS.
a. It may be found that one wire of an open wire pair, or one wire of an insulated pair is in good condition, while the other wire is broken or grounded, and that, therefore, the circuit is not usable as a metallic circuit. Under certain conditions, it is possible to use a ground-return circuit, employing a good wire as one side of the circuit and ground as the other. Such circuits are likely to have high noise, particularly in the high-static season, or when exposed to power induction. It is also easy to pick up conversations over such circuits from a considerable distance, and it is generally impracticable to use two such circuits on one open wire lead for any considerable distance because of the very high crosstalk between them. In the case of insulated pairs laid on the ground, the attenuation of the ground-return circuit is usually high, particularly in wet weather.
b. Figure 6 shows the approximate attenuation of certain ground-return circuits of this type with good grounds at the terminals. The losses of such circuits will be high if the resistance of the ground connection is high. In very wet soil, a ground rod may provide a satisfactory connection, but in dry soil it may be very difficult to obtain a low-resistance ground. The increase in attenuation due to ground resistance at one terminal is effectively the same as that which would result from inserting an equivalent series resistance in the circuit at that terminal.
226. CROSSTALK AROUND REPEATER STATIONS.
a. When carrier repeaters are placed on some of the pairs at a given point, and the other pairs pass by this point with no equipment on them, there are crosstalk paths from the repeater outputs to repeater inputs by way of these other pairs. This has a tendency (when high repeater gain is used) to produce repeater singing at frequencies above the operating-frequency range and crosstalk between systems in the operating-frequency range. These effects may also occur if the nonrepeatered pairs pass the repeater point at a switchboard without
188
TM 11-368
Par. 226
Supplementary Data
employing repeating coils; or if pairs with repeaters or repeating coils have the simplex legs bypassed directly around the repeaters or coils; or if wires other than the open wire conductors are placed on the pole line and these conductors pass by the repeater point without coils. Such effects may also occur even if all of the pairs are equipped with repeaters, if the repeater-station ground resistance is high. This is because the longitudinal loss of the repeaters may be very small with high ground resistance.
b. This type of crosstalk above the operating-frequency range is controlled in Repeater CF-5-(&) by a roof filter provided in the repeater. Such crosstalk within the operating-frequency range may be controlled by one or more of the following measures: insertion of suppression devices in the other pairs and in the simplex legs; reduction of ground resistance at repeater stations; and limitation of repeater section lengths.
c. The following measures should suffice to control this type of crosstalk between different carrier systems transmitting up to about 30 kc. They are not needed when only one applique carrier system is installed or when only voicefrequency or carrier systems transmitting up to about 12 kc are installed.
(1) Simplexes which are carried through the repeater station should be suppressed by telegraph apparatus, or as shown in figure 135B.
(2) Place suppression devices as shown in figure 135A in all open wire pairs which pass by the carrier repeater point without any equipment. Any such devices will degrade balances somewhat on repeatered 2-wire circuits.
(3) pairs are equipped with Repeater EE-89-(&), place a suppression device as shown in figure 135 in the pair connecting to the east side of the repeater, and the same type of device in the pair connecting to the west side of the repeater.
(4) Suppression devices as shown in figure 135A may be needed in any wires other than the open wire conductors which are placed on the line near these conductors and bypass the repeater point.
(5 ) The suppression devices shown in figure 135 should not be used in carrier pairs, since they impair carrier transmission. For proper control of crosstalk which returns longitudinally through the carrier repeaters, the repeater-station ground resistance should be kept to a reasonably low value, if repeater section lengths as long as those given in figure 129 are used. This requires a station ground resistance of not more than about 300 ohms in the case of copper-steel line wires, or 100 ohms In the case of copper line wires. Ground resistance is apt to be high in rocky or sandy locations. It can be reduced by driving additional ground rods or longer ground rods, separated from each other by a distance at least equal to their length, and by keeping the earth around the
189
TM 11-368
Par. 226
Tactical Open Wire
Pole Line Construction
SUPPRESSION DEVICES TO REDUCE CROSSTALK AROUND CARRIER REPEATER STATION
Coil C-H4 or C-H4A
TO pair West
To pair East
A-For use in any noncarrier pair
Coil C-H4 or C-ti4A
To simplex west
LI
LI
To simplex East
B-For use in simplex
NOTES-'
i. Keep West leads separated from East leads. TL50647
2. Check transmission on pair or simplex.
a A permits use of nonrepeatered phantoms, use same arrangement on both side circuits of a phantom group
a. When using A. check for noise on pair; tf phantom is used, check for phantom-to-side crosstalk and for noise on phantom If coils cause too much crosstalk or noise on circuits on which they are installed, try other samples until proper combination Is found.
