[Federal Register Volume 69, Number 136 (Friday, July 16, 2004)]
[Proposed Rules]
[Pages 42812-42840]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-15841]



[[Page 42811]]

-----------------------------------------------------------------------

Part II





Department of Labor





-----------------------------------------------------------------------



Mine Safety and Health Administration



-----------------------------------------------------------------------



30 CFR Parts 18 and 75



High-Voltage Continuous Mining Machines; Proposed Rule

  Federal Register / Vol. 69, No. 136 / Friday, July 16, 2004 / 
Proposed Rules  

[[Page 42812]]


-----------------------------------------------------------------------

DEPARTMENT OF LABOR

Mine Safety and Health Administration

30 CFR Parts 18 and 75

RIN 1219-AB34


High-Voltage Continuous Mining Machines

AGENCY: Mine Safety and Health Administration (MSHA), Labor.

ACTION: Proposed rule.

-----------------------------------------------------------------------

SUMMARY: The Mine Safety and Health Administration (MSHA/We) are 
proposing design requirements for approval of high-voltage continuous 
mining machines operating in face areas of underground mines. We are 
also proposing to establish new mandatory electrical safety standards 
for the installation, use, and maintenance of high-voltage continuous 
mining machines used in underground coal mines. These provisions would 
enable mines to utilize high-voltage continuous mining machines with 
enhanced safety protection from fire, explosion, and shock hazards. In 
addition to providing a mining environment as safe as when using low- 
and medium-voltage equipment and facilitating the use of advanced 
equipment designs, the proposed rules would eliminate the need for 
Petitions for Modification (PFMs) to use high-voltage continuous mining 
machines. Once promulgated, this rule will supercede existing 
provisions in granted PFMs.

DATES: Comments on the proposed rule must be received by September 14, 
2004. Submit written comments on the information collection 
requirements by September 14, 2004.
    Public hearing dates and locations are listed in the Public 
Hearings section below under SUPPLEMENTARY INFORMATION. If individuals 
or organizations wish to make an oral presentation for the record, we 
ask that you submit your request at least 5 days prior to the hearing 
dates. Post-hearing comments and other appropriate data for the record 
must be received by October 14, 2004.

ADDRESSES: You may submit comments, identified by RIN 1219-AB34, by any 
of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov.
     E-mail: [email protected]. Include ``RIN 1219-AB34'' in 
the subject line of the message.
     Fax: 202-693-9441.
     Mail, Hand Delivery or Courier: MSHA, 1100 Wilson Blvd., 
Room 2350, Arlington, Virginia 22209-3939.
    Instructions: All comments, including any personal information 
contained therein, will be posted without change to http://www.msha.gov/currentcomments.htm.
    Docket: The entire rulemaking record may be viewed in MSHA's public 
reading room at 1100 Wilson Boulevard, Room 2349, Arlington, Virginia.

FOR FURTHER INFORMATION CONTACT: For information concerning the 
technical content of the rule, contact Elio L. Checca, General 
Engineer, Office of Technical Support, MSHA, 1100 Wilson Blvd, Room 
2332, Arlington, Virginia 22209-3939. Mr. Checca can be reached at 
[email protected] or 202-693-9471 (facsimile). For information 
concerning the rulemaking process, contact Marvin W. Nichols, Jr., 
Director, Office of Standards, Regulations, and Variances, MSHA, 1100 
Wilson Boulevard, Room 2350, Arlington, Virginia 22209-3939. Mr. 
Nichols can be reached at [email protected], 202-693-9440 
(telephone), or 202-693-9441 (facsimile).
    You may obtain copies of the proposed rule and the Preliminary 
Regulatory Economic Analysis (PREA) in alternative formats by calling 
202-693-9440. The alternative formats available are either a large 
print version of these documents or electronic files that can be sent 
to you either on a computer disk or as an attachment to an e-mail. The 
documents also are available on the Internet at http://www.msha.gov/REGSINFO.HTM. We intend to place the public comments on these documents 
on our Web site shortly after we receive them.

SUPPLEMENTARY INFORMATION: 

I. Public Hearings

    We will hold four public hearings on the proposed rule. The public 
hearings will be begin at 9 a.m., and will be held on the following 
dates and at the locations indicated.

----------------------------------------------------------------------------------------------------------------
                     Date                                         Location                           Phone
----------------------------------------------------------------------------------------------------------------
September 21, 2004...........................  Sheraton Birmingham 2101 Richard Arlington         (205) 324-5000
                                                Jr., Blvd. North, Birmingham, AL 35203.
September 23, 2004...........................  Sheraton Suites Lexington, 2601 Richmond Rd.,      (859) 268-0060
                                                Lexington, KY 40509.
September 28, 2004...........................  Little America Hotel, 500 S. Main Street, Salt     (801) 363-6781
                                                Lake City, UT 84101.
September 30, 2004...........................  Hyatt Regency Pittsburgh Intl. Airport, 1111       (724) 899-1234
                                                Airport Blvd., Pittsburgh, PA 15231.
----------------------------------------------------------------------------------------------------------------

    If individuals or organizations wish to make an oral presentation 
for the record, we ask that you submit your request at least 5 days 
prior to the hearing dates. However, you do not have to make a written 
request to speak. Any unallotted time will be made available for 
persons making same-day requests.
    The hearings will begin with an opening statement from MSHA, 
followed by an opportunity for members of the public to make oral 
presentations to a panel. Speakers will speak in the order that they 
sign in. At the discretion of the presiding official, the time 
allocated to speakers for their presentation may be limited. Speakers 
and other attendees may also present information to the MSHA panel for 
inclusion in the rulemaking record.
    The hearings will be conducted in an informal manner. The hearing 
panel may ask questions of speakers. Although formal rules of evidence 
or cross examination will not apply, the presiding official may 
exercise discretion to ensure the orderly progress of the hearing and 
may exclude irrelevant or unduly repetitious material and questions.
    A verbatim transcript of the proceedings will be included in the 
rulemaking record. Copies of this transcript will be available to the 
public, and can be viewed at http://www.msha.gov.
    MSHA will accept post-hearing written comments and other 
appropriate data for the record from any interested party, including 
those not presenting oral statements, up to 14 days after the last 
public hearing which is scheduled for September 30, 2004.

II. Information Collection Requirements

    Comments concerning the information collection requirements must be 
clearly identified as such and sent to both the Office of Management 
and Budget (OMB) and MSHA as follows:
    (1) To OMB: All comments may be sent by mail addressed to: Office 
of Information and Regulatory Affairs, Office of Management and Budget, 
New Executive Office Building, 725 17th Street, NW, Washington, DC 
20503, Attn: Desk Officer for MSHA; and
    (2) To MSHA: Comments must be clearly identified by RIN Number

[[Page 42813]]

[1219-AB34] as comments on the information collection requirements and 
transmitted by e-mail to [email protected], by internet to 
www.Regulations.gov, by facsimile to (202) 693-9441, or by regular mail 
or hand delivery to MSHA, Office of Standards, Regulations, and 
Variances, 1100 Wilson Blvd., Room 2350, Arlington, Virginia 22209-
3939.

III. Background

A. Events Leading to Regulatory Action

    The energy used by electrical equipment in mines has increased over 
the years. Voltage to operate this equipment has also increased to 
accommodate the increased energy demand. Additionally, high-voltage 
electric equipment design has become safer than in the past, more 
efficient, and practical. Because of the industry's need for higher 
voltages and the marked improvement in the design and manufacturing 
technology of high-voltage components, we promulgated the ``Electric 
Motor-Driven Mine Equipment and Accessories and High-Voltage Longwall 
Equipment Standards for Underground Coal Mines,'' 67 FR 10972 (March 
11, 2002) (high-voltage longwall rule). These regulations and standards 
added a number of approval and safety requirements to Title 30 CFR 
parts 18 and 75 to accommodate advances in technology for high-voltage 
longwall equipment.
    Since we promulgated the high-voltage longwall rule, the mining 
industry has been moving toward the use of high-voltage continuous 
mining machines to increase productivity. High-voltage continuous 
mining machines increase productivity with a minimal increase in 
machine size. Higher voltages also require less current, resulting in 
the use of smaller cables. Smaller cables are easier to handle, and can 
reduce injuries to miners.
    Existing safety standard 30 CFR 75.1002, Installation of electric 
equipment and conductors; permissibility, does not allow mines to 
utilize high-voltage continuous mining machines in or inby the last 
open crosscut, within 150 feet of pillar workings, or on longwall 
faces. To allow mines to utilize high-voltage mining machines in the 
face area of a mine, we grant PFMs. The PFM process allows a mine 
operator to request modification of a safety standard at a particular 
mine pursuant to section 101(c) of the Federal Mine Safety and Health 
Act of 1977 (Mine Act). PFMs may be granted when a mine operator has an 
alternative method that provides the same measure of safety protection 
as the existing standard; or when the existing standard would result in 
diminished safety protection to miners. The PFM process results in 
safety requirements and procedures that are applicable only to an 
individual mine. Once a final written decision pertaining to a PFM has 
been issued, the governing terms and conditions contained in the 
decision become mandatory for the mine described in the petition. 
Following issuance of a final decision, we continue to monitor 
compliance with its terms and conditions.
    PFMs granted to date for the use of high-voltage continuous mining 
machines contain requirements for proper installation, electrical and 
mechanical protection, cable handling, and disconnecting of circuits 
and equipment. We granted the first PFM for the use of continuous 
mining machines incorporating onboard high-voltage switching components 
in 1997. From 1997 through October 2003, we granted 38 PFMs for the use 
of high-voltage continuous mining machines, and others are being 
processed.

B. PFM Requirements in the Proposed Rule

    In developing this proposed rule we reviewed the granted PFMs for 
Sec.  75.1002 to allow the use of high-voltage continuous mining 
machines. Although the proposed rule includes most requirements that 
were in the granted PFMs allowing the use of high-voltage continuous 
mining machines, it does not include all of the requirements. The table 
below indicates which requirements in the granted petitions are also in 
the proposed rule.

   Table 1.--Comparison of Requirements in Granted Petitions for Modification (PFMs) With Requirements in the
                                                  Proposed Rule
----------------------------------------------------------------------------------------------------------------
                                             Number of PFMs including
           Requirement in PFMs              requirement out of 38 PFMs    Requirement included in Proposed Rule
----------------------------------------------------------------------------------------------------------------
2,400 Volt limit for continuous mining     38..........................  No.
 machine.
120 Volt maximum control voltage.........  38..........................  Yes.
Ground-fault protection..................  38..........................  Yes.
Short-circuit protection.................  38..........................  Yes.
Look ahead circuit.......................  38..........................  Yes.
Undervoltage protection..................  38..........................  Yes.
Installation of trailing cables..........  38..........................  Yes--expanded to allow unused entry.
Trailing cable temporary storage.........  15..........................  Yes.
Guarding.................................  38..........................  Yes.
Guarding locations.......................  38..........................  Yes.
Suspended cables or cable crossovers.....  18 prohibit the use of        Yes.
                                            crossovers; 19 permit
                                            crossovers; 1 does not
                                            address the use of
                                            crossovers.
Cable design.............................  38..........................  Yes.
Maximum number of splices................  37..........................  No.
Prohibiting tape-type splices............  38..........................  No.
Qualified person to splice...............  38..........................  Yes.
Trailing cable inspection................  38 for daily inspection; 13   Yes.
                                            for inspection each shift.
Main disconnect device in power center...  38..........................  Yes.
Trailing cable disconnecting devices.....  38..........................  Yes.
Caution labels on HV compartments........  38..........................  Yes.
Grounding stick for capacitor storage      38..........................  Yes.
 devices.
Design, installation, and maintenance of   38..........................  Yes.
 disconnecting switches.
Main disconnecting devices and control     38..........................  Yes.
 circuit interlocking.
Cover interlocks.........................  38..........................  Yes--two required.

[[Page 42814]]

 
Emergency stop switch....................  33..........................  Yes.
Barrier and covers.......................  38..........................  Yes.
Troubleshooting and testing limitations..  38..........................  Yes.
Qualified person.........................  38..........................  Yes.
Ungrounded power circuits................  38..........................  Yes.
Ground-wire monitor test.................  38..........................  Yes.
Power center lockout and tag procedures..  38..........................  Yes.
Trailing cable lockout and tag procedures  38..........................  Yes.
Lockout and tagging responsibilities.....  38..........................  Yes.
Ground-fault test........................  38..........................  Yes.
Grounded-phase detector test.............  37..........................  Yes.
Remove from service if a grounded-phase    38..........................  Yes.
 occurs.
Handling trailing cables.................  38..........................  Yes.
Personal protective equipment made         34..........................  Yes.
 available by mine operator.
Visual examination of HV insulating        38..........................  Yes.
 gloves.
Air testing of gloves....................  38..........................  Yes.
Voltage testing of gloves................  38..........................  Yes.
Power sources for tramming...............  15..........................  Yes.
Training.................................  38..........................  No.
----------------------------------------------------------------------------------------------------------------

    Those requirements in the petitions that were omitted from the 
proposed rule are as follows: limiting the operating voltage of the 
continuous mining machine; limiting the number of splices in a high-
voltage trailing cable; prohibiting permanent tape-type splices; and 
training requirements for miners on the high-voltage continuous mining 
machine systems. The proposed rule does not limit the continuous mining 
machine voltage, originally specified by the manufacturer to 2,400 
volts, because existing regulations in Part 18 allow for approval of 
equipment up to 4,160 volts. The proposed rule, like the high-voltage 
longwall rule, has technical provisions to test and evaluate equipment 
containing on-board switching of high-voltage components up to 4,160 
volts. Therefore, we believe that limiting the maximum operating 
voltage of continuous mining machines to 2,400 volts would 
unnecessarily restrict the design, and have written the proposed rule 
to allow for approval of equipment with operating voltages up to 4,160 
volts.
    The proposed rule does not include a limit in the number of splices 
in a high-voltage trailing cable because we could find no data to 
support quantifying a maximum number. The design features of the high-
voltage cables combined with the sensitive ground-fault protection of 
the circuit will dictate increased vigilance in the protection and 
maintenance of the high-voltage cables. Our experience has shown that 
as a splice is added to a high-voltage trailing cable, leakage current 
may flow between the phase conductors and the shielding and grounding 
conductors in the splice. These leakage currents would occur inside the 
splice, and would not pose a shock hazard to miners. As additional 
splices are added, the summation of these currents will activate the 
sensitive ground-fault protection and prevent the continuous mining 
machine from operating.
    Additionally, while we prohibited the use of permanent tape-type 
splices under the petitions, we do not prohibit such use in this 
proposed rule. Tape-type splices can be used to make an effective 
splice when proper procedures are followed. Our concern with allowing 
them had been that the splice materials were often used improperly, and 
this allowed moisture to enter the splice. Moisture would then degrade 
the insulation and ultimately create a shock hazard. Instead of 
prohibiting all tape-type splices, we are proposing that all splices be 
made with an MSHA-approved splice kit. The approved kits contain 
materials and instructions on the proper methods for making a splice. 
The kit includes tape that is self-vulcanizing so it will exclude 
moisture when applied as instructed, thereby preventing a shock hazard.
    Finally, the PFMs required certain safety training that is already 
required by 30 CFR part 48, and, therefore was duplicative. 
Specifically, all miners who perform maintenance on high-voltage 
continuous mining machines are to be trained in high-voltage safety, 
testing, and maintenance procedures. Also, all personnel who work in 
the proximity of the high-voltage continuous mining machine or who move 
high-voltage equipment or cables are to be trained in high-voltage 
safety procedures. These requirements are not incorporated into the 
proposed rule since they are already required under existing 30 CFR 
part 48.

IV. Discussion of the Proposed Rule

A. General Discussion--Part 18 Electric Motor-Driven Mine Equipment and 
Accessories

    We are proposing to add specific design requirements for high-
voltage continuous mining machines used in face areas and pillar 
workings of underground mines for manufacturers to follow to obtain our 
approval. The proposed additional requirements would allow high-voltage 
switchgear with enhanced safety protection from fire, explosion and 
shock hazards to be used on high-voltage continuous mining machines. 
The proposed changes would accomplish several purposes. They would 
improve the design requirements for continuous mining machines 
consistent with existing requirements in 30 CFR part 18, accommodate 
new design technology that is practical, and lessen burdens on the 
mining community while preserving safety and health protection for 
miners.
    The main safety protections addressed in this proposed rule, like 
the high-voltage longwall rule, are summarized into four areas: (1) 
Prevention of a high-voltage arc from occurring; (2) prevention of the 
resulting heat or flame from igniting a methane-air mixture surrounding 
the machine if an arc or methane explosion occurs within the explosion-
proof enclosure; (3) prevention of enclosure failure from an increased 
pressure rise if an arc or methane explosion occurs within the 
explosion-proof enclosure; and (4)

[[Page 42815]]

personal protection for miners from electrical shock hazards when 
working with or around the high-voltage equipment.
    This proposed rule addresses only those provisions of 30 CFR part 
18 for approval of continuous mining machines with onboard high-voltage 
switching of high-voltage components. Several of these proposed 
provisions are either new or derived from existing part 18 
requirements. However, we are also proposing a number of requirements 
identical to existing Sec.  18.53 provisions for longwall mining 
systems that also apply to high-voltage continuous mining machines. We 
have chosen to organize the rule so that the requirements for approval 
of continuous mining machine systems remain separate from those of 
longwall systems. We invite comments on whether we should reorganize 
Sec. Sec.  18.53 and 18.54 to combine them or reorganize them in some 
other way in the final rule.
    We are proposing this approval rule (30 CFR part 18) in conjunction 
with mandatory safety standards for high-voltage continuous mining 
machines (30 CFR part 75).

B. General Discussion--Part 75 High-Voltage Continuous Mining Machine 
Safety Standards

    We have evaluated the safety of high-voltage continuous mining 
machines used in underground coal mines for approximately six years. 
Through the petition process that allows a mine operator to request 
modification of a safety standard at a particular mine, we have 
performed specific on-site investigations for all petitions granted for 
the use of high-voltage continuous mining machines. We have verified 
that safety concerns of explosion, fire, and shock hazards associated 
with the use of high-voltage have been sufficiently addressed by 
advances in the high-voltage technology. For example, we have 
recognized that high-voltage electric equipment and circuit design 
improvements in combination with sensitive electrical circuit 
protections reduce the potential for fire, explosion and shock hazards. 
We have noted the availability of lighter power cables that reduce back 
strain and other injury risks to miners often associated with moving, 
lifting, or hauling the heavier lower voltage cables. Moreover, to our 
knowledge, there have been no electrical fatalities resulting from 
using high-voltage equipment under granted petitions. Our evaluation 
reveals that high-voltage continuous mining machines can be safely 
used, provided certain conditions are met.
    Accordingly, we are proposing to revise the existing 30 CFR part 75 
electrical safety standards to permit the use of high-voltage 
continuous mining machines. We have included new safety provisions, as 
well as almost all the basic provisions from granted petitions relative 
to the proper installation, electrical and mechanical protection, 
handling, and procedures for disconnecting circuits and equipment.
    This proposed rule would not reduce the protection afforded by 
existing 30 CFR part 75 standards. Rather, it would provide increased 
protection from electrical, fire, and other hazards. We are proposing 
revisions to part 75 in conjunction with proposed revisions to 30 CFR 
part 18 that would address approval requirements for high-voltage 
continuous mining machines.

C. Plain English

    We have attempted to write this proposed rule and preamble so that 
it is clear and understandable. In addition to the specific comments we 
are requesting throughout this preamble including those above 
concerning proposed Sec.  18.54, we invite comments on how to make the 
entire rule easier to understand. For example:
    1. Have we organized the material to suit your needs? If not, how 
could the material be better organized?
    2. Do we clearly state the requirements in the rule? If not, how 
could the rule be more clearly stated?
    3. Is the technical language clear? If not, what language requires 
clarification?
    4. Would a different format (grouping or order of sections, use of 
headings, paragraphing) make the rule easier to understand? If so, what 
changes to the format would make the rule easier to understand?