Figure 135. Crosstalk suppression devices for installation at repeaters.
ground rods or grounding system moistened with a salt solution. Ground resistance can be measured approximately by the following process: Divide the ground rods into two approximately equal groups; or if only one ground rod has been driven, drive another at least 10 feet from it. With the two rods, or groups of rods, isolated from each other and from other conductors except the earth, measure with an ohmmeter the resistance between the two rods or groups of rods. Connect the two rods or groups of rods together and to the
190
TM 11-368
Supplementary Data Pars. 226-227
station ground bar. The station ground resistance is then approximately one-fourth the measured distance.
d. If a given pin position is occupied by different carrier systems on both sides of a repeater point and bypassing effects occur, crosstalk is apt to be somewhat greater than that described above. It is generally wise, therefore, to connect the input and output of a given repeater to the same pin position on the line.
e. If at an intermediate point in an open wire line there is an A terminal on one applique carrier system and a B terminal on another, the procedure given in subparagraph c above should be followed.
f. If at a carrier repeater point a nonrepeatered bypassing pair has carrier on it, the repeater gain on other carrier pairs at this point must be very low to avoid excessive direct crosstalk between repeatered and nonrepeatered pairs. Therefore, no further precautions to avoid crosstalk due to bypassing are needed in any wires at such a point.
SECTION VI
Material Requirements for Tactical Open Wire Pole Lines
227. GENERAL.
a. This section provides lists of material requirements for the construction of tactical open wire pole lines, and is intended to be used as a guide in the requisitioning and stocking of such materials. Quantities are shown for 25 and 100 miles of the various types of line described in this manual for light, medium, and heavy storm-loading conditions. The quantities shown are calculated on an average pole spacing and guying basis, usually with about 5 percent allowance of spare materials. This amount of spare assumes that the materials will be distributed carefully and used prudently. If circumstances are such that the hazards of breakage or loss are increased, or if crews will be widely separated in an area where travel is difficult, additional spare material should be allowed.
b. Although these lists will serve as a reasonable guide for establishing the usual relationships between quantities of the various materials needed under average conditions, the final estimate of materials for a given line should take into account the particular construction features for the route. For example, it may be found in surveying the route, that an abnormal amount of corner guying is required, or that numerous highway or rail crossings must be made Suitable allowances of extra or special materials must be made accordingly.
TM 11-368
Pars. 228-234
Tactical Open Wire
Pole Line Construction
228. POLES. The extra length poles shown in the various lists are for use at crossings or other points where the line must be graded. Regular length poles may be substituted where circumstances permit. One or two poles per mile are allowed for use as anchors. The poorest poles should be selected for this use.
229. LINE WIRE. The amount of line wire shown is only slightly more than actual requirements, since it is assumed that there will be very little wastage of this item.
230. CROSSARMS. The spare allowance of crossarms in the 25- and 100-mile columns is about 10 percent to provide for the occasional use of a crossarm for a pole top extension or for an earth anchor. Twisted, warped, or checked arms should be selected for the latter use.
231. GUYS. Guying for three corners per mile is assumed. In medium and heavy loading areas additional quantities of guying materials are shown to provide for such storm guys as may be necessary.
232. INSULATORS. Since insulators are more subject to breakage than other line materials, 10 percent spare allowance is shown in the columns for 25 and 100 miles of line.
233. INSULATED WIRE. The requirements for insulated wire will vary to a considerable extent. Such wire is required for individual drops (insulated lead-offs from the open wire to stations), terminating, bridging, and insertion. One hundred feet per mile is assumed, but this should be considered only as a nominal figure.
234. MISCELLANEOUS MATERIALS.
a. The 105-foot lengths of Cable Assembly CC-358 shown are for use at temporary railroad underpasses where tall poles are not available (par. 17). They are not required except where loaded insulated wire inserts are necessary.
b. The various hardware items are shown with 5 percent allowance for spare. All hardware is galvanized.
c. The quantities of bridging connectors and bridle rings are sufficient to provide for a nominal use of these materials where insulated wire is bridged to open wire. A specific estimate of the necessary quantity of these materials should be made in any particular case.
192
TM 11-368
Par. 235
Supplementary Data
193
TRI 11-368 Tactical Open Wire
Par. 235 Pole Line Construction
194
TM 11-368
Par. 235
Supplementary Data
TM 11-368
Par. 235
Tactical Open Wire
Pole Line Construction
e> R
Lt C
o
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c
Qi
o
C/5 e
u
<3
c
OC «
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bj J-}
bO
0
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bO .a
bT l» £ £ £ £ £
U)
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X -C7
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196
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•Crossarms are cut in half except at H-fixtures and X-frames.
TM 11-368
Par. 235
Supplementary Data
197
TM 11-368
Par. 235
Tactical Open Wire
Pole Line Construction
5
235. MATERIAL LISTS (cont'd).
c. (Continued)
198
TM 11-368
Par. 235
Supplementary Data
235. MATERIAL LISTS (cont'd).
d. Following is a list of materials required for tactical open wire pole line with round poles, one crossarm, eight wires, 150-foot spans in extra-heavy loading areas. This list is to be used as a guide only; requirements for the particular situation must be determined. For transportation of the material, 176.5 ship tons (40 cu ft or 2,000 lb, whichever is the larger) are required for 25 miles of line and 70o ship tons are required for 100 miles of line. These are estimated shipping weights.
£ s
kJ «
B08878 0—44-----14
§OOOOi^v>en
feb
5
6L1440 Nail, common wire, 40d.
6L9112-12 Screw, wood, steel, No. 12.
NOTE: At least one 18-foot ladder should be available for working on 22-foot and 25-foot poles.
202
TM 11-368
INDEX
Paragraph Page
Accident prevention, individual responsibility for.............. 190 163
Accidents, basic causes of....................................... 189 163
Additional wires on crossarms or poles........................... 27 z 22
Adjustment of Sleeve Compressing Tool TL-217..................... 149 140 •
Advance planning of construction, general procedure............ 30 23
Allowable changes in grade..................................... 85e 66
Allowable sag differences...................................... 78 54
Alternate routes, planning..................................... 32& 24
Anchor:
Guys ..................................................... 80c 58
Holes, digging ...................................... .... 103 86
Rod AH-4.................................................. 115c 107
Anchors:
Attaching guys to......................................... 115 101
Patent ................................................... 115c 107
Placing .................................................. 115 101
Rock...................................................... 118 111
Types of ...............................—................. 115a 101
Arms, side extension .......................................... 106d 90
Assembling X-frames ........................................... 106c 90
Attaching crossarms to poles and X-frames ..................... 106 89
Attaching guys:
To 4x4 poles.............................................. 107 92
To round poles ........................................... 109 95
To X-frames and H-fixtures .......................... . .. 108 94
Attenuations, open wire circuits................................. 13 9
Auger LC-34 .................................................... 103a 86
Avoiding highways, etc..................................... 33, 41c 25,29
Bits, care of.................................................... 199£ 167
Blocks, tackle, care of.......................................... 199^ 167
Body belts, care of.............................................. 199a 166
Bolts:
Carriage, % by 4^ used in assembling X-frames.............. 106c 90
Machine, Vz by 6, used to attach crossarms to 4x4 poles.... 106a 89
Machine, % by 10, used to attach crossarms to round poles 106b 90
Machine, % by 6, used to attach crossarms to X-frames.... 106c 90
203
TM 11-368
INDEX (Continued)
Paragraph
Brace:
Ground .................................................. 81c
PF-4, crossarm................................ 100, 105c, 1066
Push................................................ 80g, 81c
Branching lines .............................................. 26
Bridge, Wheatstone ..................................... 18CW & /
Bridging connectors:
Installing ......i....................................... 155
Table of............................................... 154
Bridging losses:
Pairs equipped with carrier facilities.................... 224 “
Voice-frequency ....................................... 212
Bridling and drop wiring..................................... 154
Cabinet BE-70-(&) ................;......................... 180c
Cable: .