D. Section-by-Section Discussion

Part 18 Electric Motor-Driven Mine Equipment and Accessories

Section 18.54 High-Voltage Continuous Mining Machines

(a) Separation of High-Voltage Components From Lower Voltage Components
    Proposed paragraph (a) of this section was derived from existing 
Sec.  18.53(a). The existing requirements for high-voltage longwall 
equipment are contained in Sec.  18.53, High-voltage longwall mining 
systems. It would require separation of low- and medium-voltage 
circuits from those with high-voltage circuits in each motor-starter 
enclosure, by separate compartments, barriers, or partitions. Barriers 
and partitions, under this proposed rule, like the high-voltage 
longwall rule, would have to be constructed of grounded metal or 
nonconductive insulating board. When designing the barriers or 
partitions, consideration should be given to possible effects of 
pressure-piling within the enclosure due to restricted configurations 
within enclosures. Such restrictions can cause an accelerated rate of 
burning of a methane-air mixture that can create abnormal pressures 
within the enclosure. This extreme pressure can cause the enclosure to 
fail and possibly ignite methane gas or coal dust surrounding the 
enclosure, thereby putting miners at risk. The proper design of 
enclosures, including placement of barriers and partitions can limit 
the damaging effects from pressure piling. Under this proposed rule, 
barriers, partitions, or separate compartments must be provided between 
high-voltage and lower-voltage compartments to protect persons from 
coming into contact with energized high-voltage conductors or parts 
such as when testing and troubleshooting low- and medium-voltage 
circuits on the continuous mining machine.
(b) Interlock Switches
    Proposed paragraph (b) of Sec.  18.54 would require covers or 
removable barriers or partitions of motor-starter enclosure 
compartment(s) containing high-voltage components to be provided with 
at least 2 interlock switches. Proposed paragraph (b) is derived from 
existing Sec.  18.53(b) with the addition of the word ``removable'' to 
clarify that interlock switches would not be required on permanently 
installed barriers, or partitions. Interlock switches protect miners 
entering enclosures from shock hazards by de-energizing high-voltage 
circuits when these barriers, partitions, or covers are removed. Like 
the high-voltage longwall rule, a minimum of two interlock switches per 
cover would be required and must be wired into the circuitry so that 
operating either switch would de-energize the incoming high-voltage 
circuits to that enclosure.
(c) Circuit-Interrupting Devices
    Proposed paragraph (c) of Sec.  18.54 is derived from the 
requirements in the granted PFMs for the use of high-voltage continuous 
mining machines and is identical to Sec.  18.53(c). It would require 
that circuit-interrupting devices be designed and installed to prevent 
automatic reclosure. This provision would protect against shock, fire, 
and explosion hazards. For example, if a roof fall or equipment 
insulation failure

[[Page 42816]]

were to result in a short-circuit or ground-fault condition, the 
automatic reclosing of circuit-interrupting devices would re-energize 
the circuit and could create a hazard to miners.
(d) Transformers Supplying Control Voltages
    Proposed paragraph (d) is primarily derived from existing Sec.  
18.53(d), but incorporates changes based on our experience in enforcing 
that provision. The proposed changes would clarify the grounding 
requirements of the electrostatic shield for various transformer 
designs.
    Proposed paragraph (d)(1) of this section would require that the 
nominal control voltage of alternating-current circuits not exceed 120 
volts line-to-line. This requirement would allow any appropriate 
control circuit wiring configuration of 120 volts line-to-line or less 
to exist, and would be consistent with the high-voltage longwall rule 
and granted petitions for high-voltage continuous mining machines. 
Limiting the control voltages to 120 volt, line-to-line will reduce the 
potential for electrocution hazards to miners.
    Proposed paragraph (d)(2) specifies that control transformers with 
high-voltage primary windings that are located in each high-voltage 
motor-starter enclosure or that supply control power to multiple motor-
starter enclosures, have an electrostatic (Faraday) shield installed 
between the primary and secondary windings. After the high-voltage 
longwall rule was promulgated, we became aware of the different control 
transformer designs which affect how electrostatic shields are 
grounded. Proposed paragraphs (d)(2)(i) and (ii) address those 
different grounding methods.
    The purpose of the electrostatic shields is to provide isolation 
between the high-voltage and lower-voltage circuit(s). This isolation 
would protect miners against high-voltage shock hazards should a fault 
develop between the primary and secondary windings. Electrostatic 
shielding would also prevent transients (sudden short term changes in 
voltage and current) occurring on the primary circuit from being 
transferred to the secondary circuit. Such transients could cause 
premature damage to electrical and electronic control equipment and 
create an economic burden for the mining industry.
    Grounding of the electrostatic shield would be dependent on the 
design of the transformer. If a transformer is designed with an 
external grounding terminal, proposed paragraph (d)(2)(i) would require 
the shield to be connected to the equipment ground by a minimum of a 
No. 12 American Wire Gauge (A.W.G.) grounding conductor extending from 
the external grounding terminal. This minimum wire size requirement is 
intended to ensure proper current carrying capacity and mechanical 
strength of the grounding conductor.
    Proposed paragraph (d)(2)(ii) would require that if the transformer 
is designed without an external terminal, the electrostatic shield 
would have to be connected to the transformer frame by an internal 
conductor. This conductor, installed when the transformer was 
manufactured, would be considered an extension of the shield, and 
therefore, could be smaller than a No. 12 A.W.G. In this case, bolting 
of the transformer frame to the equipment enclosure would provide the 
required path to ground, as long as an effective low impedance 
electrical connection is maintained.
(e) Onboard Ungrounded, Three-Phase Power Circuit
    The provisions of proposed paragraph (e) of this section are 
derived from the granted PFMs for the use of high-voltage continuous 
mining machines. Proposed paragraph (e) would require a grounded-phase 
indicator light when three-phase, ungrounded power circuits are used 
onboard the continuous mining machine. These circuits include high-
voltage transformers on-board the machine to power low- and medium-
voltage circuits. The secondary windings of these transformers are 
connected in an ungrounded configuration. The purpose of requiring an 
indicator light would be to detect or alert the operator to grounded-
phase conditions in the ungrounded circuits. With ungrounded systems, 
the capacitive coupling between each phase conductor and ground can 
subject the ungrounded system to dangerous overvoltages resulting from 
intermittent ground faults. The occurrence of a second grounded-phase 
would create a short-circuit and possible arcing between components. 
This could result in a methane-air explosion that could result in 
catastrophic failure of the enclosure or cause a shock hazard to 
miners. Therefore, it is important to detect and immediately correct 
any grounded-phase condition to prevent a hazard. Paragraphs (e)(1) 
through (e)(3) address these concerns.
    Proposed paragraph (e)(1) would require an on-board grounded-phase 
indicator light to alert the machine operator if a grounded-phase 
condition were to occur on any ungrounded, three-phase power circuit.
    Proposed paragraph (e)(2) would require the indicator light to be 
installed so that the machine operator could readily observe it from 
any location where the continuous mining machine is normally operated.
    Proposed paragraph (e)(3) would require that the onboard 
ungrounded, three-phase power circuit contain a test circuit to verify 
the integrity and proper operation of the grounded-phase detection 
circuit. Also, the test circuit must be designed so that (1) the 
designated person would not have to remove the electrical enclosure 
covers to activate it; and (2) it would not create a double-phase-to-
ground fault resulting in a short-circuit condition. We note that such 
a design already exists, as we have seen equipment where a readily 
accessible test switch was used to activate the test circuit and not 
require the removal of electric enclosure covers. This design would 
minimize hazards to personnel by making the test easier to use and 
avoid placing personnel in close proximity to exposed, energized 
conductors, thereby minimizing the potential for shock hazards.
(f) High-Voltage Trailing Cable(s)
    Proposed paragraph (f) would address high-voltage trailing cables, 
and is derived from: the granted PFMs for the use of high-voltage 
continuous mining machines; proposed Sec.  75.826; existing Sec. Sec.  
18.35 and 18.47; and Insulated Cable Engineer's Standards (ICEA)S-75-
381/National Electrical Manufacturer's Association (NEMA) Standard NEMA 
WC 58-1997. The proposed rule incorporates by reference the current 
carrying capacity (ampacity) ratings and outside diameter requirements 
for trailing cables listed in the ICEA/NEMA Standard. This requirement 
would standardize the ampacity and outer diameter of cables to prevent 
overheating and ensure the interchangeability of trailing cables 
provided by different manufacturers. In accordance with the 
requirements for incorporating by reference, proposed paragraph (f) 
details how the public may inspect or purchase a copy of the 
incorporated standard and notes that according to his/her statutory 
authorization, the Director of the Federal Register has approved the 
incorporation by reference.
    Existing Sec.  18.35 contains general requirements, such as minimum 
conductor size, maximum cable length, flame resistance, etc., for 
trailing cables. Existing Sec.  18.47(d)(5) addressing voltage 
limitations of trailing cables requires cables to include grounding 
conductors, a ground check conductor, and grounded metallic shields 
around each

[[Page 42817]]

power conductor. Proposed paragraphs (f)(1), (f)(2), (f)(3), and (f)(4) 
would specify requirements applicable to trailing cables for high-
voltage continuous mining machines.
    Specifically, proposed paragraph (f)(1) would require trailing 
cables to be constructed to include 100 percent semi-conductive tape 
shielding over each insulated power conductor. Proposed paragraph 
(f)(2) would require a grounded metallic braid shielding over each 
power conductor. The 100 percent semi-conductive tape shielding 
material and grounded metallic shield around each power conductor would 
protect miners from shock and electrocution hazards. Also, the 
combination of the tape and shielding requirements would prevent 
voltage stresses on the conductor insulation. The shielding maintains a 
symmetrical distribution of voltage stresses. This is critical at 
higher operating voltages. Shielding also prevents transients on power 
systems and reduces the hazard of electric shocks.
    Proposed paragraph (f)(3) of this section would require that the 
cable include either a ground check conductor not smaller than a No. 10 
A.W.G. or a center ground-check conductor not smaller than a No. 16 
A.W.G. stranded conductor. Cables designed with a center ground-check 
conductor do not need to have the size of the ground-check conductor as 
large as a ground-check conductor located on an interstice of the cable 
since the conductor would be exposed to less mechanical stress and 
damage. Therefore, a No. 16 A.W.G. ground-check conductor would be 
adequate. Such designs have been used in high-voltage longwall 
applications for several years, and are currently permitted under 
existing Sec.  75.822.
    Proposed paragraph (f)(4) of this section is based on language 
contained in granted PFMs for the use of high-voltage continuous mining 
machines. It would require the use of two reinforced layers of jacket 
material. Under this construction, the inner-most layer of two-layered 
protective cable jacket would be required to be a color distinctive 
from the outer jacket color. This requirement would also complement the 
inspections required in proposed Sec.  75.832(d) since the purpose 
would be to allow for easy recognition of damage to the jacket. The 
provision would not permit the color black to be used for either layer 
since it would be hard to identify damaged areas.
(g) Safeguards Against Corona
    Proposed paragraph (g) of Sec.  18.54 is identical to existing 
Sec.  18.53(k). Proposed paragraph (g) would require a manufacturer to 
provide safeguards against corona on all 4,160 volt circuits in 
explosion-proof enclosures. Corona is a luminous discharge that occurs 
around electric conductors that are subject to high electric stresses. 
Corona can cause premature breakdown of insulating materials in 
explosion-proof enclosures onboard the high-voltage continuous mining 
machine. This could result in arcing and possibly create an explosion 
hazard. Although corona usually does not present a hazard until a 
voltage of 8kV is reached, safeguards should be taken at 4,160 volts. 
Safeguards would include using cables with a corona resistant 
insulation such as ethylene propylene to avoid small nicks or cuts in 
the cable insulation and to minimize high-voltage transients. As with 
the high-voltage longwall rule, this provision is not intended to 
require stress cones or similar termination schemes to prevent corona.
(h) Explosion-Proof Enclosure Design
    Proposed paragraph (h) of this section is identical to existing 
Sec.  18.53(l). It would require limiting the maximum explosion 
pressure rise within an enclosure to 0.83 times the design pressure for 
any explosion-proof enclosure containing high-voltage switchgear. This 
requirement would protect against explosion hazards that may arise from 
the effects of a sustained high-voltage arcing fault. Arcing faults may 
significantly contribute to a pressure rise in an explosion-proof 
enclosure during an internal methane-air explosion. A pressure rise 
above the design limit of the enclosure could cause the explosion-proof 
enclosure to fail to contain the methane explosion.
(i) Location of High-Voltage Electrical Components Near Flamepaths
    Proposed paragraph (i) is identical to existing Sec.  18.53(m). It 
would require that high-voltage electrical components located in high-
voltage explosion-proof enclosures not be coplanar with a single-plane 
flame-arresting path. This protective measure would prevent the heat or 
flame (from an arc or methane explosion in an explosion-proof 
enclosure) from igniting a methane-air mixture surrounding the 
enclosure. This requirement would prevent the possibility of conductor 
material particles from being expelled from the enclosure through the 
flame-arresting path. Particles of molten material are emitted from the 
conductors whenever an arcing short-circuit occurs in an explosion-
proof enclosure. Expulsion of these particles from the enclosure can 
occur if their source is in the same plane as the flame-arresting path 
and a pressure rise coincides with the short circuit. Once these 
particles are expelled from the explosion-proof enclosure, they can 
ignite an explosive atmosphere should one be present. This possibility 
would not arise with multi-plane flame-arresting path surfaces because 
a deflection in the path would prevent ignitions by expelled particles.
(j) Minimum Creepage Distances
    Proposed paragraph (j) of Sec.  18.54, including the table for 
minimum creepage distances, is identical to existing Sec.  18.53(n). 
Proposed paragraph (j) would require that rigid insulation between 
high-voltage terminals or between high-voltage terminals and ground be 
designed with creepage distances in accordance with the minimum 
creepage distance table proposed in this section. The minimum creepage 
distances specified would provide adequate insulation to prevent a 
phase-to-phase or phase-to-ground fault that could cause a possible 
explosion. The required creepage distances are determined based upon 
the phase-to-phase use voltage and the Comparative Tracking Index (CTI) 
of the insulation to be used. An appropriate method of determining the 
CTI of the electrical insulating material is described in the American 
Society for Testing and Materials Standard, ASTM D3638 ``Standard Test 
Method for Comparative Tracking Index of Electrical Insulating 
Materials.'' The MSHA derived creepage distances in the table are 
consistent with most commercially available high-voltage components to 
which this provision would apply.
(k) Minimum Free Distances
    Proposed paragraph (k) of Sec.  18.54, including the table 
discussing Minimum Free Distances (MFDs), is identical to existing 
Sec.  18.53(o). It would address a requirement for MFDs within an 
explosion-proof motor-starter enclosure. During development of the 
high-voltage longwall rule, we determined that if phase-to-phase arcing 
occurred, there might be sufficient arc energy to heat the walls of the 
enclosure beyond the safe design temperature. This could cause failure 
of the enclosure and create an explosion hazard if the MFDs are below 
what is specified in the table. Consequently, distances between the 
wall or cover of an enclosure and uninsulated electrical conductors 
inside the enclosure were established to prevent wall or cover damage 
that may result from phase-to-phase arcing.
    Under proposed paragraph (k)(1), we would allow for values not 
specified in the MFD table provided they meet the

[[Page 42818]]

specific engineering formulas on which the table is based. These 
formulas are adopted from existing Sec.  18.53. Under proposed 
paragraph (k)(2), we would require the minimum free distance values in 
the table or those values calculated using the prescribed formula to be 
increased by an incremental amount based on the system voltage. The 
minimum free distance must be increased by 1.5 inches for 4160 volt 
systems and by 0.7 inches for 2400 volt systems when the adjacent wall 
area is at the top of the enclosure. This increase in distance is 
necessary to account for the thermal effects caused from the arc, due 
to heat rising within the enclosure. Under this proposed paragraph we 
would also consider the use of steel shields in conjunction with an 
aluminum wall or cover. Under these circumstances, the thickness of the 
steel shield would be used to determine the minimum free distance.
    Additionally, we would consider the use of alternate techniques and 
methods, as permitted by Sec.  18.47(d)(6), that preclude the 
possibility of high-energy arcs that would heat the walls of explosion-
proof enclosures beyond safe temperatures. If upon evaluation, 
equivalent safety were demonstrated, we would accept these 
technological advances and the results of additional research in this 
area.
(l) Static Pressure Testing of Explosion-Proof Enclosures Containing 
High-Voltage Switchgear
    Proposed paragraph (l) of this section is derived from existing 
Sec.  18.53(p). Proposed paragraph (l)(1) would require that prior to 
performing explosion tests required under existing Sec.  18.62, the 
manufacturer must perform a static pressure test as detailed in 
proposed paragraph (l)(1)(i) on each prototype design of explosion-
proof enclosure housing high-voltage switchgear and the enclosure meet 
acceptable performance criteria as specified in proposed paragraph 
(l)(1)(ii).
    Proposed paragraph (l)(1)(i) describes the prototype static test 
procedure and specifies that the enclosure be internally pressurized to 
a pressure no less than the design pressure, with the pressure 
maintained for a minimum of 10 seconds. The pressure is then released 
and the pressurizing agent removed from the enclosure. We have 
developed the static pressure test with its acceptable performance 
criteria to ensure each enclosure design would be capable of 
withstanding its design pressure. By requiring static pressure testing 
on each prototype enclosure, we believe that the adequacy of enclosure 
design would be verified.
    Proposed paragraph (l)(1)(ii) specifies the acceptable performance 
criteria that enclosures undergoing the prototype static pressure test 
must satisfy. Acceptable performance would be achieved if the 
enclosure, during pressurization, did not result in the rupture of any 
part that would affect the integrity of the explosion-proof enclosure 
or cause leakage through welds or castings. Further, the provision 
would require that following removal of the pressurizing agents, the 
enclosure would not exhibit visible cracks in welds, permanent 
deformation exceeding 0.040 inches per linear foot; or excessive 
clearances along flame-arresting paths following retightening of 
fastenings, as necessary. Any of these conditions would constitute 
unacceptable performance because they would indicate that the 
explosion-proof integrity of the enclosure has been compromised.
    Proposed paragraph (l)(2) would require the manufacturer of every 
explosion-proof enclosure housing high-voltage switchgear to either 
conduct the static pressure test for each manufactured unit or follow 
an MSHA-accepted quality assurance procedure covering the inspection of 
the enclosure. These procedures are typically required by nationally 
recognized quality systems certification organizations. The purpose of 
the quality assurance procedures would be to verify that the 
manufactured enclosure meets the design specifications of the original 
enclosure tested.

Part 75--Mandatory Safety Standards--Underground Coal Mines

Section 75.823 Scope

    Proposed Sec.  75.823 describes the scope of this proposed rule. 
Proposed Sec. Sec.  75.824 through 75.833 are electrical standards that 
would apply only to the use of high-voltage continuous mining machines. 
Proposed Sec.  75.823 also specifies that under this rule a ``qualified 
person'' means a person qualified under existing Sec.  75.153; 
Electrical work; qualified person. This requirement is derived from 
existing Sec.  75.820(a), and is included in the scope to prevent 
repetition of this requirement. Consequently, any reference in this 
proposed rule to electrical work on circuits and equipment associated 
with high-voltage continuous mining machines would need to be performed 
by persons qualified in accordance with Sec.  75.153. This electrical 
work includes all circuits and equipment, not just high-voltage.
    Also, this proposed rule is similar to the high-voltage longwall 
rule in that non-qualified persons working under the direct supervision 
of a qualified person would not be permitted to do electrical work, 
even when directly supervised by a qualified person. We believe that 
when a person is qualified to perform electrical work on low-, medium-, 
and high-voltage circuits, he is able to identify hazards and follow 
safe work procedures. Therefore, only qualified persons would be 
permitted to work on circuits associated with high-voltage continuous 
mining machines. This requirement is intended to prevent electrical 
accidents.
    Other standards in 30 CFR would also apply to this equipment, where 
appropriate. For example, safety standards, such as grounding and 
ground-monitor requirements contained in subparts H and I of part 75 
that are currently applicable to high-voltage installations are also 
applicable to high-voltage continuous mining machines. However, 
Sec. Sec.  75.813 through 75.822 apply only to high-voltage longwalls. 
Additionally, once promulgated, this rule will supercede existing 
provisions from granted PFMs.

Section 75.824 Electrical Protection

    Proposed Sec.  75.824, with the exception of paragraph (a)(2)(ii), 
is derived from the granted PFMs for the use of high-voltage continuous 
mining machines. Proposed Sec.  75.824 addresses electrical protection 
for high-voltage continuous mining machines. The effects of ground 
faults, overloads, electrical arcing, heating of conductors, and short 
circuits can have adverse consequences to the safety of miners. 
Effective electrical protection for continuous mining machines would 
reduce the potential for ignitions, fires, and miner exposure to 
energized equipment frames. The proposed rule would provide increased 
miner protection by incorporating the latest technology when using 
high-voltage continuous mining machines.
(a) Trailing Cable Protection
    Proposed paragraph (a) of Sec.  75.824 would require that a 
circuit-interrupting device have adequate interrupting capacity and be 
rated for the maximum voltage of the circuit in which it is used. The 
device would be part of the short-circuit, overload, ground-fault, and 
undervoltage protection for the trailing cable and the mining machine.
    The purpose of requiring that the circuit-interrupting device be 
properly rated is to safely interrupt any circuit current in which it 
is intended to be used without damage to itself. The circuit-
interrupting device must have a voltage rating that would ensure that 
the device would remain undamaged when

[[Page 42819]]

subjected to the maximum voltage of the system. Short-circuit and 
overload protection prevent damage to cables and motors due to arcing 
and overheating, and, therefore, minimize the risk of ignition and fire 
hazards to miners. Ground-fault protection minimizes the risk of shock 
and electrocution hazards to miners. Undervoltage protective devices 
prevent automatic restarting of equipment following a loss of power. 
This would prevent the inadvertent movement of machinery that can place 
miners at risk.
(1) Short-Circuit Protection
    Proposed paragraph (a)(1)(i) would specify a current setting for a 
short-circuit protective device. The device, located in the power 
center, would be required to be set at the lower value of either the 
setting specified in approval documentation pertaining to the 
continuous mining machine or 75 percent of the minimum available phase-
to-phase short-circuit current at the continuous mining machine. The 
short-circuit current settings specified in our approval documentation 
are based on the design of the continuous mining machine. As equipment 
is used and moved from one location to another in a mine, changes may 
take place in the electrical system which require an adjustment to the 
short-circuit protective device setting.
    Proposed paragraph (a)(1)(ii) would allow the short-circuit device 
protecting the cable extending from the power center to the continuous 
mining machine to have an intentional time delay. The short-circuit 
protective device located in the power center would be required to have 
the lower value of either the time delay setting specified in the 
approval documentation or up to 0.05 seconds.
    The purpose of permitting a time delay is to eliminate nuisance 
tripping during motor starting. When high-voltage longwalls were 
introduced to the mining industry, nuisance tripping problems were 
experienced. This nuisance tripping was caused by motor starting 
currents. To solve these problems, it was necessary to incorporate time 
delays into the short-circuit protective devices. Currently, electronic 
relays that are commonly used to provide short-circuit protection for 
high-voltage continuous mining machine circuits are designed with 
inherent time delay to override motor starting currents.
(2) Ground-Fault Protection
    Proposed paragraph (a)(2) of Sec.  75.824 would require ground-
fault protection for the trailing cable extending from the power center 
to the continuous mining machine. Proposed paragraph (a)(2)(i) would 
require ground-fault currents to be limited by a neutral grounding 
resistor to not more than 0.5 ampere. Neutral grounding resistors are 
used in resistance grounded systems to limit the level of ground fault 
current in a circuit. The use of a 0.5 ampere neutral grounding 
resistor in conjunction with the ground-fault devices specified in the 
proposed standard would reduce the potential for shock hazards and 
prevent the neutral grounding resistor from overheating and becoming a 
fire hazard.
    Proposed paragraph (a)(2)(ii) would require the trailing cable 
extending to the continuous mining machine to be protected by a ground-
fault device set at not more than 0.125 ampere. The 0.125 ampere limit 
is based on the fact that sensitive ground-fault devices are 
commercially available and have been successfully used to detect 
ground-fault currents in circuits with extremely large values of motor 
starting current. The ground-fault device would have to operate within 
0.050 second when exposed to 0.125 or more ampere. The purpose of 
permitting a time-delay is to prevent nuisance tripping during motor 
starting. The proposed time-delay requirement of paragraph (a)(2)(ii) 
is new.
    The granted PFMs require instantaneous ground-fault protection, and 
do not allow for any time delay. However, with higher inrush currents, 
the lower settings of the relay may cause the circuit to open during 
motor starting.
    Proposed paragraph (a)(2)(iii) of Sec.  75.824 would require an 
impedance-measuring ``look-ahead'' circuit to detect a ground-fault 
condition and prevent the closing of a circuit-interrupting device when 
a ground-fault exists in a circuit. The practice of repeatedly closing 
the circuit-interrupting device with a fault present can cause the 
circuit-interrupting device insulation to fail and cause the device to 
explode. This requirement is intended to reduce possible injury to 
miners from such potential explosion.
    Proposed paragraph (a)(2)(iv) of Sec.  75.824 would require that a 
high-voltage circuit extending from the power center to the continuous 
mining machine have back-up ground-fault protection to detect an open 
neutral grounding resistor. The back-up ground-fault protective device 
can be a combination of a potential transformer and voltage relay, or 
any other device capable of detecting an open neutral grounding 
resistor. Once an open neutral grounding resistor is detected, the 
back-up device must cause the circuit extending from the power center 
to the continuous mining machine to be de-energized. The 40 percent 
trip level would provide a safety factor to ensure that unexpected 
lower levels of ground-fault current would be detected and cause the 
circuit-interrupting device to open. Additionally, the back-up device 
must have a time-delay setting of not more than 0.25 second. The time-
delay setting would be low enough to ensure quick de-energization of 
the circuit when the neutral resistor opens and a ground-fault exists, 
while allowing for selective tripping with the ground-fault protective 
device of the trailing cable.
    Proposed paragraph (a)(2)(v) of Sec.  75.824 would require thermal 
protection for the high-voltage neutral grounding resistor that would 
open the ground-wire monitor for the high-voltage circuit supplying the 
power center if the neutral grounding resistor is subjected to high-
temperature resulting from a sustained ground-fault current. Thermal 
protection could include current transformers and thermal relays or any 
other devices, such as thermostats that sense overtemperature. The 
thermal device must not depend on control power because a loss of 
control power could prevent the detection devices from operating. The 
overtemperature rating or setting of the device would be the lower 
value of either 50 percent of the maximum temperature rise of the 
neutral grounding resistor or 302[deg] F (150[deg] C).
    A thermal device is an added safety feature which would cause 
interruption of the high-voltage circuit supplying the power center by 
opening the ground-wire monitor circuit before sustained extreme heat 
causes the neutral grounding resistor to fail in the open mode. Failure 
of the resistor could leave the circuit unprotected against ground 
faults and would increase the possibility of fire and shock hazards. 
The proposed overtemperature setting requirement would ensure that the 
affected circuit is quickly de-energized under a sustained fault. Our 
experience has been that the settings specified would be high enough to 
prevent nuisance tripping.
    Proposed paragraph (a)(2)(vi) of Sec.  75.824 would require a 
single window-type current transformer to encircle the three-phase 
conductors for ground-fault protection. It would also prohibit the 
equipment grounding conductors from being passed through the ground-
fault current transformer. This configuration would be prohibited 
because it would defeat ground-fault protection and result in hazardous 
voltage on equipment frames. Using the single-window type current 
transformer

[[Page 42820]]

in conjunction with a ground-fault relay would ensure sensitive ground-
fault protection for circuits extending from the power center to the 
continuous mining machine.
    Proposed paragraph (a)(2)(vii) would require a ground-fault test 
circuit for each ground-fault device specified in proposed paragraph 
(a)(2)(ii) of this section. This test circuit would be required to 
inject a current of 50 percent or less of the current rating of the 
neutral grounding resistor to verify that a ground-fault condition will 
cause the corresponding circuit-interrupting device to open. This test 
procedure would help determine if ground-fault devices function at 
required current levels. It would also test the sensitivity of each 
device to ground fault currents.
(3) Undervoltage Protection
    Proposed paragraph (a)(3) of this section would require that the 
undervoltage device operate on a loss of voltage, de-energize the 
circuit, and prevent the equipment from automatically restarting. This 
provision is performance oriented. It would permit any undervoltage 
protective device that operates on loss of voltage and which prevents 
the automatic closing of the circuit-interrupting device upon 
restoration of power, to be used. This requirement is intended to 
reduce the likelihood that miners will be pinned or crushed due to the 
automatic restarting of the equipment upon restoration of power.
(b) Reclosing
    Proposed paragraph (b) of Sec.  75.824 would prohibit the use of 
circuit-interrupting devices that automatically reclose after opening. 
Automatic reclosure of the circuit-interrupting device would allow a 
circuit that has sustained a fault to re-energize. Typically, faults 
occur in trailing cables as a result of damage from roof falls or 
equipment. Under such circumstances, the use of automatic reclosing 
circuit-interrupting devices could create shock and fire hazards if the 
devices were designed to automatically reclose when a short-circuit or 
ground-fault condition exists in the circuit.
(c) Onboard Power Circuits
    Proposed paragraph (c) of Sec.  75.824 would require a mine 
operator to implement certain procedures if a grounded-phase indicator 
light was provided on a high-voltage continuous mining machine, and it 
indicated a grounded-phase condition.
    The purpose of proposed paragraph (c) would be to warn miners of a 
grounded-phase condition. With ungrounded systems, the capacitive 
coupling between each phase conductor and ground can subject the 
ungrounded system to dangerous overvoltages from intermittent ground 
faults which can lead to insulation failure. Insulation failure can 
lead to another phase-to-ground failure. When two phases are grounded, 
a double-phase-to-ground or short-circuit condition will occur. High 
fault current will travel through the continuous mining machine frame 
creating possible shock and arcing hazards. The indication of a 
grounded-phase condition and subsequent repair of the equipment would 
reduce shock hazards to miners and eliminate any arcing ground-fault 
which can be an ignition source for methane. Therefore, it is important 
to detect and correct any grounded-phase condition.
    Proposed paragraphs (c)(1) and (2) of this section set out safe 
procedures to be followed when locating and correcting a grounded-phase 
condition. Proposed paragraph (c)(1) requires that once the grounded-
phase indicator light on the high-voltage continuous mining machine 
shows that a grounded-phase fault has occurred, the mining machine must 
be immediately moved to an area where the roof is supported. Proposed 
paragraph (c)(2) requires that once a grounded-phase fault has 
occurred, the machine not be placed into operation until the grounded-
phase condition is corrected or the machine be taken out of service. 
The intent of proposed paragraph (c)(1) is to minimize miners' exposure 
to roof falls while the equipment is being repaired. The intent of 
proposed paragraph (c)(2) is to protect the miners from shock hazards.

Section 75.825 Power Centers

    Except for paragraph (f), each paragraph in this proposed section 
is derived from granted PFMs for the use of high-voltage continuous 
mining machines. This section proposes requirements for power centers 
supplying high-voltage continuous mining machines. The proposed rule 
addresses disconnecting switches and devices, barriers and covers, 
interlocks, emergency stop switches, grounding sticks, and caution 
labels. Compliance with these requirements will prevent shock, fire, 
and explosion hazards.
(a) Main Disconnecting Switch
    Proposed paragraph (a) of this section would require a main 
disconnecting switch in the power center. The purpose of the main 
disconnecting switch is to de-energize the primary windings of all 
power transformers in the power center when the switch is open, except 
for the control power transformer(s) and feed-through circuit(s). This 
will provide a safe means of de-energizing power when performing 
electrical work.
(b) Trailing Cable Disconnecting Devices
    Proposed paragraph (b) would require a disconnecting device for 
each high-voltage output used to power the continuous mining machine. 
Disconnecting devices in power centers facilitate the de-energization 
process prior to performing electrical work. Traditionally, we have 
accepted either a disconnecting switch or cable coupler to satisfy 
lock-out and tagging requirements. This proposed paragraph would ensure 
that disconnecting devices are available for lock-out and tagging 
purposes as required in proposed Sec.  75.831 to avoid exposing miners 
to electrical shock hazards.
(c) Disconnecting Switches
    Paragraphs (c)(1) and (c)(2) of this section would require each 
disconnecting switch to have voltage and current ratings compatible 
with the circuits in which they are used. This requirement would 
prevent insulation failure and overheating resulting from using 
improperly rated switches. Therefore, this requirement would ensure 
that these switches would not create a shock or fire hazard to miners.
    Paragraph (c)(3) of this section would require that the 
disconnecting switch be designed and installed so that one could see, 
without removing any covers, that the contacts of the device are open 
when the switch is in the ``open'' position. The removal of any cover 
to verify that the contacts are open could expose personnel to 
energized high-voltage circuits and could increase the potential for 
shock hazard.
    Proposed paragraph (c)(4) would require the disconnecting switch to 
ground all power conductors on the ``load'' side of the switch when it 
is ``open and grounded.'' This requirement would ensure discharging of 
any existing voltage caused by capacitance between the power conductors 
and ground. It would also ensure that work can safely be performed on 
the electric circuits and equipment. Grounding the circuit would 
prevent shock hazards to miners working on the trailing cable or 
continuous mining machine.
    Proposed paragraph (c)(5) would require that each disconnecting 
switch be designed so that it can only be locked in the ``open and 
grounded'' position. The switch must not have the ability to be locked 
in the closed position because it could delay opening the switch during 
an emergency. This provision in conjunction with proposed Sec.  75.831

[[Page 42821]]

would ensure that the circuit remains de-energized until work is 
completed.
    Proposed paragraph (c)(6) would require a disconnecting switch to 
be capable of interrupting the full-load current without causing damage 
to itself and thereby creating hazardous conditions. Using a switch 
that is not capable of interrupting the full-load current could result 
in its destruction and in injuries to miners from flash burns or flying 
parts. If the switch is not designed for full-load current 
interruption, the proposed rule would require that the switch be 
designed to cause the circuit-interrupting device to de-energize the 
incoming power to the ``line'' side of the switch before the 
disconnecting switch interrupts the circuit.
    Proposed paragraph (c)(7) of Sec.  75.825 would require each 
disconnecting switch to be labeled to identify which circuit it would 
de-energize. We believe that identifying the correct circuit would 
assist miners in ensuring that the proper circuit is de-energized 
protecting them from exposure to electrical hazards.
(d) Barriers and Covers
    Proposed paragraph (d) would require all compartments that provide 
access to high-voltage conductors or parts to have a barrier or cover 
to prevent miners from contacting high-voltage circuits. Therefore, 
low- or medium voltage circuits, including control circuits, must be 
separated by a barrier from high-voltage circuits if they are located 
in the same compartment. If the barrier was made of conductive 
material, it would need to be grounded to the power center frame. All 
control devices, other than those mounted on the high-voltage circuit-
interrupting device, would need to be mounted so that they are 
separated from high-voltage parts. The purpose of this requirement is 
to minimize miners' exposure to high-voltage conductors or parts while 
working on or troubleshooting the control circuit. Miners would be 
protected against shock hazards that could arise from inadvertent 
contact with energized high-voltage circuits.
(e) Main Disconnecting Switch and Control Circuit Interlocking
    Proposed paragraph (e) of this section addresses the interlock 
requirements of the main disconnecting switch with the control circuit. 
The proposed interlock would allow the control circuit in the power 
center to be energized only through an auxiliary switch in the ``test'' 
mode when the main disconnecting switch is in the ``open and grounded'' 
position. When the main disconnecting switch is in the ``open and 
grounded'' position, the power conductors on the load side of the 
disconnecting switch are grounded. The interlocking feature would 
ensure that before the auxiliary switch can be placed in the ``test'' 
position, the main disconnecting switch must be open and grounded. When 
the main disconnecting switch is ``closed,'' the control circuit can 
only be powered through the normal position and the control circuit 
cannot be tested. In the normal position, removal of a cover for 
testing would cause the cover interlock switches to de-energize 
incoming power. These interlock requirements are intended to prevent 
energization of the high-voltage circuits during testing and 
troubleshooting.
(f) Interlocks
    Proposed paragraph (f) of this section is derived from the granted 
PFMs for the use of high-voltage continuous mining machines. The PFM 
provisions included the wording ``cover interlock switches,'' but did 
not specify the number of interlock switches required. Proposed 
paragraph (f) clarifies this by requiring at least two interlock 
switches to be installed on the cover or removable barrier of any 
compartment containing high-voltage conductors or parts. Proposed 
paragraph (f) would also require that the switches be installed so that 
removal of a cover or barrier will cause the switches to de-energize 
high-voltage conductors or parts located behind the removed cover or 
barrier. Magnetic or whisker-type switches are acceptable. Our 
experience with inspecting plunger-operated switches has revealed that 
these switches may stick and not operate effectively after exposure to 
the mine environment. We believe that at least two switches coupled 
with required maintenance under 30 CFR 75.512 would provide the 
necessary protection to any miners (including qualified persons) who 
mistakenly remove a cover or barrier, by ensuring that the high-voltage 
circuits are de-energized whenever a cover is removed. This would 
protect miners from accidental contact with energized high-voltage 
circuits.
    At times, qualified persons may need to remove covers and barriers 
when testing or troubleshooting energized power center control 
circuits. Proposed Sec.  75.825(f) requires that the interlocks on the 
covers or barriers isolating energized high-voltage conductors or parts 
de-energize incoming power. The intent of proposed paragraph (f) 
permits bypassing cover and barrier interlocks that isolate de-
energized high-voltage conductors or parts. To bypass the cover and 
barrier interlocks, proposed paragraph (e)(1) of this section requires 
the qualified person to open the main disconnecting switch and place 
the control circuit auxiliary switch in the test position. This would 
permit the removal of covers or barriers when testing or 
troubleshooting the power center control circuits.
    For proposed paragraph (f) we are also considering revising the 
requirement that interlocks de-energize high-voltage circuits when 
covers and barriers are removed by adding an exception for 
troubleshooting control circuits. We specifically request your comments 
on this.
(g) Emergency Stop Switch
    Proposed paragraph (g) of Sec.  75.825 requires an emergency stop 
switch that is located on the outside of the power center and that 
would de-energize the incoming high-voltage to the power center should 
an emergency arise. We would require that the switch be hard-wired to a 
fail-safe ground-wire monitor. In emergency situations, reliability of 
the stop-switch is critical.
(h) Grounding Stick
    Proposed paragraph (h) would require that the power center be 
equipped with a grounding stick to discharge high-voltage capacitors 
and circuits. Because capacitors are energy storage devices, they 
continue to be energized even after the disconnecting switch is opened. 
Therefore, the use of a grounding stick would ensure that a qualified 
person would not be exposed to energized high-voltage conductors or 
parts. While there is no industry definition, we consider a grounding 
stick to be a live line tool (hot stick) made of either wood or 
fiberglass. To safely discharge the capacitors and parts, we recommend 
a hot stick with a No. 1/0 A.W.G. copper conductor bonded to the tool 
end of the hot stick and to the power center frame. This provision 
would also require a label that identifies the location of the 
grounding stick so that a qualified person can easily find it. The 
grounding stick would be required to be stored in a dry location to 
maintain its effectiveness.
(i) Caution Labels
    Proposed paragraph (i) would require that all compartments 
providing access to energized high-voltage conductors and parts display 
a caution label that warns miners against entering the compartment 
before de-energizing the incoming high-voltage circuits to the 
compartment. It should remind miners that the line side of a 
disconnecting switch remains energized when the switch is opened unless 
the incoming power to the switch is de-energized.