CC-345 and 355-A, used with open wire applique system equipment .............................................. 2236
Entrance and intermediate, allowing for...„............ 218c
Intermediate, in open wire lines......................... 14
Loaded .................................................. 17
Loaded or nonloaded, inserted........................... 219c
Nonloaded ..............................,................ '16
Paper-insulated, use of open wire appliqud system equipment on................................................ 223c
Runs along the lead.................................... 15 8
Spiral-four, inserted in open wire lines................ 1606
Spiral-four, on open wire pole lines................... 1586
Cable Assembly CC-358, inserted in open wire lines...... 166, 1606
Cable Assembly CC-368, used for nonloaded inserts in open wire lines .............................................. 166, 1606
Cant Hook LC-32 ......................................... 110c
Carrier:
Circuits ................................................ 206
Hybrid CF-7-(&), 2-wire, use of.......................... 219
Open wire applique system used on insulated wire or cable pairs ............................................ 223
Repeaters, crosstalk around.............................. 226
Terminals and repeaters.................................. 218
62 -
83,89,90
59,62
22
158
144
143
188
172
143
158
187
179
9
13
181
12
187
146
150
146
12,150
12,150
97
170
179
184
188
177
204
TM 11-3M
INDEX (Continued)
Paragraph
Catenary long span construction............................. 116
Change in grade: Allowable ........................................................... 85e
Locating poles at....................................... 59
Measuring ........................................... 86, 87
Checking transpositions..................................... 140
Circuits:
Ground-return.................................-...... 18, 225
Lengths, long line facilities........................... 10
Connectors, bridging:
Installing .............................................. 155
Table of................................................. 154
Page 110
66
38
66
128
14,188
8
172
8,182
171
8
170
171
170
96
142
92,96
107,111
146
154
112
45
45
40
166
146
176
145
30
24,28
144
143
205
TM 11-368
INDEX (Continued)
Paragraph Page
Converter CF-4-(&) ......................218, 220c, 221, 223 177,182,184
Corners:
Guying and bracing at................................... 81 59
Pole construction at.................................... 113 99
Positioning of wires on crossarms at..........,....... 130& 120
Correcting inadequate clearances ............................ 166 154
Crew, placing, assembling, and equipping, materials and tools for ........................................................ 104 88
Crews and teams, organization.................................. 96 70
Crossarm (s):
Attaching to pole and X-frame.............„........... 106 89
Brace PF-4 ........................................... 100 83
Equipping ............................................ 105 88
Guy .................................................. 114zZ 100
Improvised............................................ 99^ 82
Materials requirements ................................. 230 192
PF-92-A, description .................................. 99 80
Removal............................................... 185 161
Stacking ............................................. 201 168
Stay ................................................. 100 83
Crosses, definition of..................................... 179zZ 158
Crossings: Highway and railroad....................................... 120 112
Normal spans, laying out.............................. 584 37
Railroad, made with spiral-four cable................. 161 151
Stringing wires over.................................. 131 121
Crosstalk:
And noise, general requirements....................... 210 172
Around repeater stations .......................... 28, 226 22,188
Suppression devices .................................. 226c 189
Suppression devices, installing at repeater points.... 156 145
Cutting tools, care of..................................... 199£ 167
Dampers, vibration ........................................ 144 135
Dead-ending wire .......................................... 135 125
Dead-ends:
Facing H-fixtures at.................................. 112^ 99
Guying at ...................................... 108Z>, 114r 94,100
Deadman (Pole Support LC-16) .............................. 110c 97
206
TM 11-368
INDEX (Continued)
Paragraph Page
Debris, removal from line................ .................. 168 155
Defective wire joints and connections, repair at............ 171 155
Depth of setting, poles..................................... 103* 86
Derrick, pole-setting, use of............................... 110
At heavy corners.................................... 113
Framing ................................................ 98g
Poles for............................................. 97c
Hammers, care of............................................ 119c
Hangers, cable, used with spiral-four cable................ 158Z>
Head guy.................................................... 80Z>
Heavy storm loading, definition of............................ 6c
Height, definition of in guying.............................. 79b
Highway crossings........................................... 1204
Highways, avoiding in selecting line routes............... 334, 4ic
P4gC
92
95
94
100
58
156
192
58
58
58
100
62
58,62,112
95
95
107
43
58
106
110
100
98
99
99
80
77
112
146
58
5
57
112
25,29
209
TM 11-368
INDEX (Continued)
Paragraph Page
Holes, pole and anchor, digging.............................. 103 86
Hook LC-32 (cant) .......................................... 110c , 97
Hooks PF-81, used to support drop wire and cable............ 1586 146
Horizontal clearances........................................ 736 46
Hybrid Carrier CF-7-(&), use of.............................. 219 179
Inspection:
Instructions ............................................... 164
Open wire pole lines, general............................... 163
Installing bridging connectors................................... 155
Insulated conductors:
Inserted on a pair-per-pair basis................. 16, 160, 220
Inserted on a pair-per-wire basis....................... 15, 159
Spaced ................................................ 15, 1596
Insulated wire:
Field of use in open wire lines........................