[[Page 42822]]

Section 75.826 High-Voltage Trailing Cables

    Proposed Sec.  75.826 specifies the requirements for high-voltage 
trailing cables. The requirements of this section are derived from 
granted PFMs for the use of continuous mining machines, existing 
Sec. Sec.  75.804 and 75.822, and existing and proposed part 18.
    Proposed paragraph (a) would require that the high-voltage trailing 
cables meet the requirements under Sec.  18.35 and proposed Sec.  18.54 
of this title. Any high-voltage cable used as a trailing cable and 
meeting the design requirements of existing Sec.  18.35 and proposed 
Sec.  18.54, would be permitted to be used with high-voltage continuous 
mining machines.
    Proposed paragraph (b) of this section would provide two options. 
The first option would permit a cable meeting the requirements of 
existing Sec.  75.804. Section 75.804 requires, among other things, the 
use of a ground-check conductor not smaller than a No. 10 A.W.G. The 
reason it requires this minimum size is because the conductor is 
located on the periphery of the cable. When the cable is flexed the 
ground-check conductor is subjected to a larger bending radius that can 
weaken the ground-check conductor and cause it to break or become 
damaged. This option permits a ground-check conductor no smaller than 
the No. 16 A.W.G. to be located in the center of the cable. This design 
does not subject the ground-check conductor to the same stresses as the 
first option when the cable is flexed. The main advantage to this 
design versus the existing design in Sec.  75.804 is the reduction of 
inter-machine arcing because the cable design contains three grounding 
conductors placed symmetrically. We have seen this cable design 
successfully used with high-voltage longwall equipment.
    The second option would also eliminate the need to petition Sec.  
75.804(a) when the cable is designed with a ground-check conductor 
smaller than No. 10 A.W.G. but not smaller than a No. 16 A.W.G.

Section 75.827 Installation and Guarding of Trailing Cables

    Proposed Sec.  75.827 is partially derived from granted PFMs for 
the use of high-voltage continuous mining machines and paragraph (a)(3) 
is new. This section would require that trailing cables be installed 
and guarded according to the specific standards set forth in the 
provision. The purpose of this section is to protect high-voltage 
trailing cables from damage. Cable damage that results in exposed 
energized conductors would be a shock hazard to miners.
(a) Trailing Cable Installation
    Proposed paragraph (a) would require that the trailing cable from 
the power center to locations specified in (a)(1), (2), or (3) be 
either supported on insulators or located in an unused entry. If the 
cable is located in a high seam mine and supported on insulators, it is 
less likely to be damaged by equipment running into or over it. A 
damaged cable may expose energized conductors, and thereby present a 
shock hazard to miners. While supporting the cable on insulators in a 
high seam mine would protect the cable from damage and the miner from 
shock hazards, the same would not be true for a low seam mine. 
Consequently, we are proposing the option of allowing the cable to be 
located in an unused entry to achieve the same protection. Permitting 
the cable to be located in an unused entry would provide flexibility 
for mine operators, while maintaining the same measure of protection 
for miners. Although this option was not in most earlier granted PFMs 
for the use of high-voltage continuous mining machines, the option was 
allowed in recently granted PFMs for use of these machines. We request 
comments on this provision for other methods of installing and 
protecting the high-voltage trailing cable.
    If the cable is located in an unused entry, the proposed rule would 
require that barricade tape and warning signs be used to alert miners 
that high-voltage cables are present. This proposed rule would not 
preclude foot travel but would warn operators of mobile equipment 
against traveling into the entry and running over the cable. An 
acceptable method to comply with both the barricade tape and warning 
sign requirements would be the use of pre-printed tape that displays a 
warning such as ``DANGER HIGH-VOLTAGE CABLE.''
    Proposed paragraph (a)(1) would require the cable to be supported 
on insulators or placed in a barricaded, unused entry from the power 
center to the last open crosscut during advance mining. Proposed 
paragraph (a)(2) would require the cable to be supported on insulators 
or placed in a barricaded, unused entry from the power center to within 
150 feet from any pillar workings during second mining. Second mining 
is defined in existing 30 CFR 75.332(b)(1) as ``intentional retreat 
mining where pillars have been wholly or partially removed, regardless 
of the amount of recovery obtained.'' Proposed paragraph (a)(3) would 
require the cable to be supported on insulators or placed in a 
barricaded, unused entry from the power center to within 150 feet of 
the continuous mining machine when the machine is used in outby areas. 
Examples of continuous mining machine usage in outby areas would 
include, but not be limited to, cutting overcasts, underpasses and 
sumps, and cleaning rock falls.
    A cable extending beyond the locations specified in proposed 
paragraphs (a)(1), (2), and (3) does not have to be supported on 
insulators or placed in an unused entry. Furthermore, we believe that 
supporting the cable beyond the specified locations would be 
impractical because of the dynamics of the mining process. 
Consequently, the provision does not require that the cable be 
supported beyond these locations.
(b) Temporary Storage of Cables
    Proposed paragraph (b) would allow the temporary lacing of cable 
into a sled or crosscut to store the slack cable in those areas 
specified in paragraphs (a)(1) to (a)(3) of this section. Proposed 
paragraph (b) is an exception to proposed paragraph (a) which requires 
that the trailing cable be either supported on insulators or located in 
a barricaded, unused entry. A sled or crosscut would be required to be 
barricaded to prevent mobile equipment from running over the cable in 
those areas specified in paragraphs (a)(1) to (a)(3) of this section. 
Warning signs would also be required to alert miners to the existence 
of an energized, high-voltage cable. Barricade tape pre-printed with a 
warning such as ``DANGER HIGH-VOLTAGE CABLE'' would meet the intent of 
the proposed rule. The temporary storage requirements of this paragraph 
are intended to protect the cable from damage and miners from 
contacting the energized cables.
(c) Guarding
    Proposed paragraph (c)(1) of Sec.  75.827 would require that the 
high-voltage cable be guarded at certain locations. These locations are 
those sections of the cable where miners are likely to come in contact 
with the cable and where the cable may be subject to possible damage. 
All guarding would be required to fully cover the cable in the areas 
specified in (c)(1)(i)-(iii) to provide a physical barrier between the 
cable and the miners. While guarding might cover a damaged cable, the 
damaged cable should be repaired immediately or removed from service as 
required by existing Sec.  75.512. The purpose for requiring guarding 
is to protect the miner from shock hazards and protect

[[Page 42823]]

the cable from damage rather than for the purpose of repairing the 
cable.
    Proposed paragraph (c)(2) would require that guarding be 
constructed from grounded metal or nonconductive flame-resistant 
material. If a marking does not appear on the guarding to indicate that 
it is flame-resistant, we will request documentation to substantiate 
the flame-resistance quality. Metal and non-conductive guarding could 
be either a continuous length or overlapping shorter pieces. Shorter 
pieces of metal guarding would need to be bonded together to ensure a 
continuous metallic path. In addition, metal guarding would have to be 
bonded and grounded.
    Additionally, if the cable becomes damaged so that high-voltage 
conductors become exposed, it can create a shock hazard for miners. If 
grounded metal guarding is used, it would activate the ground-fault 
protection and de-energize the cable. If non-conductive guarding is 
used, it would isolate miners from the exposed, energized conductors. 
Therefore, the use of these materials would help prevent miners from 
being exposed to shock hazards if they contact the guarding when 
energized conductors are exposed.
(d) Suspended Cables and Cable Crossovers
    Proposed paragraph (d)(1) offers a mine operator two options for 
protecting the high-voltage trailing cable in or inby the last open 
crosscut when equipment must cross any portion of the cable. The option 
provided by proposed paragraph (d)(1)(i) would require the high-voltage 
trailing cable to be suspended from the roof in those mines where 
sufficient clearance exists so that mine equipment will not damage the 
cable. The option provided by proposed paragraph (d)(1)(ii) would 
require that the high-voltage trailing cable be protected by a 
commercially available cable crossover. Where sufficient clearance from 
the mine equipment to the mine roof does not exist, a mine operator 
must use the option in proposed paragraph (d)(1)(ii). Cable crossovers 
are commercially available and have been used throughout the industry 
to protect cables from being damaged by equipment. These provisions 
help ensure that the high-voltage trailing cable is protected from 
damage by moving equipment. If possible, work procedures should be 
developed to minimize the need for suspending the cable or using cable 
crossovers.
    Proposed paragraph (d)(2) specifies the minimum design requirements 
for the cable crossovers. These minimum design requirements are 
intended to ensure that mine operators consider both equipment size and 
type in use at their mine so that the equipment is able to cross over 
the cable without damage to the cable. For example, mines that use 
track mounted equipment should use crossovers capable of preventing 
damage to the cable from the equipment track cleats. It has been our 
experience that cable crossovers provide protection to cables when 
properly used.

Section 75.828 Trailing Cable Handling and Pulling

    Proposed Sec.  75.828(a) is derived from granted PFMs for the use 
of high-voltage continuous mining machines. Proposed paragraph (a) 
addresses the types of personal protective equipment required to be 
used when it is necessary to handle energized cables. Proposed Sec.  
75.828(b) is new, and is based on our concern that cable damage may 
result from improper pulling. Paragraph (b) would require de-energizing 
the cable and following the manufacturer's procedures for pulling the 
cable by equipment other than the continuous mining machine.
(a) Handling
    Proposed paragraph (a) of this section would prohibit handling 
energized high-voltage trailing cables without wearing properly tested 
and rated insulating gloves. The provision would require that testing 
and rating of the insulating gloves be in accordance with proposed 
Sec.  75.833. In addition, paragraph (a) would require that if mitts, 
hooks, tongs, slings, aprons, or other personal protective equipment 
are used to handle the energized cable, insulating gloves must also be 
used. This would ensure that miners are protected against shock hazards 
while handling energized cables.
(b) Pulling
    Proposed paragraph (b) of Sec.  75.828 would require that the 
trailing cable be de-energized prior to being pulled by equipment other 
than the mining machine. The proposed paragraph would also require that 
the cable manufacturers' pulling procedures be followed. Cable 
manufacturers' recommendations usually include: The proper application 
of a rope or sling to pull the cable; pulling procedures that will not 
exceed the minimum bending diameter; maximum length of trailing cable 
that can be safely pulled; and the number of corners that it can be 
pulled around.
    The purpose of this requirement would be to prevent damage to the 
cable. For example, when pulling cables with ropes, if a loop smaller 
than the minimum bending diameters for the size of the trailing cables 
being pulled is created, the cable can be damaged. Proper pulling 
procedures would minimize cable damage and protect miners against shock 
hazards.

Section 75.829 Tramming Continuous Mining Machines In and Out of the 
Mine, and From Section to Section

    Proposed Sec.  75.829 is partially derived from granted PFMs for 
the use of high-voltage continuous mining machines, and proposed Sec.  
75.901. High-voltage continuous mining machine PFMs include 
requirements for either using a portable transformer that supplies 995-
volts to the hydraulic pump motor and controls, or a temporary onboard 
step-up transformer to power the 2400-volt hydraulic pump motor and 
controls on the machine. In addition to these two options, the Agency 
has granted petitions to modify Sec.  75.901 to allow the use of low-/
medium-voltage, three-phase, diesel-powered generator sets to move 
section equipment. We anticipate the need to use high-voltage diesel-
generator sets to move high-voltage continuous mining machines.
    In developing this section, we envisioned the use of the following 
power sources to tram the continuous mining machine: a medium-voltage 
power source, an onboard step-up transformer, and a high-voltage diesel 
generator set to energize the hydraulic pump motor and controls of the 
continuous mining machine.
(a) Conditions of Use
    Proposed paragraph (a) of this section sets forth the general 
requirements when using any of the power sources specified in paragraph 
(c) of this section for moving continuous mining machines. Proposed 
paragraph (a)(1) of this section is derived from Sec.  75.500 which 
prohibits equipment not approved by us as ``permissible'' to be taken 
into or used in specific areas of the mine. Typically, these power 
sources are not ``permissible'' and, therefore, must not be permitted 
in these areas.
    Proposed paragraph (a)(2) is new. It would require that the 
continuous mining machine not be used for mining or cutting while being 
trammed from section-to-section or in or out of the mine if the mining 
machine is powered by a medium-voltage power source, an onboard step-up 
transformer, or a high-voltage diesel-generator set. However, if mining 
or cutting is required, a power center that meets the requirements of 
Sec.  75.825 must be used. In granted PFMs, the power sources permitted 
for tramming the continuous mining

[[Page 42824]]

machine included rewiring of the input to use 995 volt for tram and 
control functions, or an onboard step-up transformer. Typically these 
sources do not have the capacity to power the continuous mining machine 
for mining or cutting functions. Proposed paragraphs (c)(1) and (c)(2) 
are identical to the PFM requirements, while proposed paragraph (c)(3) 
permits the use of a high-voltage diesel generator. If mining or 
cutting were attempted while the machine is powered by these power 
sources, overloading and loss of power could occur. Typically these 
power sources are not of sufficient size to power all motors on the 
continuous mining machine for mining or cutting purposes.
    Proposed paragraph (a)(3) would require that low-, medium-, and 
high-voltage cables comply with existing Sec. Sec.  75.600-1, 75.907, 
and proposed Sec.  75.826 when using the power sources specified in 
paragraph (c) of this section for moving continuous mining machines. 
Existing Sec.  75.600-1 requires flame-resistant cables, existing Sec.  
75.907 specifies the design requirements for medium-voltage trailing 
cables, and proposed Sec.  75.826 specifies the design requirements for 
high-voltage trailing cables.
    Proposed paragraph (a)(4) would require that the high-voltage cable 
be secured on-board the mining machine. When using an on-board step-up 
transformer or a diesel-generator set, as permitted in proposed 
paragraphs (c)(2) and (c)(3), respectively, of this section, the 
energized high-voltage cable would need to be secured on-board the 
mining machine. If the trailing cable does not fit on the machine, a 
shorter length of cable should be substituted to connect the diesel-
generator output to the continuous mining machine. The purpose of this 
requirement is to prevent anyone from handling energized, high-voltage 
cables and to minimize cable damage while tramming the continuous 
mining machine.
(b) Testing Prior to Tramming
    Proposed paragraph (b) of Sec.  75.829 is derived from granted PFMs 
to modify Sec.  75.901 to allow the use of low- and medium-voltage 
diesel generators. Proposed paragraph (b)(1) would require that a 
qualified person conduct ground-fault and ground-wire monitor tests on 
the power sources specified in proposed paragraph (c) of this section, 
and that the circuits pass these tests prior to moving the continuous 
mining machine. If these tests indicate equipment failure, paragraph 
(b)(1) would require the mine operator to comply with proposed Sec.  
75.832(f), and correct the defect prior to moving the mining machine. 
Paragraph (b)(1) would also require that the qualified person record 
the results of the tests, and the mine operator maintain a record of 
the tests for one year as required by proposed Sec.  75.832(g). The 
ground-fault test would verify that the circuit will be de-energized 
when a ground-fault condition exists. Power center manufacturers 
provide test circuits so ground-fault protection can be tested without 
subjecting the power system to an actual ground-fault condition. The 
ground-wire monitor test would verify that the circuit will be de-
energized when the ground-check or grounding circuit is opened. Ground-
wire monitor manufacturers provide a built-in test switch for this 
purpose. Ground-wire monitors would be required when low and medium 
power sources are used as permitted by proposed paragraphs (c)(1)(i) 
and (c)(2)(i) of this section. Ground-wire monitors would not be 
required when the provision of this section requires the use of 
external bonding for high-voltage equipment. A ground-wire monitor 
would not be required for high-voltage circuits of power sources 
specified in proposed paragraphs (c)(2) and (c)(3). In these 
applications, external bonding required by proposed Sec. Sec.  
75.829(c)(2)(iii)(B) and 75.829(c)(3)(ii) would be used to connect the 
frames of high-voltage equipment together.
    Proposed paragraph (b)(2) would require that prior to tramming the 
continuous mining machine, a responsible person designated by the 
operator, test the grounded-phase detection circuit on the high-voltage 
continuous mining machine to ensure that the detection circuit would 
detect a grounded-phase condition. This is the same requirement as 
proposed Sec.  75.832(e), except the test needs to be conducted prior 
to tramming. If these tests indicate equipment failure, the mine 
operator must comply with proposed Sec.  75.832(f), and correct the 
defect prior to moving the mining machine.
    Proposed paragraph (b) would not require a repeat of the ground-
fault, ground-wire monitor, and grounded-phase tests when a continuous 
mining machine is stopped intermittently while tramming. The purpose of 
this paragraph is to require that functional tests be performed before 
the equipment begins its move from the surface to underground, from 
underground to the surface, or moves from one part of the mine to 
another. It does not require a functional test after momentary or 
incidental stoppage during the moving process.
    This method of testing enhances safety by preventing miners from 
being exposed to energized circuits while performing the test. The 
combination of the ground-fault, ground-wire monitor, and grounded-
phase tests would ensure safety devices operate to protect miners from 
shock hazards should a fault condition occur.
(c) Power Sources
    Proposed paragraph (c) would specify power sources, in addition to 
the power center, that may be used when the mining machine is moved in 
and out of the mine or from section to section. Power sources specified 
in this section have been selected to avoid the need to handle 
energized, high-voltage cables.
(1) Medium-Voltage Power Source
    Proposed paragraph (c)(1) of Sec.  75.829 is derived from the 
granted PFMs for the use of high-voltage continuous mining machines. 
This option would allow the use of a medium-voltage power source that 
supplies 995 volts to the continuous mining machine. Figure 1 in this 
section illustrates a high-voltage continuous mining machine using a 
995 volt power source. The power source can be supplied by the mine's 
power system, or a low- or medium-voltage diesel-generator set. If the 
power source is a portable transformer, the proposed rule would 
prohibit moving the transformer while energized. However, if a low- or 
medium-voltage diesel-generator set is used as a power source, the rule 
would permit the generator set to be moved while energized. If a diesel 
generator supplies power to a separate portable transformer, the 
proposed rule would prohibit the transformer from being moved while 
energized. To use the option in this paragraph, the machine circuitry 
would need to be rewired to allow the medium-voltage to energize the 
tram and hydraulic pump motor circuits. Backfeeding the continuous 
mining machine power transformer with medium voltage to energize the 
high-voltage circuit would be prohibited. In addition, the mine 
operator would have to comply with the applicable provisions in 
Sec. Sec.  75.500 through 75.1000, such as overcurrent, ground-fault, 
undervoltage, and ground-wire monitors.
(2) Onboard Step-Up Transformer
    Proposed paragraph (c)(2) of Sec.  75.829 is derived from granted 
PFMs for the use of high-voltage continuous mining machines. It would 
allow the use of a temporary onboard step-up transformer. The 
transformer would convert low- or medium-voltage to high-voltage to 
power the continuous mining machine.