Materials requirements ................................
Twin-pairs ............................................
Insulated wire or cable pairs:
Entrance and intermediate .............................
153
153
144
12,149,182
9,148
9,148
142
192
9
9
152
233
15
14
Loaded................................................ 17, 160 13,149
Nonloaded............................................. 16, 220 12,182
Insulator Pin PF-59 ..................................... 1016, 1054 84,88
Insulators:
Defective, replacement of..................... ......... 173 156
IN-15, description ..................................... 1014 84
IN-128, description .................................... 10 la 84
Materials requirements.................................. 232 192
Placing................................................. 1056 88
Types and quantities for transposition poles............ 102c 86
Interpolating sags for intermediate span lengths ............ 74 49
Intersecting lines........................................... 26 22
Joining wires:
Galvanized and copper or copper-steel 145e, 155c 136,145
Of different sizes 145c 136
Joint, Western Union, for splicing wire .... 115c, 151 110,142
210
TM i 1-368
INDEX (Continued)
Paragraph Page
Ladders: Care of........................................................ 199/ 167
Safety practices in working from........................... 195 165
Scaling, how to make and use............................... 121 113
Lag screw, % by 3 V2, used with Brace PF-4 ..................... 106 89
Lead, definition of, in guying.................................. 796 57
Leaks, electrical, definition.................................. 179c 157
Lengths of circuits, various long wire line facilities......... IOcZ 8
Light storm loading, definition ...............,................. 6* 5
Line construction: Crews and teams.................................................. 90 70
General procedure ......................................... 96 76
Sequence of work operations ................................ 89 69
Speed of.................................................... 91 71
Vehicular equipment ......................... -....-........ 90 70
Line design requirements.......................-.................. 4 2
Line layout: Crew........................................................ - 486 31
Locating poles at changes in grade......... ............. 59 38
Long spans............................................... 586 38
Procedure with two or more crews..................... 60 38
Repeater locations ...................................... 58c 38
Special problems ........................................ 58 37
Timing with reference to construction...................... 49 31
Tools and equipment required by crew...................... 62 40
Line removal:
General ................................................... 182 159
Precautions................................................ 183 159
Line route map symbols .......................................... 66 41
Line supports: Symbols .....................-............—..................... 67 42
Types of................................................... 97 76
Line trend, definition and significance........................... 8 7
Line wire:
Distribution of............................................ 126 117
Precautions against damage to.............................. 124 116
Resagging ............................................... 167 155
Loaded insulated wire or cable pairs...................... 17, 160 13,149
Loading, storm, definition............................-........... 6 3
211
TM 11-368
INDEX (Continued) Paragraph Page
Location of electrical faults................................... 178 157
Long spans: General ........ ............................................... 72 45
Guyin«..................................................... 116 110
Laying out ................................... ........ 58£ 38
Losses:
Bridging: Carrier facilities ..................................... 224 188
Voice-frequency......................... 212 172
Due to coils, allowing for...................... 214 176
Reflection, voice-frequency .......................... 213 175
Main axis links.............................................. 2O5(/ 170
Marking: Pole locations................................................ 54 35
Pole location stakes ...................................... % 35
Poles .................................................... 122 115
Materials: Distributing along the line.............................. 102 84
Miscellaneous, requirements for.......................... 234 192
Preliminary estimate .................................... 35 26
Removed line, sorting and disposing of................. 187 162
Requirements for open wire pole line: Crossarms................................................. 230 192
Guys................................................. 231 192
Insulated wire .................................... 233 192
Insulators .......................................... 232 192
Line wire ........................................... 229 192
Miscellaneous........................................ 234 192
Poles.............................................. 228 192
Splicing ................................................. 145 135
Measuring: Change in grade............................................ 86, 87 66
Span lengths............................................. 55 35
Medium storm loading, definition............................... 6b 5