[[Page 42825]]

Figure 2 in this section illustrates this configuration. Proposed 
paragraph (c)(2)(i) would require low- or medium-voltage to comply with 
applicable requirements in 30 CFR part 75. For example, overcurrent, 
ground-fault, and undervoltage protection required in Subpart J are 
applicable.
    Proposed paragraph (c)(2)(ii) would require that the high-voltage 
output circuit of the transformer comply with proposed Sec.  75.824. 
For a detailed discussion of these requirements see the section-by-
section discussion to proposed Sec.  75.824.
    Proposed paragraph (c)(2)(iii) would require that the transformer 
be securely installed on-board the continuous mining machine to prevent 
it from falling off the machine and to minimize vibration. Vibration 
could lead to an internal ground-fault or damage to the transformer. 
The frame of the on-board temporary transformer would be required to be 
bonded to the continuous mining machine frame and the metallic shell of 
each cable coupler by at least a No. 1/0 A.W.G. or larger conductor, 
and connected to the incoming ground wire of the trailing cable. This 
would ensure a low impedance grounding path from the onboard 
transformer to the outby power source should a ground-fault occur. 
Paragraph (c)(2)(iii)(C) would require that the transformer be equipped 
with at least two interlock switches for each cover and an external 
emergency stop switch to de-energize outby power when activated.
(3) Diesel-Generator Set
    Proposed paragraph (c)(3) of Sec.  75.829 is new. It contains 
requirements for using a diesel-generator set to supply high-voltage 
power for the continuous mining machine in certain circumstances. The 
first circumstance in which the requirements apply is when moving the 
continuous mining machine from section-to-section or in and out of the 
mine. The second circumstance is when the trailing cable to the 
continuous mining machine is providing high-voltage power from a high-
voltage diesel generator set or a combination of a diesel generator set 
and a transformer.
    A diesel-generator set could be either a high-voltage generator or 
a combination of a low-, medium-, or high-voltage generator and a 
transformer.
    When the trailing cable to the continuous mining machine is 
providing low- or medium voltage from a diesel generator set or a 
combination of a diesel generator set and a transformer, proposed 
paragraph (c)(1) or (c)(2) would apply. If a low- or medium-voltage 
generator is to be used, it would require a PFM of existing Sec.  
75.901, Protection of low- and medium-voltage three-phase circuits used 
underground. Figures 3 and 4 of this section illustrate the variations 
when the trailing cable connected to the continuous mining machine is 
energized with high-voltage from a diesel-generator power source.
    Proposed paragraph (c)(3)(i) would require a grounding resistor to 
satisfy two requirements. First, it would have to be rated for the 
maximum voltage to which it is subjected. Second, it would have to 
limit the ground-fault current to no more than 0.5 ampere. Requiring a 
grounding resistor rated for the maximum voltage would ensure that 
adequate insulating properties are provided for the grounding resistor. 
This is especially important when using autotransformers. When using an 
autotransformer, the grounding resistor would be required to be located 
between the neutral of the wye connected generator and the generator 
frame, and it must be rated for the highest output voltage of the 
autotransformer. A phase-to-ground fault occurring on the secondary 
side of the autotransformer would subject the grounding resistor to the 
output voltage of the autotransformer. This is because autotransformers 
have only one winding-per-phase and do not provide the electrical 
isolation characteristics necessary to create a separately derived 
system. A resistor that is subjected to a voltage higher than its 
rating can potentially explode, causing serious injury or death to 
persons nearby, or it can open from overcurrent, leaving the system 
ungrounded. Limiting the ground-fault current to not more than 0.5 
ampere, and providing the sensitive ground-fault protection set forth 
in paragraphs (c)(3)(iv) provides increased protection against 
explosion, fire, and electrical shock.
    If an isolation transformer is used in conjunction with a high-
voltage generator, another neutral grounding resistor would need to be 
connected between the neutral of the transformer and its frame. This 
provision is intended to limit the voltage on the frame of the 
generator, transformer, and continuous mining machine to prevent a 
shock hazard during ground-faults.
    Proposed paragraph (c)(3)(ii) would require bonding of the non-
current carrying metal parts of the generator, transformer, and all 
cable couplers to the continuous mining machine using at least a No. 1/
0 A.W.G. grounding conductor. This would eliminate any potential 
differences between equipment frames and provide a low impedance path 
for ground-fault current. The external No. 1/0 A.W.G. grounding 
conductor would provide visual evidence of a ground-fault current path 
and offer mechanical strength and durability. The intent of this 
provision is to minimize miners' exposure to shock hazards. This 
provision would satisfy the requirements of existing Sec.  75.803, and 
eliminate the need for a ground-wire monitor.
    Proposed paragraph (c)(3)(iii) would require the generator set to 
be in close proximity to the continuous mining machine. This provision 
would eliminate the hazards associated with handling energized high-
voltage cables discussed in proposed Sec.  75.828. Close proximity is 
intended to mean as close as practical using a solid connecting device 
to prevent free movement. This proposed paragraph would also require 
that the generator set and the continuous mining machine be securely 
attached by means of a tow-bar to prevent the generator set from moving 
freely. Chains, ropes, or slings would not be permitted as a sole means 
of preventing free movement. Compliance with this provision would limit 
the cable length between the generator and the continuous mining 
machine and thereby minimize cable handling and damage.
    Proposed paragraph (c)(3)(iv) would require each three-phase output 
circuit, from the generator and transformer when used, to be equipped 
with sensitive ground-fault protection. The ground-fault circuit would 
be required to consist of a single window (zero sequence) current 
transformer and an instantaneous ground-fault device that would cause 
the appropriate circuit-interrupting device to open and the diesel 
engine to shut down. Ground-fault devices must cause the circuit 
interrupting device to open at no more than 0.125 ampere. Additionally, 
the proposed rule would prohibit the equipment grounding conductor from 
passing through the ground-fault current transformer. Passing the 
equipment grounding conductor through the current transformer would 
prevent detection of any ground-fault current.
    Proposed paragraph (c)(3)(v) would require each three-phase 
circuit, from the generator and transformer when used, to be equipped 
with short-circuit and undervoltage protection. The purpose of short-
circuit and undervoltage protection is discussed under proposed 
Sec. Sec.  75.824(a)(1) and 75.824(a)(3).
    Proposed paragraph (c)(3)(vi) would require a test circuit for each 
ground-fault device. The purpose of a test

[[Page 42826]]

circuit is discussed under proposed Sec.  75.824(a)(2)(vii).
    Proposed paragraph (c)(3)(vii) would require labels to be mounted 
next to or on the instantaneous trip unit of each circuit interrupting 
device. This label would list the maximum circuit interrupting device 
setting allowed for short-circuit protection of the respective circuit. 
Since the minimum short circuit current is calculated using the maximum 
length of cable allowed, the label will assist in ensuring that 
adequate short circuit protection for each circuit is provided. Proper 
short-circuit settings will prevent sustained arcing during electrical 
faults and a subsequent fire hazard from occurring.

Section 75.830 Splicing and Repair of Trailing Cables

(a) Splices and Repairs
    Proposed Sec.  75.830(a) is derived from granted PFMs for high-
voltage continuous mining machines. This proposed section addresses the 
training/qualifications and the manner in which the trailing cable is 
to be spliced to ensure that miners are not exposed to shock and burn 
hazards while splicing or repairing the cable.
    Proposed paragraph (a)(1) would require that cable splicing and 
repair be performed only by a qualified person who received specific 
training in cable splicing and repair of high-voltage cables. This 
training must be accomplished through the annual training under 
75.153(g). The intent of this provision is to ensure that the person 
performing the splicing and repair of cable understands the 
construction of the cable, the purpose of every component, and the 
hazards associated with failure to replace each component with a 
component similar to the original.
    Proposed paragraph (a)(2) would require that the spliced or 
repaired cable provide the same degree of protection to miners as the 
original cable. The quality of workmanship is vital to maintaining the 
same level of protection to miners as provided by the original cable.
    Proposed paragraph (a)(3) would require that splices and repairs of 
trailing cables satisfy the requirements in existing Sec.  75.810. 
Existing Sec.  75.810, among other things, references existing Sec.  
75.604 which requires that the spliced or repaired cable be 
mechanically strong and provide the same flexibility and conductivity 
as the original cable. It also requires that the cable be effectively 
insulated and sealed to exclude moisture. Moisture would minimize the 
insulation quality and could render the splice a potential shock hazard 
to miners. Further, the splice or repair would be required to have 
flame-resistant qualities and good bonding to the outer jacket. The 
trailing cable, which would be required to have shielding around each 
power conductor and a double jacketed protection, must be repaired 
using an MSHA-approved splice kit. These kits provide specific material 
and instructions to be used when splicing or repairing the cable to 
ensure that it is flame resistant. Using this material and following 
these instructions is necessary to ensure the flame-resistant quality 
of the cable, and avoid exposing miners to potential fire and shock 
hazards.
(b) Permanent Cable Repair
    Proposed paragraph (b) is derived from granted PFMs for the use of 
high-voltage continuous mining machines, and would require that MSHA-
approved high-voltage kits be used, which include instructions for 
outer-jacket repairs and splices. Because the outer jacket protects the 
cable from damage, it is important to use appropriate materials and 
follow proper procedures.
    The majority of PFMs included a provision to prohibit the use of 
temporary and/or permanent tape-type splices. The purpose of this 
prohibition was to prevent the use of non-vulcanizing tape from being 
used for splices or outer jacket repair. Regular tape repairs to high-
voltage trailing cables do not exclude moisture which leads to 
insulation degradation and subsequent ground-fault conditions. When the 
materials in the MSHA-approved kits are properly applied, they will 
create a splice or outer jacket repair that will exclude moisture from 
the trailing cable. Since this proposed paragraph requires the use of 
an MSHA-approved high-voltage kit, this prohibition was not required. 
As explained before, improper high-voltage trailing cable repair can 
lead to miners' being exposed to shock and fire hazards.
(c) Splicing Limitations
    Proposed paragraph (c) is derived from granted PFMs for the use of 
high-voltage continuous mining machines, and would prohibit splicing of 
the trailing cable within 35 feet of the continuous mining machine. Our 
experience with low- and medium-voltage equipment has shown that this 
portion of the cable is subjected to the most stresses and strains. If 
this portion of the cable is spliced, electrical connections in the 
splice can weaken and cause cable damage. This can lead to potential 
shock hazards to miners. In addition, this portion of the cable is 
handled by miners more often than the rest of the cable. Therefore, the 
probability of miners being shocked by an inadequate splice within this 
portion of cable would be greater.

Section 75.831 Electrical Work; Troubleshooting and Testing

    Proposed Sec.  75.831 is derived from granted PFMs for the use of 
high-voltage continuous mining machines and existing Sec.  75.820. This 
section would specify safe procedures to be followed when performing 
electrical work, including troubleshooting and testing.
(a) Trailing Cable and Continuous Mining Machine Electrical Work 
Procedures
    Proposed paragraph (a) would require that a qualified person de-
energize the trailing cable circuit and complete one of the lock-out 
and tagging procedures specified in paragraphs (a)(1) or (a)(2) prior 
to performing electrical work on the trailing cable or continuous 
mining machine. De-energization is usually accomplished by opening the 
circuit-interrupting device. The qualified person must follow these 
work procedures to prevent inadvertent re-energization. These 
procedures are important to ensure that miners are not exposed to 
potential shock, fire, or other hazards when performing electrical 
work.
    Proposed paragraphs (a)(1) and (a)(2) of this section would specify 
the options available for lock-out and tagging procedures. Depending on 
the power center design, a disconnecting switch or a cable coupler can 
be used to lock-out and tag the trailing cable. Proposed requirement 
(a)(1) specifies work procedures if a disconnecting switch is used on 
the output circuit of the power center supplying power to the 
continuous mining machine. If a disconnecting switch is used, proposed 
paragraph (a)(1)(i) would require the switch to be opened to provide 
visual evidence that the output is de-energized and grounded. Proposed 
paragraph (a)(1)(i) would also require that the switch be locked in the 
open and grounded position and tagged. This would allow the cable 
coupler plug to remain connected to the power receptacle. Additionally, 
proposed paragraph (a)(1)(ii) would require the plug and receptacle to 
be locked together and tagged. The reason for this requirement is that 
we are concerned that someone may unplug the cable from the locked-out 
circuit and plug it into the spare circuit. When this option is used, a 
grounding receptacle would not be needed because opening the 
disconnecting switch grounds the high-voltage trailing cable.

[[Page 42827]]

    We are aware that some mine operators prefer not to disconnect the 
high-voltage couplers since it may lead to problems when re-energizing 
the circuit. The major problem caused by disconnecting the high-voltage 
couplers is the risk of contaminating the coupler's insulation system. 
Using a disconnecting switch to ground and isolate power from the 
trailing cable and continuous mining machine would eliminate the need 
to remove the cable coupler plug from the receptacle.
    Proposed paragraph (a)(2) would permit using the cable coupler as 
the disconnecting device instead of a disconnecting switch. After power 
has been removed, proposed (a)(2)(i) would require the plug to be 
disconnected from the receptacle and reconnected to a grounding 
receptacle. The grounding receptacle, which is mounted on the power 
center, would cause all cable conductors to be grounded to the power 
center frame. Connecting the plug to the grounding receptacle would 
ensure that no voltage would be present in the cable conductors.
    Proposed paragraph (a)(2)(ii) would require the plug and grounding 
receptacle to be locked together and tagged. Tagging would alert other 
miners that work is being done on the circuit, and the lock would 
prevent the circuit from being re-energized and ungrounded while work 
is being performed. These requirements would prevent shock hazards to 
miners while performing electrical work.
    Lastly, proposed paragraph (a)(2)(iii) would require placing a dust 
cover over the power receptacle to protect it from becoming 
contaminated by dust when the trailing cable is disconnected. Dust is a 
conducting medium and can create ground faults. Another benefit of 
using the dust cover is to prevent contact with parts of the receptacle 
that could be energized.
(b) Trailing Cable Grounding
    Proposed paragraph (b) would require that a qualified person de-
energize the trailing cable circuit as required in paragraph (a) and 
complete one of the lock-out and tagging procedures specified in 
paragraphs (b)(1) or (b)(2) prior to testing and troubleshooting the 
de-energized trailing cable. As discussed in proposed Sec.  75.831(a), 
de-energization is usually accomplished by opening the circuit-
interrupting device. The qualified person must perform these work 
procedures to prevent inadvertent re-energization. These procedures are 
important to ensure that miners are not exposed to potential shock, 
fire, or other hazards when performing electrical work.
    Proposed paragraphs (b)(1) and (b)(2) of Sec.  75.831 would specify 
the lock-out and tagging options available for troubleshooting and 
testing the high-voltage trailing cable. As discussed in proposed 
paragraph (a)(1) of Sec.  75.831, when a disconnecting switch is used, 
it can open and ground the trailing cable circuit. Proposed paragraphs 
(a)(1)(i) and (b)(1)(i) would require the disconnecting switch to also 
be locked and tagged. Proposed paragraph (b)(1)(ii) would require the 
plug to be disconnected from the power receptacle. Proposed paragraph 
(b)(1)(iii) would require that a lock and tag be placed on the plug to 
prevent a miner from inserting the plug into a receptacle. Finally, 
proposed paragraph (b)(1)(iv) would require that a dust cover be placed 
over the power receptacle. These provisions would establish proper work 
procedures prior to testing and troubleshooting of the trailing cable.
    Proposed paragraph (b)(2) addresses the design where a switch is 
not provided. In this case, the cable coupler would be used as the 
disconnecting device instead of a disconnecting switch, to establish 
work procedures when troubleshooting and testing high-voltage trailing 
cables. Proposed paragraphs (a)(2)(i) and (b)(2)(i) of this section 
would require the plug to be disconnected from the power receptacle and 
connected to the grounding receptacle to ensure all power conductors 
are grounded. The plug could then be removed from the grounding 
receptacle. Proposed paragraph (b)(2)(ii) would require the plug to be 
locked and tagged to prevent it from being reconnected to any 
receptacle. Proposed (b)(2)(iii) would require that a dust cover be 
placed over the power receptacle to prevent insulation contamination. 
Troubleshooting and testing of the cable could then commence.
(c) Trailing Cable Troubleshooting
    Proposed paragraph (c) of Sec.  75.831 would allow the trailing 
cable to be ungrounded only for the time necessary to locate a problem. 
Existing Sec.  75.705 requires that all high-voltage lines be de-
energized and grounded before work is performed. This proposed rule 
allows for ungrounding the circuit when troubleshooting and testing. 
Once the problem is found and prior to repair, the work procedures in 
proposed paragraph (a) of this section would have to be followed.
(d) Troubleshooting and Testing Limitations
    Proposed paragraph (d) of this section is derived from granted PFMs 
for the use of high-voltage continuous mining machines and existing 
Sec.  75.820(d), and would require that certain safety procedures be 
followed when troubleshooting and testing low- and medium-voltage 
energized circuits. Only qualified persons wearing properly rated 
gloves would be permitted to perform this work and only for the purpose 
of determining voltages and currents. We recognize that, in some 
instances, it is necessary for circuits or equipment to remain 
energized for troubleshooting and testing. For example, to identify the 
problems within a circuit, it may be necessary to keep the circuit 
energized to take voltage and current readings.
    Proposed paragraph (d)(1) of this section would limit 
troubleshooting and testing of energized circuits only to low- and 
medium voltage systems. Since troubleshooting and testing energized 
circuits is known to be inherently hazardous work, these activities 
would be limited to low- and medium-voltage. This requirement is based 
on lack of availability of equipment that is adequate for testing 
energized high-voltage circuits and equipment. Insulation ratings for 
equipment commonly used to troubleshoot and test energized circuits is 
not adequate for high-voltage circuits.
    Paragraph (d)(2) of this section would permit troubleshooting and 
testing of energized circuits only for the purpose of determining 
voltages and currents. This requirement would also allow 
troubleshooting and testing to evaluate waveform or other electrical 
diagnostic testing.
    Proposed paragraph (d)(3) of this section would require that 
troubleshooting and testing of energized circuits be performed by 
qualified persons who wear protective gloves when the voltage of the 
circuit is 40 volts or more. Based on our electrical accident data and 
experience, 40 volts is the lowest voltage level that is likely to 
cause electrocution. The requirement for a qualified person would 
ensure that the person conducting the testing is aware of the hazards 
associated with these tests. Gloves would be required to provide the 
protection necessary if a miner inadvertently contacted energized 
circuits during troubleshooting and testing. The intent of this 
provision would be to ensure that the tests are conducted in a safe 
manner and miners would not be exposed to shock hazards.
    Dry work gloves, in good condition (free of holes, etc.) would be 
permitted in lieu of rubber insulating gloves on circuits where the 
voltage is 40-volts or more but does not exceed 120 volts nominal, and 
on circuits where the

[[Page 42828]]

voltage exceeded 120 volts nominal but are intrinsically safe. Normally 
the nominal control circuit voltage value is 120 volts for mining 
equipment. Existing Sec.  75.820(d) allows miners to use dry gloves 
when working on intrinsically safe circuits up to 1000 volts.
    Rubber insulating gloves rated for at least the nominal voltage of 
the circuit and equipped with leather protectors would be required to 
be used on circuits where the voltage exceeded 120 volts nominal when 
the circuit is not intrinsically safe. Mining equipment typically has 
ratings such as 220-, 480-, 995-volts and higher. Rubber gloves are not 
commercially rated for each of these voltages. Rubber insulating gloves 
rated at 1,000 volts are commercially available. Therefore, when 
testing or troubleshooting low- and medium-voltage circuits, 1,000 volt 
rated gloves should be used.
(e) Power Center Electrical Work Procedures
    Proposed paragraph (e) is derived from granted PFMs for the use of 
high-voltage continuous mining machines, and existing Sec.  75.820(b). 
Proposed paragraph (e) would specify the safe procedures to be followed 
prior to performing electrical work in the power center. These 
procedures are important to ensure that miners are not exposed to 
potential shock, fire, or other hazards when performing electrical 
work. An exception to these procedures would be when troubleshooting 
and testing low- and medium-voltage circuits.
    Proposed paragraph (e)(1) would require that a qualified person de-
energize affected circuits within the power center prior to performing 
work on the affected circuit. De-energization is usually accomplished 
by opening the appropriate circuit-interrupting device. The qualified 
person must perform these work procedures to prevent inadvertent re-
energization.
    Proposed paragraph (e)(2) would require the corresponding 
disconnecting switch be opened. This switch, if designed and rated as a 
load-break switch, can be used to satisfy (e)(1). If not, then an outby 
circuit interrupting device would need to be opened prior to opening 
the disconnecting switch. Opening the main disconnecting switch would 
de-energize the primary of all transformers supplying high-voltage 
power in the power center and ground the load side circuit of the 
disconnecting switch. Removing high-voltage power and grounding the 
power conductors would protect the person working on a circuit from 
exposure to energized high-voltage circuits, and thereby reduce shock 
and electrocution hazards.
    Proposed paragraph (e)(3) would require that the qualified person 
visually verify that the disconnecting switch contacts are open and 
grounded. This would be accomplished by viewing the position of the 
contacts through a window on the disconnecting switch compartment.
    Proposed paragraph (e)(4) would require that the disconnecting 
switch be locked out and tagged. Proposed paragraph (f) of this section 
contains requirements for using locks. The process of tagging is also 
discussed in detail in proposed paragraph (f) of this section.
    Proposed paragraph (e)(5) would require that all high-voltage 
capacitors in the power center be discharged prior to performing 
electrical work. Because capacitors are energy storage devices, they 
may continue to hold a charge even after the disconnecting switch is 
opened and the circuit is de-energized. Therefore, a grounding stick, 
as proposed in paragraph (h) of Sec.  75.825, would be required to 
discharge these capacitors. This ensures that miners will not be 
exposed to shock hazards.
(f) Lockout and Tagging Responsibilities
    Proposed paragraph (f) is derived from granted PFMs for the use of 
high-voltage continuous mining machines and existing Sec.  75.820(c). 
Proposed paragraph (f)(1) would require each qualified person to 
install a lock and tag on the affected circuit or equipment. 
Additionally, proposed paragraph (f)(1) would require that when one or 
more qualified person(s) is working on the same circuit or equipment, 
each person would have to install their own lock and tag. The proposed 
rule would also require that only persons who install a lock and tag be 
permitted to remove them.
    An individual lock, removable only by the person who installed it, 
places responsibility on the person performing the work and ensures 
personal safety. This requirement is intended to prevent accidental re-
energization of equipment or circuits before all persons have completed 
their work.
    Based on our research, we conclude that proposed paragraph (f)(1) 
would help protect miners against electrocution or electric shock. Our 
research includes a review of the danger and accident history of re-
energization of circuits before work is completed, as well as the 
recommendation to lock-out and tag disconnecting devices prior to 
performing maintenance appearing in both the National Safety Council's 
Data Sheet 237 Revision B, Methods of Locking Out Electrical Switches 
(1971) and the National Fire Protection Association's NFPA 70E 
``Standard for Electrical Safety Requirements for Employee Workplaces'' 
(2000 Edition). This locking system would afford the necessary safety 
protection because persons assigned to place and remove their own locks 
would be more aware of and responsible for their own security, and more 
likely to take the steps necessary to assure proper de-energization. 
This would also reduce the risk of error due to lack of communication 
or inadvertent re-energization.
    Proposed paragraph (f)(2) would allow the mine operator to remove a 
lock and tag under certain conditions. If the person who installed the 
tag is not available (for example if the person is not at the mine or 
is in a remote location in the mine) and the repairs have been 
completed by others, the mine operator can authorize a qualified person 
to remove that person's lock and tag. The mine operator must notify the 
person who originally installed the lock and tag of this action.

Section 75.832 Frequency of Examinations; Recordkeeping

    Proposed Sec.  75.832 is primarily derived from granted PFMs for 
the use of high-voltage continuous mining machines and existing 
Sec. Sec.  75.512 and 75.821(a). The major difference between the 
granted PFMs for the use of high-voltage continuous mining machines and 
this proposed section is that the granted PFMs require some tests to be 
done weekly, whereas this proposed section requires those tests to be 
conducted at least every 7 days. Past experience with existing 
regulations that require weekly examinations and tests revealed 
situations where the actual frequency between examinations and tests 
were as long as 13 days. Changing the requirement to testing every 
seven days would eliminate this long period between tests. To maintain 
a safe workplace, we would require this frequent examination and 
testing of the ground-fault and ground-wire monitor test circuits in 
the power center, the trailing cable, and the high-voltage continuous 
mining machine. Moving this equipment increases the likelihood of 
component failure and break down. Therefore, we consider it important 
that the required examinations and tests be conducted more frequently 
to identify defects. We believe that the examination schedule required 
by this section is necessary to prevent electric shock, fire, ignition, 
and operational hazards to miners.

[[Page 42829]]

    This section would also require that the qualified person verify by 
signature and date that the tests and examinations have been completed. 
Such a record would include any unsafe conditions found and corrective 
actions taken. The section would further require the records be kept 
and made available for at least one year.
(a) Continuous Mining Machine Examination
    Proposed paragraph (a) of Sec.  75.832 would require that a 
qualified person examine the high-voltage continuous mining machine at 
least once every seven days to detect conditions that can expose miners 
to electrical or operational hazards. This paragraph was derived from 
existing Sec. Sec.  75.512 and 75.821. By examining the high-voltage 
continuous mining machine, a qualified person can determine whether the 
electrical protection, equipment grounding, permissibility, cable 
insulation, and control devices are properly installed and maintained. 
The purpose of the examination is to ensure the safety of miners and to 
minimize their exposure to fire, electric shock, ignition, or 
operational hazards.
(b) Ground-Fault Test
    Proposed paragraph (b) would require that at least once every 7 
days, a qualified person would activate the ground-fault test circuit 
to ensure that the simulated ground-fault current would cause the 
circuit-interrupting device to open. In addition, a similar test is 
required by proposed paragraph Sec.  75.829(b)(1) prior to tramming the 
continuous mining machine in or out of the mine or from section to 
section. This paragraph is derived from existing Sec.  75.821 and 
granted PFMs for low- and medium voltage diesel generators. Activating 
the ground-fault test circuit would verify that the ground-fault 
protection operates properly. Existence of a ground-fault can expose 
miners to energized continuous mining machine frames.
(c) Ground-Wire Monitor Test
    Paragraph (c) would require that at least once every 7 days, a 
qualified person test the ground-wire monitor circuit to verify that it 
will cause the corresponding circuit-interrupting device to open if the 
grounding conductor or ground-check conductor is opened. This test, 
like the ground-fault test in paragraph (b) of this section, is 
required by proposed paragraph Sec.  75.829(b)(1) prior to tramming the 
continuous mining machine in or out of the mine or from section to 
section. This paragraph is based on the granted PFMs for the use of 
high-voltage continuous mining machines and granted PFMs for low- and 
medium voltage diesel generators; however, the frequency of testing was 
changed from ``weekly'' to ``at least every 7 days.'' This procedure 
would ensure that ground-wire monitors and corresponding circuit-
interrupting devices will operate properly to de-energize the circuits 
they monitor. Testing of a ground-wire monitor would normally require 
simple activation of a readily available test switch.
(d) Trailing Cable Inspections
    Proposed paragraph (d)(1) and (2) require that the high-voltage 
trailing cable be inspected for damage. The purpose of these provisions 
would be to identify a damaged cable that can expose miners to high-
voltages while handling the cable.
    Proposed paragraph (d)(1) would require a qualified person, once 
each production day, to de-energize the high-voltage trailing cable and 
examine the entire length of the cable from the power center to the 
continuous mining machine. We would consider a production day to be 
when the continuous mining machine is mining coal. The inspection would 
include examining for damage or deterioration of the outer jacket, 
splices, and jacket repairs. In addition, the qualified person would 
need to examine all areas of the cable where guarding is required. 
Although the trailing cable from the power center to the last open 
cross-cut is required to either be supported on insulators or placed in 
an unused entry where miners are not normally working, it is 
periodically handled during the mining cycle. The cable examination 
would not require removal of the guarding. When damaged guarding is 
being replaced, that portion of the cable should be thoroughly 
inspected. Therefore, a qualified person must examine the entire length 
of the cable in a timely manner, thereby protecting miners from shock 
and electrocution hazards. This requirement in the granted PFMs has 
been effective.
    Proposed paragraph (d)(2) would require that at the beginning of 
each production shift a responsible person designated by the operator 
de-energize the high-voltage trailing cable and visually examine the 
portion of the cable that is unsupported. This unsupported portion of 
the cable to be examined would be as follows: From the continuous 
mining machine to the last open crosscut; to within 150 feet of the 
working place during retreat or second mining; or up to 150 feet of the 
continuous mining machine when the machine is used in outby areas for 
cutting overcasts, underpasses, sumps, etc. This unsupported trailing 
cable is more likely to be damaged by mobile equipment and to expose 
miners to shock hazards when handling the cable. Again, the cable 
examination would not require removal of the guarding. Therefore, the 
proposed rule would require that the cable be inspected at the 
beginning of every production shift to ensure the integrity of the 
cable. This proposed requirement is consistent with the provision in 
the granted PFMs for the use of high-voltage continuous mining 
machines.
(e) Grounded-Phase Detection Test
    Proposed paragraph (e) of Sec.  75.832 is derived from the granted 
PFMs for the use of high-voltage continuous mining machines. This 
section would require that at the beginning of each production shift, a 
responsible person designated by the operator, test the grounded-phase 
detection circuit on the high-voltage continuous mining machine to 
ensure that the detection circuit would detect a grounded-phase 
condition. The proposed standard would require that problems which 
arise during normal use of mining equipment be identified and corrected 
so miners would not be exposed to hazards. Testing the grounded-phase 
detection circuit would identify any damage or defects in the detection 
circuit. If the detection circuit is defective, a grounded-phase 
condition can remain undetected and miners could be exposed to shock 
hazards.
(f) Corrective Action
    Proposed paragraph (f) of Sec.  75.832 is derived from existing 
Sec.  75.821(c). Proposed paragraph (f) would require equipment to be 
removed from service or repaired when any examinations or tests reveal 
a potential fire, electric shock, ignition, or operational hazard. This 
provision would assure that equipment that may pose a danger to miners 
is not used until the hazardous condition is corrected. For example, if 
examination of a cable reveals an exposed energized conductor, the 
potential fire, electric shock, and methane gas ignition hazards would 
put the safety of miners at risk and the cable would be required to be 
removed from service or repaired immediately. However, tests or 
examinations may reveal conditions that do not present one of the above 
potential hazards. In this case, the equipment would not need to be 
immediately removed from service, but instead could be repaired in a 
timely manner when material or parts are received. For example, a torn 
portion of guarding material may not present one of the hazards listed 
above.

[[Page 42830]]

Therefore, in that case a mine operator would not have to immediately 
remove the machine from service, but the guarding would have to be 
repaired or replaced in a timely manner.
(g) Record of Tests
    Paragraph (g) of proposed Sec.  75.832 is derived from existing 
Sec.  75.821(d) and is consistent with our other existing recordkeeping 
standards. Proposed paragraph (g) would require that the person who 
examines and tests the equipment under paragraphs (a) to (c) of this 
section, and who is qualified under Sec.  75.153, certify by signature 
and date that the examination and tests have been conducted. We accept 
certification only from the person who examines and tests the equipment 
because the person conducting the test will have knowledge of the 
results of the examinations and tests.
    Another requirement under this proposed paragraph is that the 
qualified person who conducted the examination and tests record any 
unsafe condition found and any corrective action taken.
    Records and certifications of tests and repairs are valuable tools 
for mine operators. Records and certifications can be used to point out 
patterns of equipment failure and design problems. They can also 
provide information that would be useful when investigating accidents.
    Finally, proposed paragraph (g) would require that certifications 
and records be kept for at least 1 year and be made available at the 
mine for inspection by authorized representatives of the Secretary and 
representatives of miners.

Section 75.833 High-Voltage Insulating Gloves Used for Handling High-
Voltage Trailing Cables

    Proposed Sec.  75.833 is derived from granted PFMs for the use of 
high-voltage continuous mining machines. The section addresses the 
ratings, tests required, and frequency of examination and testing of 
high-voltage insulating gloves. The requirements in proposed Sec.  
75.833 would provide miners protection against electric shock hazards 
associated with handling energized high-voltage trailing cables. Like 
the existing PFMs, proposed paragraph (a) of Sec.  75.833 would require 
mine operators to supply high-voltage insulating gloves to miners for 
handling energized high-voltage trailing cables.
    Proposed paragraph (b) of Sec.  75.833 would require high-voltage 
insulating gloves to have a Class 1 (7,500 maximum use volts) or higher 
voltage rating in accordance with ASTM F496-02a, a nationally 
recognized consensus standard that is incorporated by reference. This 
provision is intended to protect miners against electrical shock 
hazards when energized high-voltage cables are handled. In accordance 
with the requirements for incorporating by reference, proposed 
paragraph (b) details how the public may inspect or purchase a copy of 
the incorporated standard and notes that according to his/her statutory 
authorization, the Director of the Federal Register has approved the 
incorporation by reference.
    Proposed paragraph (c) of Sec.  75.833 would require the rubber 
portion of the insulating gloves to be air-tested at the beginning of 
each shift. The test is conducted by rolling the cuff tightly toward 
the palm of the glove in such a manner that air is entrapped inside the 
glove. Puncture detection may be enhanced by listening for escaping air 
or feeling escaping air against the face. We would require that the 
gloves be air-tested to detect damage to the rubber gloves.
    Proposed paragraph (d) of this section would require the leather 
and rubber insulating gloves to be visually examined before each use 
for signs of damage. The purpose of this paragraph would be to detect 
any defect or damage to the glove that may compromise the necessary 
protection to the miner.
    Proposed paragraph (e) of Sec.  75.833 would require the damaged 
rubber gloves to be removed from underground or destroyed. This would 
prevent a miner from using damaged gloves. Use of damaged gloves could 
lead to serious or fatal injuries. The proposed paragraph would also 
require that leather protectors be kept in good condition or replaced. 
If the leather is not kept in good condition, the safety protection 
afforded by the rubber gloves will be compromised.
    Proposed paragraph (f) would require that rubber insulating gloves 
be electrically tested every 30 days in accordance with ASTM F496-02a, 
``Standard Specification for In-Service Care of Insulating Gloves and 
Sleeves,'' that is incorporated by reference as in paragraph (b) of 
this section. The purpose of this formal testing procedure would be to 
ensure that the glove has the proper dielectric strength needed to 
provide proper protection to the miners. While the high-voltage 
longwall rule requires that gloves be tested every six months, we would 
require that the gloves be tested every 30 days because the cable for 
the high-voltage continuous mining machine is handled more frequently. 
The 30 day time period would begin from the first day the glove is 
given to the miner.

Section 75.1002 Installation of Electric Equipment and Conductors; 
Permissibility

    Existing Sec.  75.1002 addresses requirements for conductors and 
cables used in or inby the last open crosscut, and electric equipment 
and conductors and cables used within 150 feet of pillar workings. 
Existing paragraph (b) limits the types of electric conductors and 
cables permitted in areas where permissible equipment is required. This 
paragraph prohibits the installation of conductors such as trolley 
wires and trolley feeder wires, in areas where permissible equipment is 
required, and allows mine operators to use shielded high-voltage 
longwall cables. Permissible equipment is defined under existing Sec.  
18.2, and under Sec.  318(c)(1) of the Mine Act. Such equipment is 
specifically approved by us to minimize the risk of fires and 
explosions in hazardous areas of underground mines.
    Currently, existing Sec.  75.1002 does not allow mines to use high-
voltage continuous miners in or inby the last open crosscut. However, 
high-voltage continuous miners are being used, when approved by us 
through the petition for modification process under Sec.  101(c) of the 
Mine Act. Since 1997, we have granted 38 PFMs to use this equipment. To 
our knowledge, no electrical fatalities have occurred to miners because 
of the use of high-voltage continuous mining machines in accordance 
with the granted high-voltage PFMs. Because of the improved high-
voltage technology, the designed safety benefits and the proven-in-use 
experience, we are proposing to revise existing Sec.  75.1002(b) to 
allow the use of high-voltage continuous mining machines in underground 
coal mines.
    Accordingly, proposed paragraph (b)(5) of Sec.  75.1002 is added to 
modify the existing requirements of Sec.  75.1002 to allow the use of 
shielded high-voltage cables supplying power to permissible continuous 
mining machines. The shielding and design would protect against arcing 
and other electrical ignition hazards that may occur when the outer 
jacket material of the cable is damaged. The use of shielded high-
voltage cables supplying power to continuous mining machines would 
reduce the risk of fire or explosion in face areas since these cables 
have equivalent or superior mechanical and electrical protective 
characteristics. This equipment offers other improved safety features, 
such as sensitive ground-fault protection against shock, fire, and 
explosion hazards. The safety criteria supporting proposed paragraph 
(b)(5) is based on the safe use of high-voltage

[[Page 42831]]

longwalls and high-voltage continuous mining machines.
    The proposed standards would maintain or increase the protection 
currently afforded to miners. They standardize safety provisions 
appearing in only some petitions and add additional protections.

V. Executive Order 12866 (Regulatory Planning and Review and Regulatory 
Flexibility Act)

A. Compliance Costs

    Executive Order (E.O.) 12866 as amended by E.O. 13258 requires that 
regulatory agencies assess both the costs and benefits of intended 
regulations. We have fulfilled this requirement, and have determined 
that this proposed rule would result in estimated yearly net compliance 
cost savings of approximately $1.40 million for mine operators.
    Therefore, this proposed rule is not an economically significant 
regulatory action pursuant to section 3(f)(1) of E.O. 12866.
    For mine operators with 20 to 500 employees, there would be yearly 
compliance costs of about $30,500 and yearly compliance cost savings of 
$1.433 million, which would result in net cost savings of about $1.40 
million. The one mine operator with more than 500 employees who is 
currently using high-voltage continuous mining machines would incur 
yearly compliance costs of $61. For a complete breakdown of the 
compliance costs and savings of the proposed rule see Chapter IV of the 
Preliminary Regulatory Economic Analysis (PREA) associated with this 
rulemaking.

B. Benefits

    The proposed rule would reduce the potential for electrical-related 
fatalities and injuries for several reasons. This risk reduction is 
derived from the improved electrical safety requirements when using 
high-voltage continuous mining machines due to: better design and 
construction criteria (such as required use of double jacketed cables); 
improved ground-fault protection; handling of lighter cables; and 
increased safety requirements for work practices. These design and work 
practice requirements offer greater protection against electrical 
shock, cable overheating, fire hazards, unsafe work and repair 
practices, and back injuries and other sprains caused by handling 
trailing cables. These benefits are detailed in Chapter III of the PREA 
associated with this rulemaking.

C. Regulatory Flexibility Act (RFA) and Small Business Regulatory 
Enforcement Fairness Act (SBREFA)

    The Regulatory Flexibility Act (RFA) requires regulatory agencies 
to consider a rule's economic impact on small entities. Under the RFA, 
we must use the Small Business Administration's (SBA's) criterion for a 
small entity in determining a rule's economic impact unless, after 
consultation with the SBA Office of Advocacy, we establish an 
alternative definition for a small mine operator and publish that 
definition in the Federal Register for notice and comment. For the 
mining industry, SBA defines ``small'' as a mine operator with 500 or 
fewer employees. In addition, we traditionally have considered small 
mine operators to include those with fewer than 20 employees.
    Although the rule does apply to mine operators with fewer than 20 
employees that choose to use high-voltage continuous mining machines, 
our experience has been that no underground coal mine operator with 
fewer than 20 employees has ever requested a PFM to use high-voltage 
continuous mining machines. Therefore, we do not expect mine operators 
having fewer than 20 employees to request PFMs to use high-voltage 
continuous mining machines. However, we have analyzed the economic 
impact of the proposed rule on all underground coal mine operators with 
500 or fewer employees, which conforms to the requirements of the RFA.
1. Factual Basis for Certification
    Using SBA's definition of a small mine operator, the estimated 
yearly net compliance cost savings of the proposed rule on small 
underground coal mine operators is approximately $1.40 million. These 
estimated yearly net compliance cost savings compare with estimated 
annual revenues of approximately $8.3 million for small underground 
coal mine operators with 500 or fewer employees.
    Based on our analysis, we have determined that the proposed rule 
would not have a significant economic impact on a substantial number of 
small underground coal mine operators with 500 or fewer employees. We 
have so certified these findings to the SBA. The factual basis for this 
certification is discussed in Chapter V of the PREA associated with 
this rulemaking.

VI. Paperwork Reduction Act of 1995

    As a result of this proposed rule there would be: (1) an 
elimination of burden hours and related costs approved under OMB 
control numbers 1219-0065 and 1219-0116 (formerly 1219-0067) and (2) 
annual burden hours in the Information Collection Request (ICR) that 
accompanies this rulemaking. The burden hours and related costs for 
these two items are discussed below. However, for a more detailed 
explanation of how the burden hours and related costs for the two items 
were determined, see Chapter VII of the PREA associated with this 
rulemaking.
    The information collection requirements contained in this proposed 
rule have been submitted to the Office of Management and Budget for 
review under 44 U.S.C. Sec. 3504(h) of the Paperwork Reduction Act of 
1995, as amended. Respondents are not required to respond to any 
collection of information unless it displays a current valid OMB 
control number.