Modified horseshoe tie......................................... 138 127
Nails, 6d, used to fasten insulator pins..................... 105^ 88
Net loss variations on voice-frequency circuits.............. 217 176
Noise and crosstalk, general................................. 210 172
212
TM 11-368
INDEX (Continued)
Paragraph Page
Nonloaded insulated wire or cable pairs................... 16, 220 12,182
Nonloaded rubber-insulated cable, next to a repeater or terminal 219c 181
Nonloaded spiral-four cable inserted in open wire lines...... 1606 150
Nonrepeatered circuits....................................... 211 172
Notes to be made by pilot........................................ 57 36
Numbering:
Of pin positions ........................................... 20 16
Of poles, fractional........................................ 52 33
Offshoot links.................................................. 205c 170
Open wire: Factors affecting the decision to use........................ 31 23
Pole lines, field of use................................ 7 5
Opens, definition ........................................... 179<* 157
Order of equipping a second crossarm with wires.............. 24 19
Organization of construction crews and teams................. 90 70
Oscillation method of measuring sag ......................... 75 51
Osmoplastic B preservative................................... 97/ 77
Pair-per-pair insertion of insulated conductors.............. 160 149
Pair-per-wire insertion of insulated conductors.............. 159 148
Pike pole method of setting poles............................ 110c 97
Pilot:
And line layout crew.................................... 48 31
Member of survey crew .................................. 37c 27
Notes to be made by..................................... 57 36
Pin PF-59 (insulator pin) ..................................... 1016 84
Pin positions, numbering........................................ 20 16
Pins, insulator, placing....................................... 1054 88
Planning: Access to line................................................ 34 25
Advance, general procedure.................................. 30 23
Avoiding highways, etc..................................... 33 25
Completion after survey .................................. 46 30
Deciding to use open wire................................... 31 23
Selecting pole line structures.............................. 32 24
Point-to-point circuits........................................ 2056 170
Pole:
Line structure, selection of............................... 32 24
Location stakes, marking ................................... 56 35
213
TM 11-368
INDEX (Continued)
Paragraph Page
Pole (Continued) Locations, marking............................................. 54 35
Locations, selecting ..................................... 53 34
Lumber, stacking ...................................... 202 169
Pole derrick:
Safety practices ........................................ 196 165
Use of.........._................................... 110^ 97
Pole holes.................................................... 103 86
Pole Support LC-16 (deadman) ............................... 110c 97
Pole top extension fixtures:
Description ........................................... 106c 90
Storm guying at poles having........................... 119 112
Poles:
Corner, setting.......................................... 113 99
Distributing ............................................ 1026 85
Fabrication from 2x4’s................................... 986 77
4x4, setting............................................. 110* 96
Framing ................................................ 98 77
Marking ................................................. 122 115
Materials requirements ................................. 228 192
Preservative treatment.............................. 97/, 98^ 77,79
Ranging, used in measuring change in grade................ 86 66
Removal ............................................... 186 161
Round:
Description .................................... 97c, 97/ 76,77
Setting .......................................... 1106 97
Stacking ............................................ 203 169
Sawed, description ...................................... 97* 76
Setting by pike pole method............................. 110c 97
Pole-to-pole guy.....,........................................ 80c 58
Pole-to-stub guy............................................ 80^ 58
Positioning of wires on crossarms............................. 130 120
Power:
Circuits:
Removal of lines under............................. 183^ 159
Stringing wires under.............................. 132 121
Hazards, safety precautions...................... 191c, 194<# 164
Lines, avoiding .................................... 336, 41c 25, 29
Power reel, type CR, used in removing wire................... 184c 161
214
TM 11-368
INDEX (Continued)
Paragraph Page
Precautions:
Against damage to line wire............................... 124 116
For safety in open wire line construction................. 191 163
In guying............................................... 84 63
In removing open wire lines............................... 183 159
Preliminary route sketch....................................... 36 26
Pressed sleeve splices......................:................. 148 140
Protectors, telephone line, used at railroad underpass...... 161 151