Elimination of Burden Hours

    Due to this rulemaking, mine operators would no longer need a PFM 
of existing 30 CFR Sec.  75.1002 to use a high-voltage continuous 
mining machine. Existing OMB control number 1219-0065 includes annual 
burden hours and costs related to the time it takes mine operators to 
prepare and file petitions with us, including PFMs to a high-voltage 
continuous mining machine. As a result of this rulemaking, the burden 
hours and costs approved under OMB control number 1219-0065 that relate 
to the time it takes operators to prepare and file petitions would need 
to be reduced to reflect the fact that PFMs to use a high-voltage 
continuous mining machine would no longer be needed. Therefore, the 
burden hours and costs in OMB control number 1219-0065 should be 
reduced by 84 hours and approximately $4,950, annually.
    In addition, some of the paperwork burden to mine operators in 
proposed Sec.  75.832 are already being accounted for in existing OMB 
control number 1219-0116 (formally OMB 1219-0067). When the high-
voltage continuous miner rule becomes final, the burden in OMB control 
number 1219-0116 will be reduced and accounted for in the ICR that 
accompanies the high-voltage continuous miner rulemaking. Therefore, 
the burden hours and costs in OMB paperwork package 1219-0116 would be 
reduced by 16 hours and approximately $464 annually.

Annual Burden Hours

    The proposed rule would impose 219 annual burden hours and related 
costs of about $6,511 on mine operators. Of the 219 annual burden 
hours, 21 hours and related costs of about $625 are associated with 
conducting a ground-fault and ground-wire monitor circuit

[[Page 42832]]

test prior to tramming the machine under proposed Sec.  75.829, 120 
hours and related costs of about $3,570 are associated with tagging 
requirements under proposed Sec.  75.831, and 78 hours and related 
costs of about $2,320 are associated with a ground-wire monitor circuit 
test under proposed Sec.  75.832(c).
    The following proposed requirements under this rulemaking do not 
have associated paperwork burden hours or costs. Paragraph (i) of 
proposed Sec.  75.825 requires that all compartments providing access 
to energized high-voltage conductors and parts must display a caution 
label to warn miners against entering the compartment(s) before de-
energizing incoming high-voltage circuits. This is a normal business 
practice of manufacturers that make such compartments, as they 
currently place warning labels on the compartments.
    Paragraph (b) of proposed Sec.  75.827 concerns the temporary 
lacing of cables into a sled or crosscut in certain specified areas of 
the mine. In such areas, warning signs and barricade tape must be 
placed around the sled or at the entrances to the crosscut to restrict 
mobile equipment travel. Warning signs and barricade tape that may be 
purchased from any industrial supply vendor may be used to satisfy this 
requirement. The costs for such materials are included in the paperwork 
package that accompanies the proposed rulemaking.
    Paragraphs (a) and (b) of proposed Sec.  75.832 requires that exams 
or tests be conducted at least once every seven days and paragraph (g) 
requires that a record be made of such exams or tests. Paragraph (a) 
requires an exam of the high-voltage continuous mining machine. 
Paragraph (b) requires a test of the ground-fault test circuit. The 
exams of the high-voltage continuous mining machine required by 
paragraphs (a) and (b) are already being conducted as part of a larger 
weekly examination of electrical equipment that is required under 
existing Sec.  75.512 (electrical equipment; examination, testing and 
maintenance). Existing Sec.  75.512 also requires that a record be made 
of all such exams and tests. Thus, the burden associated with exams and 
records under proposed Sec.  75.832(a) and (b) is already accounted for 
under existing Sec.  75.512, and is approved under OMB control number 
1219-0116. Therefore, such burden does not need to be included in the 
ICR accompanying this rulemaking.

VII. Other Regulatory Considerations

The Unfunded Mandates Reform Act

    This proposed rule does not include any Federal mandate that may 
result in increased expenditures by State, local, or tribal 
governments, nor would it increase private sector expenditures by more 
than $100 million annually, nor would it significantly or uniquely 
affect small governments. Accordingly, the Unfunded Mandates Reform Act 
of 1995 requires no further agency action or analysis.

National Environmental Policy Act

    MSHA has reviewed this proposed rule in accordance with the 
requirements of the National Environmental Policy Act (NEPA) of 1969 
(42 U.S.C. 4321 et seq.) the regulations of the Council on 
Environmental Quality (40 U.S.C. part 1500), and the Department of 
Labor's NEPA procedures (29 CFR part 11). Since this proposed rule 
would impact safety, not health, the rule is categorically excluded 
from NEPA requirements because it would have no significant impact on 
the quality of the human environment (29 CFR 11.10(a)(1)). Accordingly, 
MSHA has not conducted an environmental assessment nor provided an 
environmental impact statement.

Assessment of Federal Regulations and Policies on Families

    This proposed rule would have no effect on family well-being or 
stability, marital commitment, parental rights or authority, or income 
or poverty of families and children. Accordingly, Section 654 of the 
Treasury and General Government Appropriations Act of 1999 requires no 
further agency action, analysis, or assessment.

Executive Order 12630: Government Actions and Interference With 
Constitutionally Protected Property Rights

    This proposed rule would not implement a policy with takings 
implications. Accordingly, Executive Order 12630, Governmental Actions 
and Interference With Constitutionally Protected Property Rights, 
requires no further agency action or analysis.

Executive Order 12988: Civil Justice Reform

    This proposed rule was drafted and reviewed in accordance with 
Executive Order 12988, Civil Justice Reform. This proposed rule was 
written to provide a clear legal standard for affected conduct and was 
carefully reviewed to eliminate drafting errors and ambiguities, so as 
to minimize litigation and undue burden on the Federal court system. 
MSHA has determined that this proposed rule would meet the applicable 
standards provided in Section 3 of Executive Order 12988.

Executive Order 13045: Protection of Children From Environmental Health 
Risks and Safety Risks

    This proposed rule would have no adverse impact on children. 
Accordingly, Executive Order 13045, Protection of Children from 
Environmental Health Risks and Safety Risks, requires no further agency 
action or analysis.

Executive Order 13132: Federalism

    This proposed rule would not have ``federalism implications,'' 
because it would not ``have substantial direct effects on the States, 
on the relationship between the national government and the States, or 
on the distribution of power and responsibilities among the various 
levels of government.'' Accordingly, Executive Order 13132, Federalism, 
requires no further agency action or analysis.

Executive Order 13175: Consultation and Coordination With Indian Tribal 
Governments

    This proposed rule would not have ``tribal implications,'' because 
it would not ``have substantial direct effects on one or more Indian 
tribes, on the relationship between the Federal government and Indian 
tribes, or on the distribution of power and responsibilities between 
the Federal government and Indian tribes.'' Accordingly, Executive 
Order 13175, Consultation and Coordination with Indian Tribal 
Governments, requires no further agency action or analysis.

Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    In accordance with Executive Order 13211, MSHA has reviewed this 
proposed rule for its impact on the supply, distribution, and use of 
energy. Because this proposed rule would result in yearly net cost 
savings to the coal mining industry, this proposed rule would neither 
reduce the supply of coal nor increase its price.
    This proposed rule is not a ``significant energy action,'' because 
it would not be ``likely to have a significant adverse effect on the 
supply, distribution, or use of energy'' ``(including a shortfall in 
supply, price increases, and increased use of foreign supplies).'' 
Accordingly, Executive

[[Page 42833]]

Order 13211, Actions Concerning Regulations That Significantly Affect 
Energy Supply, Distribution, or Use, requires no further agency action 
or analysis.

Executive Order 13272: Proper Consideration of Small Entities in Agency 
Rulemaking

    In accordance with Executive Order 13272, MSHA has thoroughly 
reviewed this proposed rule to assess and take appropriate account of 
its potential impact on small businesses, small governmental 
jurisdictions, and small organizations. As discussed in Chapter V of 
this PREA, MSHA has determined and certified that this proposed rule 
would not have a significant economic impact on a substantial number of 
small entities.

List of Subjects

30 CFR Part 18

    Approval regulations, Electric motor-driven mine equipment and 
accessories, Mine safety and health, Reporting and recordkeeping 
requirements.

30 CFR Part 75

    Electric power, Fire prevention, High-voltage continuous mining 
machines, Incorporation by reference, Mandatory safety standards, Mine 
safety and health, Reporting and recordkeeping requirements, 
Underground coal mines.

    Dated: July 6, 2004.
Dave D. Lauriski,
Assistant Secretary of Labor for Mine Safety and Health.

    For the reasons discussed in the preamble, the Mine Safety and 
Health Administration proposes to amend 30 CFR parts 18 and 75 as 
follows:

PART 18--ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES

    1. The authority citation for part 18 continues to read as follows:

    Authority: 30 U.S.C. 957 and 961.

    2. Add Sec.  18.54 to subpart b to read as follows:


Sec.  18.54  High-voltage continuous mining machines.

    (a) Separation of high-voltage components from lower voltage 
components. In each motor-starter enclosure, the high-voltage 
components must be separated from lower voltage components by barriers 
or partitions, or placed in separate compartments to prevent the 
exposure of persons to energized high-voltage conductors or parts. 
Barriers or partitions must be constructed of grounded metal or 
nonconductive insulating board.
    (b) Interlock switches. Each removable cover, barrier, or partition 
of a compartment in the motor-starter enclosure containing high-voltage 
components must be equipped with at least two interlock switches 
arranged to automatically de-energize the high-voltage components 
within that compartment when the cover, barrier or partition is 
removed.
    (c) Circuit-interrupting devices. Circuit-interrupting devices must 
be designed and installed to prevent automatic reclosure.
    (d) Transformers supplying control voltages. (1) Transformers 
supplying control voltages must not exceed 120 volts.
    (2) Transformers with high-voltage primary windings that supply 
control voltages must incorporate a grounded electrostatic (Faraday) 
shield between the primary and secondary windings. Grounding of the 
shield must be as follows:
    (i) Transformers with an external grounding terminal must have the 
shield grounded by a minimum of No. 12 A.W.G. grounding conductor 
extending from the grounding terminal to the equipment ground.
    (ii) Transformers with no external grounding terminal must have the 
shield grounded internally through the transformer frame to the 
equipment ground.
    (e) Onboard ungrounded, three-phase power circuit. A continuous 
mining machine designed with an onboard ungrounded, three-phase power 
circuit must:
    (1) Be equipped with a light that will indicate a grounded-phase 
condition;
    (2) Have the indicator light installed so that it can be observed 
by the operator from any location where the continuous mining machine 
is normally operated; and
    (3) Have a test circuit for the grounded-phase indicator circuit to 
ensure that the circuit is operating properly. The test circuit must be 
designed so that when activated, it does not require removal of any 
electrical enclosure cover or create a double-phase-to-ground fault.
    (f) High-voltage trailing cable(s). High-voltage trailing cable(s) 
must conform to the ampacity and outer dimensions in accordance with 
the Insulated Cable Engineers Association (ICEA) Standard ICEA S-75-
381/National Electrical Manufacturer's Association (NEMA) Standard NEMA 
WC 58-1997. The Director of the Federal Register approves this 
incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51. You may inspect a copy at any of the following locations: MSHA 
Coal Mine Safety and Health District office; the Office of Standards, 
Regulations, and Variances, 1100 Wilson Boulevard, Arlington, VA; or at 
the National Archives and Records Administration (NARA). For more 
information on the availability of this material at NARA, call 202-741-
6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
    You may also purchase a copy from Global Engineering Documents, 15 
Inverness Way East, Englewood, Colorado 80112. In addition, the cable 
must be constructed with:
    (1) 100 percent semi-conductive tape shielding over each insulated 
power conductor;
    (2) A grounded metallic braid shielding over each insulated power 
conductor;
    (3) A ground-check conductor not smaller than a No. 10 A.W.G.; or 
if a center ground-check conductor is used, not smaller than a No. 16 
A.W.G.; and
    (4) Two reinforced layers of jacket; an outer and inner protective 
layer. The inner layer must be a distinctive color from the outer layer 
to allow easy recognition of damaged jacket areas. The color black must 
not be used for either protective layer.
    (g) Safeguards against corona must be provided on all 4,160 voltage 
circuits in explosion-proof enclosures.
    (h) The maximum pressure rise within an explosion-proof enclosure 
containing high-voltage switchgear must be limited to 0.83 times the 
design pressure.
    (i) High-voltage electrical components located in high-voltage 
explosion-proof enclosures must not be coplanar with a single plane 
flame-arresting path.
    (j) Minimum creepage distances. Rigid insulation between high-
voltage terminals (Phase-to-Phase or Phase-to-Ground) must be designed 
with creepage distances in accordance with the following table:

[[Page 42834]]



                                                               Minimum Creepage Distances
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                          Minimum creepage distances (inches) for comparative tracking index (CTI) range
                                                                                                                \1\
         Phase to phase voltage                 Points of  measure       -------------------------------------------------------------------------------
                                                                              CTI >= 500       380 <= CTI < 500    175 <= CTI < 380        CTI < 175
--------------------------------------------------------------------------------------------------------------------------------------------------------
2,400..................................  [Oslash]-[Oslash]..............                1.50                1.95                2.40                2.90
                                         [Oslash]-G.....................                1.00                1.25                1.55                1.85
4,160..................................  [Oslash]-[Oslash]..............                2.40                3.15                3.90                4.65
                                         [Oslash]-G.....................                1.50                1.95                2.40               2.90
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Assumes that all insulation is rated for the applied voltage or higher.

    (k) Minimum free distances. Motor-starter enclosures must be 
designed to establish the minimum free distance (MFD) between the wall 
or cover of the enclosure and uninsulated electrical conductors inside 
the enclosure in accordance with the following table:

                                    High-Voltage Minimum Free Distances (MFD)
----------------------------------------------------------------------------------------------------------------
                                                Steel MFD (in)                       Aluminum MFD (in)
     Wall/cover thickness (in)     -----------------------------------------------------------------------------
                                       A \1\        B \2\        C \3\        A \1\        B \2\        C \3\
----------------------------------------------------------------------------------------------------------------
\1/4\.............................          2.8          4.3          5.8       \4\ NA       \4\ NA       \4\ NA
\3/8\.............................          1.8          2.3          3.9          8.6         12.8         18.1
\1/2\.............................        * 1.2          2.0          2.7          6.5          9.8         13.0
\5/8\.............................        * 0.9          1.5          2.1          5.1          7.7         10.4
\3/4\.............................        * 0.6        * 1.1          1.6          4.1          6.3          8.6
1.................................            *        * 0.6        * 1.0          2.9          4.5         6.2
----------------------------------------------------------------------------------------------------------------
Note *: The minimum electrical clearances must still be maintained in accordance with the minimum clearance
  table of Sec.   18.24.
\1\ Column A specifies the MFD for enclosures that have available three-phase bolted short-circuit currents of
  10,000 amperes rms or less.
\2\ Column B specifies the MFD for enclosures that have a maximum available three-phase bolted short-circuit
  currents greater than 10,000 and less than or equal to 15,000 amperes rms.
\3\ Column C specifies the MFD for enclosures that have a maximum available three-phase bolted short-circuit
  currents greater than 15,000 and less than or equal to 20,000 amperes rms.
\4\ Not Applicable--We do not allow aluminum wall or covers to be \1/4\ inch or less in thickness (See also,
  Sec.   18.31).

    (1) For values not included in the table, the following formulas on 
which the table is based may be used to determine the minimum free 
distance.
    (i) Steel Wall/Cover:
    [GRAPHIC] [TIFF OMITTED] TP16JY04.000
    
    (ii) Aluminum Wall/Cover:
    [GRAPHIC] [TIFF OMITTED] TP16JY04.001
    

Where ``C'' is 1.4 for 2,400 volt systems or 3.0 for 4,160 volt 
systems, ``Isc'' is the three-phase short circuit current in 
amperes of the system, ``t'' is the clearing time in seconds of the 
outby circuit-interrupting device and ``d'' is the thickness in inches 
of the metal wall/cover adjacent to an area of potential arcing.
    (2) The minimum free distance must be increased by 1.5 inches for 
4,160 volt systems and 0.7 inches for 2,400 volt systems when the 
adjacent wall area is the top of the enclosure. If a steel shield is 
mounted in conjunction with an aluminum wall or cover, the thickness of 
the steel shield is used to determine the minimum free distances.
    (l) Static pressure testing of explosion-proof enclosures 
containing high-voltage switchgear. (1) Prototype enclosures. The 
following static pressure test must be performed on each prototype 
design of explosion-proof enclosure(s) containing high-voltage 
switchgear prior to the explosion test(s).
    (i) Test procedure.
    (A) The enclosure must be internally pressurized to at least the 
design pressure, maintaining the pressure for a minimum of 10 seconds.
    (B) Following the pressure hold, the pressure must be removed and 
the pressurizing agent removed from the enclosure.
    (ii) Acceptable performance.
    (A) The enclosure during pressurization must not exhibit--
    (1) Leakage through welds or casting; or
    (2) Rupture of any part that affects the explosion-proof integrity 
of the enclosure.
    (B) The enclosure following removal of the pressurizing agents must 
not exhibit--
    (1) Visible cracks in welds;
    (2) Permanent deformation exceeding 0.040 inches per linear foot; 
or

[[Page 42835]]

    (3) Excessive clearances along flame-arresting paths following 
retightening of fastenings, as necessary.
    (2) Enclosures for production. Every explosion-proof enclosure 
containing high-voltage switchgear manufactured after the prototype was 
tested must undergo one of the following tests or procedures:
    (i) The static pressure test specified in paragraph (l)(1)(i) of 
this section; or
    (ii) An MSHA-accepted quality assurance procedure covering 
inspection of the enclosure.
    (A) The quality assurance procedure must include a detailed check 
of parts against the drawings to determine that--
    (1) The parts and the drawings coincide; and
    (2) The minimum requirements stated in part 18 have been followed 
with respect to materials, dimensions, configuration and workmanship.
    (B) [Reserved]

PART 75--MANDATORY SAFETY STANDARDS--UNDERGROUND COAL MINES

    3. The authority citation for part 75 continues to read as follows:

    Authority: 30 U.S.C. 811.

    4. Add Sec. Sec.  75.823 through 75.833 to subpart I, Underground 
High-Voltage Distribution, to read as follows:


Sec.  75.823  Scope.

    Sections 75.823 through 75.833 of this part are electrical safety 
standards applicable to high-voltage continuous mining machines and 
circuits. A ``qualified person'' within the meaning of these sections 
is a person qualified under Sec.  75.153. Other standards in 30 CFR 
apply to these circuits and equipment where appropriate.


Sec.  75.824  Electrical protection.

    (a) Trailing cable protection. The trailing cable extending to the 
high-voltage continuous mining machine must be provided with short 
circuit, overload, ground-fault, and undervoltage protection by a 
circuit-interrupting device of adequate interrupting capacity and 
voltage as follows:
    (1) Short-circuit protection.
    (i) The current setting must be either the setting specified in 
approval documentation or 75 percent of the minimum available phase-to-
phase short-circuit current, whichever is less; and
    (ii) The time-delay setting must be either the setting specified in 
approval documentation or 0.050 second, whichever is less.
    (2) Ground-fault protection.
    (i) A neutral grounding resistor must limit the ground-fault 
current to no more than 0.5 ampere.
    (ii) A ground-fault device must cause de-energization of the 
circuit extending to the continuous mining machine at not more than 
0.125 ampere. The time-delay of the device must not exceed 0.050 
second.
    (iii) A look-ahead circuit must detect a ground fault condition and 
prevent the circuit-interrupting device from closing as long as the 
ground-fault condition exists.
    (iv) A backup ground-fault device must cause de-energization of the 
circuit extending to the continuous mining machine at not more than 40 
percent of the voltage developed across the neutral grounding resistor 
when a ground fault occurs with the neutral grounding resistor open. 
The time-delay setting of the backup device must not exceed 0.25 
second.
    (v) A thermal device must detect a sustained ground fault current 
in the neutral grounding resistor and must de-energize the incoming 
power. The device must operate at either 50 percent of the maximum 
temperature rise of the neutral grounding resistor or 302[deg] F 
(150[deg] C), whichever is less. Thermal protection must not be 
dependent upon control power and may consist of a current transformer 
and overcurrent relay in the neutral grounding resistor circuit.
    (vi) A single window-type current transformer that encircles all 
three-phase conductors must be used to activate the ground-fault device 
specified in paragraph (a)(2)(ii) of this section. The equipment 
grounding conductor(s) must not pass through the ground-fault current 
transformer.
    (vii) A test circuit for the ground-fault device specified in 
paragraph (a)(2)(ii) of this section must be provided. The test circuit 
must inject no more than 50 percent of the current rating of the 
neutral grounding resistor through the current transformer. When the 
test circuit is activated, the circuit-interrupting device must open.
    (3) Undervoltage protection. The undervoltage device must operate 
on a loss of voltage, de-energize the circuit, and prevent the 
equipment from automatically restarting.
    (b) Reclosing. Circuit-interrupting devices must not reclose 
automatically.
    (c) Onboard Power Circuits. When a grounded-phase indicator light 
on a high-voltage continuous mining machine indicates a grounded-phase 
fault, the following procedures must be implemented:
    (1) The continuous mining machine must be moved immediately to a 
location with a properly supported roof; and
    (2) The grounded-phase must be located and corrected prior to 
placing the continuous mining machine back into operation.