Pull, definition of, in guying................................ 79c 58
Pull Finder LC-45 .............................................. 79c 58
Pullers, strand .............................................. 115c- 107
Push braces.............................................. 80g, 81c 59,62
Railroads:
Crossings made with spiral-four cable................ 17, 161 13,151
Crossings, overhead .................................... 120# 113
Electrified, precautions in working near................ 161k 152
Raising wires............................................... 127c 118
Rake, definition of......................................... 113 99
Ranging poles, used in measuring change in grade............... 86 66
Reel, power, collapsible, type CR, used in wire removal..184c 161
Reels RL-17-(&) used in stringing wire.................. 127#, 1284 118,119
Reference pole (zero pole) .....:............................. 504 32
References to other texts....................................... 3 2
Refleaion losses, voice-frequency............................ 213 175
Removal:
Crossarms................................................. 185 161
Debris from line ......................................... 168 155
Line supports............................................. 186 161
Lines, general.......................................... 182 159
Lines, precautions ....................................... 183 159
Sorting and disposing of material......................... 187 162
Wire ..................................................... 184 160
Repair:
Correcting transposition errors........................... 176 156
Defective insulators.................................... 173 156
Defective wire joints and conneaions...................... 171 155
Guys, inadequate.......................................... 174 156
608878 U—44----15 215
TM 11-368
INDEX (Continued)
Repair (Continued) Paragraph Page
Line wire................................................ 170 155
Practices, general .................................... 165 154
Supports, broken ........................................ 175 156
Ties, loose ............................................. 172 155
Repeater:
CF-3-(&) .................... 10c, 218*, 219*, 220c, 221, 222 8,177,179,
182,184
CF-5-(&) ................................. 106, 218, 223, 2266 8,177,184,
Locations, laying out.................................... 58c
Stations, suppressing crosstalk around......... 28, 156, 226
TG-30 and TG-31 ....................................... 2216
Twenty-one type ....................................... 216
Twenty-two type ....................................... 215
Resagging line wire........................................ 167
Resistance values, wire.................................... 181
Right-of-way:
Clearing ................................................. 61
Obtaining ................................................ 45
River crossings, normal spans, laying out.................... 58*
Rock anchors .............................................. 118
Rods, anchor, AH-4........................................... H5c
Rolled sleeve splices ..............v........................ 146
Rope support used in wire stringing.......................... 131
Ropes, care of............................................ 199^
Round poles:
Attaching guys to...............;........................ 109
Description ......................................... 97c, 97/
Route:
189
38
22,145,188
183
176
176
155
159
40
30
37
111
107
136
121
167
95
76,77
Marking during survey................................. 39
Of access to the line................................... 34
Sketch, preliminary................................. 36, 44
Survey, general procedure...........,................... 37
28
25
26,30
26
Rubber gloves, use of............................. 132,1836,191c; 121,159,164
Rubber-insulated cable, nonloaded, next to a repeater or terminal ................................................. 219c 181
Running Board LC-47 ...................................... 129 119
Safety practices: General ............................................... 188, 191 163
216
TM 11-368
INDEX (Continued)
Paragraph
Safety practices (Continued) Individual responsibility ................................. 190
Motor vehicle pole derricks and winches................ 196
Placing and removing line wire........................... 194
Pole line work...................... .................. 193
Tree and brush cutting................................... 192
Working from ladders..................................... 195
Safety straps, care of....................................... 199a
Sag: Differences, allowable ..................................... 78
Gauge................................. ,................. 774
Illustrated ............................................ 72
Measuring: Oscillation method............................... ..... 75
Sighting method ................................... 77
Tension method..................................... 76
Requirements ........................................... 74
Sawed poles ................................................. 974
Scale LC-64, used in tension method of measuring sag......... 76
Scaling ladder, how to make and use........................... 121
Scope of manual.............................................. 2
Screw, lag, % by 3%, used with Brace PF-4.............. 106a, 106b
Screwdrivers, care of........................................ 199