Sec.  75.825  Power centers.

    (a) Main disconnecting switch. The power center supplying high 
voltage power to the continuous mining machine must be equipped with a 
main disconnecting switch that, when in the open position, de-energizes 
the input to all power transformers.
    (b) Trailing cable disconnecting devices. In addition to the 
requirements of paragraph (a) of this section, the power center must be 
equipped with a disconnecting device for each circuit that can supply 
power to the high-voltage continuous mining machine.
    (c) Disconnecting switches. Each disconnecting switch required in 
paragraphs (a) and (b) of this section must be designed, installed, and 
perform as follows:
    (1) Rated for the maximum phase-to-phase voltage of the circuit;
    (2) Rated for the full-load current of the circuit that is supplied 
power through the device.
    (3) Visual observation can be performed to see that the contacts 
are open without removing any covers;
    (4) Grounds all power conductors on the load side when the device 
is in the ``open and grounded'' position;
    (5) Can only be locked in the ``open and grounded'' position;
    (6) Safely interrupts the full-load current of the circuit or 
designed to cause the current to be interrupted automatically prior to 
opening the disconnecting switch; and
    (7) Labeled to clearly identify the circuit it disconnects.
    (d) Barriers and covers. All compartments that provide access to 
high-voltage conductors or parts, must have barriers and covers to 
prevent miners from contacting energized high-voltage conductors or 
parts.
    (e) Main disconnecting switch and control circuit interlocking. The 
power center control circuit must be interlocked with the main 
disconnecting switch in the power center so that:
    (1) When the main disconnecting switch is in the ``open'' position, 
the control circuit can only be powered through an auxiliary switch in 
the ``test'' position; and
    (2) When the main disconnecting switch is in the ``closed'' 
position, the control circuit can only be powered through an auxiliary 
switch in the ``normal'' position.
    (f) Interlocks. Each cover or removable barrier providing access to 
high-voltage

[[Page 42836]]

conductors or parts must be equipped with at least two interlock 
switches. Removal of any of these covers or barriers exposing energized 
high-voltage conductors or parts must cause the interlock switches to 
automatically de-energize the incoming high-voltage to the power 
center.
    (g) Emergency stop switch. The power center must be equipped with 
an externally accessible emergency stop switch hard-wired into the 
incoming ground-wire monitor circuit that de-energizes the incoming 
high-voltage in the event of an emergency.
    (h) Grounding stick. The power center must be equipped with a 
grounding stick to discharge the high-voltage capacitors and circuits. 
The power center must have a label readily identifying the location of 
the grounding stick. The grounding stick must be stored in a dry 
location.
    (i) Caution labels. All compartments providing access to energized 
high-voltage conductors and parts must display a caution label to warn 
miners against entering the compartment(s) before de-energizing 
incoming high-voltage circuits.


Sec.  75.826  High-voltage trailing cables.

    High-voltage trailing cables must--
    (a) Comply with Sec.  18.35 and Sec.  18.54 of this title; and
    (b) Meet either the requirements of Sec.  75.804 or be a type SHD 
cable with a center ground-check conductor not smaller than a No. 16 
A.W.G. stranded conductor.


Sec.  75.827  Installation and guarding of trailing cables.

    (a) Trailing cable installation. The portion of the high-voltage 
cable from the power center to the following locations must be either 
supported on insulators, or located in an unused entry that is provided 
with barricade tape and warning signs to warn mobile equipment 
operators against traveling into the entry:
    (1) To the last open crosscut during advance mining;
    (2) To 150 feet outby any pillar workings during second mining; or
    (3) To 150 feet of the continuous mining machine when the machine 
is used in outby areas or trammed in or out of the mine or from section 
to section.
    (b) Temporary storage of cables. Temporary lacing of the cable into 
a sled or crosscut in areas specified in paragraphs (a)(1) to (a)(3) of 
this section is permitted. Warning signs and barricade tape must be 
placed around the sled or at the entrances to the crosscut to restrict 
mobile equipment travel.
    (c) Guarding. (1) The high-voltage cable must be guarded in the 
following locations:
    (i) Between the power center and the first cable insulator, if 
supported, or between the power center and where the cable enters into 
the unused entry;
    (ii) From the entrance gland for a minimum distance of 10 feet 
outby the last strain clamp on the continuous mining machine; and,
    (iii) At any location where the cable may be damaged by moving 
equipment.
    (2) Guarding must be constructed using nonconductive flame-
resistant material or grounded metal.
    (d) Suspended cables and cable crossovers. (1) When equipment must 
cross any portion of the high-voltage trailing cable in or inby the 
last open crosscut, the cable must be protected from damage by either:
    (i) Suspending it from the mine roof; or
    (ii) Protecting it by using a commercially available cable 
crossover.
    (2) The crossover must have the following specifications:
    (i) A minimum length of 33 inches;
    (ii) A minimum width of 17 inches;
    (iii) A minimum height of 3 inches;
    (iv) A minimum cable placement area of two and one half-inches (2 
\1/2\'') high by four and one-quarter inches (4 \1/4\'') wide;
    (v) Made of nonconductive material;
    (vi) Made of material with a distinctive color. The color black 
must not be used; and
    (vii) Made of material that has a minimum compressive strength of 
6,400 pounds per square inch (psi).


Sec.  75.828  Trailing cable handling and pulling.

    (a) Handling. Miners must not handle the energized trailing cable 
unless they are wearing properly tested and rated insulating gloves as 
specified in Sec.  75.833. If mitts, hooks, tongs, slings, aprons, or 
other personal protective equipment are used to handle energized 
cables, high-voltage insulating gloves must be used in conjunction to 
provide protection against shock hazards.
    (b) Pulling. The trailing cable must be de-energized prior to being 
pulled by any equipment other than the continuous mining machine. Cable 
manufacturers' recommended pulling procedures must be followed when 
pulling the trailing cable with such equipment.


Sec.  75.829  Tramming continuous mining machines in and out of the 
mine, and from section to section.

    (a) Conditions of use. When tramming the continuous mining machine 
in and out of the mine, and from section to section, the following 
requirements apply:
    (1) The power source must not be located in areas where permissible 
equipment is required;
    (2) The continuous mining machine must not be used for mining or 
cutting purposes. This provision applies when using power sources 
specified in paragraphs (c)(1), (c)(2), and (c)(3) of this section;
    (3) Low-, medium-, and high-voltage cables must comply with 
Sec. Sec.  75.600-1, 75.907, and 75.826, respectively; and
    (4) The energized high-voltage cable must be mechanically secured 
on-board the continuous mining machine. This provision applies only 
when using power sources specified in paragraphs (c)(2) and (c)(3) of 
this section.
    (b) Testing prior to tramming. Prior to tramming the continuous 
mining machine--
    (1) A qualified person must activate the ground-fault and ground-
wire monitor test circuits of the power sources specified in paragraph 
(c) of this section to ensure that they pass a functional test. 
Corrective actions and recordkeeping resulting from these tests must be 
in accordance with Sec.  75.832(f) and (g), respectively.
    (2) Where applicable, a responsible person must activate the test 
circuit for the grounded-phase detection circuit on the continuous 
mining machine to ensure that the detection circuit is functioning 
properly. Corrective actions resulting from this test must be in 
accordance with Sec.  75.832(f).
    (c) Power sources. In addition to the power center specified in 
Sec.  75.825, the following are acceptable power sources that may be 
used to tram the continuous mining machine.
    (1) Medium-voltage power source. A medium-voltage power source that 
supplies 995 volts through a trailing cable (See Figure 1 of this 
section). The medium-voltage power source must--
    (i) Not be used to back-feed the high-voltage circuits of the 
continuous mining machine;
    (ii) Comply with all applicable requirements for medium-voltage 
circuits in 30 CFR part 75; and
    (iii) Not be moved when energized if the power source is a portable 
transformer.

[[Page 42837]]

[GRAPHIC] [TIFF OMITTED] TP16JY04.002

    (2) Onboard step-up transformer. A temporary transformer that steps 
up the low- or medium-voltage to high voltage (See Figure 2 in this 
section). The temporary transformer must comply with the following:
    (i) The input trailing cable supplying either low- or medium-
voltage to the step-up transformer must comply with the applicable 
sections of 30 CFR part 75;
    (ii) The high-voltage circuit supplying power to the continuous 
mining machine must comply with Sec.  75.824.
    (iii) The step-up transformer enclosure must be--
    (A) Securely mounted on-board the continuous mining machine and 
installed to minimize vibration;
    (B) Grounded using all of the following methods:
    (1) Connected to the incoming ground wire of the low- or medium-
voltage trailing cable.
    (2) Bonded by a No. 1/0 A.W.G. or larger external grounding 
conductor to the continuous mining machine frame.
    (3) Bonded by a No. 1/0 A.W.G. or larger external grounding 
conductor to the metallic shell of cable couplers; and
    (C) Equipped with at least two interlock switches on every 
removable cover and an externally accessible emergency stop switch to 
remove input power.
[GRAPHIC] [TIFF OMITTED] TP16JY04.003

    (3) Diesel-generator set. A high-voltage diesel-generator set (See 
Figures 3 or 4 in this section) must comply with the following:
    (i) Contain a neutral grounding resistor(s) rated for the maximum 
voltage created when ground-fault conditions occur and to limit the 
ground-fault current to no more than 0.5 ampere. Neutral grounding 
resistor(s) must be located:
    (A) Between the wye connected generator neutral and the generator 
frame; and
    (B) Between the wye connected transformer secondary and the 
transformer frame, when a transformer is used.
    (ii) Have a No. 1/0 A.W.G. or larger external grounding conductor 
to ground the continuous mining machine frame to the following:
    (A) The frame of the generator;
    (B) The frame of the transformer, when used; and
    (C) The metallic shell of each cable coupler.
    (iii) Be connected by a tow-bar and in close proximity to the 
continuous mining machine to prevent free movement of the generator 
set;
    (iv) Have each three-phase output circuit equipped with a device 
with no intentional time-delay that causes the circuit breaker to trip 
and to shut-down the diesel engine when a phase-to-frame fault of 0.125 
ampere or greater occurs. The ground-fault protection must use a single 
window-type current transformer that encircles all three phase-
conductors. The equipment grounding conductor(s) must not pass through 
the ground-fault current transformer.
    (v) Have each three-phase output circuit provided with short-
circuit and undervoltage protection, in accordance with Sec. Sec.  
75.824(a)(1) and 75.824(a)(3), respectively.
    (vi) Have a test circuit for the ground-fault device specified in 
paragraph (c)(3)(v) of this section that injects no more than 50 
percent of the current rating of the neutral grounding resistor through 
the current transformer. When the test circuit is activated, the 
circuit-interrupting device must open.
    (vii) Have a legible label(s) placed on each instantaneous trip 
unit or near each circuit interrupting device showing the maximum 
circuit interrupting device setting(s).

[[Page 42838]]

[GRAPHIC] [TIFF OMITTED] TP16JY04.004

Sec.  75.830  Splicing and repair of trailing cables.

    (a) Splices and repairs. Splices and repairs to high-voltage 
trailing cables must comply with the following:
    (1) Be made only by a qualified person trained in the proper 
methods of splicing and repairing high-voltage trailing cables;
    (2) Be made in a workman-like manner; and
    (3) Be made in accordance with Sec.  75.810.
    (b) Permanent cable repair. Only MSHA-approved high-voltage kits 
which include instructions for outer-jacket repairs and splices are 
acceptable for permanent cable repair.
    (c) Splicing limitations. Splicing of the high-voltage trailing 
cable within 35 feet of the continuous mining machine is prohibited.


Sec.  75.831  Electrical work; troubleshooting and testing.

    (a) Trailing cable and continuous mining machine electrical work 
procedures. Prior to performing electrical work on a high-voltage cable 
or the continuous mining machine, a qualified person must de-energize 
the power center circuit and comply with paragraph (a)(1) or (2) of 
this section:
    (1) If a trailing cable disconnecting switch is provided:
    (i) Open, lock, and tag the disconnecting switch; and
    (ii) Lock and tag the plug to the power receptacle.
    (2) If a trailing cable disconnecting switch is not provided and a 
cable coupler is used as a disconnecting device:
    (i) Remove the plug from the power receptacle and connect it to the 
grounding receptacle;
    (ii) Lock and tag the plug to the grounding receptacle; and
    (iii) Place a dust cover over the power receptacle.
    (b) Trailing cable grounding. Prior to testing and troubleshooting 
trailing cables, a qualified person must de-energize the trailing cable 
circuit as required in paragraph (a) of this section, and comply with 
either of the following work procedures:
    (1) If a trailing cable disconnecting switch is provided:
    (i) Open, lock, and tag the disconnecting switch;
    (ii) Disconnect the plug from the power receptacle;
    (iii) Lock and tag the plug; and
    (iv) Place a dust cover over the power receptacle.
    (2) If a trailing cable disconnecting switch is not provided and a 
cable coupler is used as a disconnecting device:
    (i) Remove the plug from the power receptacle and connect it to the 
grounding receptacle;
    (ii) Remove the plug from the grounding receptacle, then install a 
lock and tag to the plug; and
    (iii) Place a dust cover over the power receptacle.
    (c) Trailing cable troubleshooting. During troubleshooting and 
testing, the de-energized high-voltage cable may be ungrounded only for 
that period of time necessary to locate the defective condition. 
Electrical work or repairs to the trailing cable must be made in 
accordance with paragraph (a) of this section.
    (d) Troubleshooting and testing limitations. Before troubleshooting 
or testing a low- or medium-voltage circuit contained in an enclosure 
with exposed high-voltage conductors or parts, the high-voltage circuit 
must be de-energized, grounded, locked-out, and tagged in accordance 
with paragraphs (a) and (e) of this section, whichever is applicable. 
Troubleshooting and testing energized circuits must be performed only--
    (1) On low- and medium-voltage circuits;
    (2) When the purpose of troubleshooting and testing is to determine 
voltages and currents; and

[[Page 42839]]

    (3) By qualified persons who wear protective gloves on circuits 
that exceed 40 volts in accordance with the following table:

------------------------------------------------------------------------
            Circuit voltage                   Type of glove required
------------------------------------------------------------------------
(i) Greater than 120 volts (nominal)     Rubber insulating gloves with
 (not intrinsically safe).                leather protectors.
(ii) 40 volts to 120 volts (nominal)     Either rubber insulating gloves
 (both intrinsically safe and non-        with leather protectors or dry
 intrinsically safe).                     work gloves.
(iii) Greater than 120 volts (nominal)   Either rubber insulating gloves
 (intrinsically safe).                    with leather protectors or dry
                                          work gloves.
------------------------------------------------------------------------

    (e) Power center electrical work procedures. Before any work is 
performed inside any compartment of the power center, except for 
troubleshooting and testing energized circuits as provided for in 
paragraph (d) of this section, a qualified person must--
    (1) De-energize the affected circuit;
    (2) Open the corresponding disconnecting switch to ensure the 
circuit is isolated;
    (3) Visually verify that the contacts of the disconnecting switch 
are open and grounded;
    (4) Lockout and tag the disconnecting switch with a lock; and
    (5) Discharge all high-voltage capacitors.
    (f) Lockout and tagging responsibilities. (1) When one or more 
qualified person(s) is performing work specified in this section, each 
person must install an individual lock. Locks and tags must be removed 
only by the persons who installed them.
    (2) If the person who installed the lock and tag is unavailable, 
the lock and tag may be removed by a person authorized by the operator, 
provided--
    (i) The authorized person is a qualified person; and
    (ii) The mine operator ensures that the person who installed the 
lock and tag is aware that the lock has been removed.


Sec.  75.832  Frequency of examinations; recordkeeping.

    (a) Continuous mining machine examination. At least once every 7 
days, a qualified person must examine high-voltage continuous mining 
machines to determine that electrical protection, equipment grounding, 
permissibility, cable insulation, and control devices are properly 
installed and maintained.
    (b) Ground-fault test. At least once every 7 days, and prior to 
tramming the high-voltage continuous mining machine, a qualified person 
must activate the ground-fault test circuit required in Sec.  
75.824(a)(2)(vii) and in Sec.  75.829(b)(1) to verify that it will 
cause the corresponding circuit-interrupting device to open.
    (c) Ground-wire monitor test. At least once every 7 days, and prior 
to tramming the high-voltage continuous mining machine, a qualified 
person must examine and test each high-voltage continuous mining 
machine ground-wire monitor circuit to verify that it will cause the 
corresponding circuit-interrupting device to open.
    (d) Trailing cable inspections. (1) Once each production day, a 
qualified person must de-energize and inspect the entire length of the 
high-voltage trailing cable from the power center to the continuous 
mining machine. The inspection must include the outer jacket repairs, 
all splices, and areas where guarding is required.
    (2) At the beginning of each production shift, a responsible person 
designated by the mine operator must de-energize the high-voltage 
trailing cable and visually inspect for damage to the outer jacket, 
from the continuous mining machine to the following locations:
    (i) The last open crosscut;
    (ii) Within 150 feet of the working place during retreat or second 
mining; or
    (iii) Up to 150 feet of the continuous mining machine when the 
machine is used in outby areas.
    (e) Grounded-phase detection test. When a grounded-phase test 
circuit is provided on a high-voltage continuous mining machine, a 
responsible person designated by the mine operator must activate the 
test circuit at the beginning of each production shift to ensure that 
the detection circuit is functioning properly.
    (f) Corrective action. When examinations or tests of equipment 
reveal a potential fire, electrical shock, ignition, or operational 
hazard, the equipment must be immediately removed from service or 
repaired.
    (g) Record of tests. At the completion of examinations and tests 
required under paragraphs (a), (b), and (c) of this section, the person 
conducting such examinations and tests must certify by signature and 
date that they have been conducted. Also, a record must be made of any 
unsafe condition found when conducting the examinations and tests under 
paragraphs (a), (b), and (c) of this section and any corrective action 
taken. Certifications and records must be kept for at least 1 year, and 
must be made available for inspection by authorized representatives of 
the Secretary and representatives of miners.


Sec.  75.833  High-voltage insulating gloves used for handling high-
voltage trailing cables.

    (a) Each mine operator must make high-voltage insulating gloves 
available to miners handling energized high-voltage trailing cables.
    (b) High-voltage insulating gloves must have a voltage rating of at 
least Class 1 (7,500 volts) that meets or exceeds ASTM F496-02a, 
``Standard Specification for In-Service Care of Insulating Gloves and 
Sleeves'' (2002). The Director of the Federal Register approves this 
incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51. You may inspect a copy at any of the following locations: MSHA 
Coal Mine Safety and Health District office; at the Office of 
Standards, Regulations, and Variances, 1100 Wilson Boulevard, 
Arlington, VA; or at the National Archives and Records Administration 
(NARA). For more information on the availability of this material at 
NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. You may 
also purchase a copy from the American Society for Testing and 
Materials, 100 Barr Harbor Drive, West Conshohocken, Pennsylvania 
19428-2959.
    (c) The rubber glove portion of the high-voltage glove must be air-
tested at the beginning of each shift to ensure its effectiveness.
    (d) Both the leather protector and rubber insulating gloves must be 
visually examined before each use for signs of damage or defects.
    (e) Damaged rubber gloves must be removed from the underground area 
of the mine or destroyed. Leather protectors must be maintained in good 
condition or replaced.
    (f) The high-voltage insulating gloves must be electrically tested 
every 30 days in accordance with publication ASTM F496-02a, ``Standard 
Specification for In-Service Care of Insulating Gloves and

[[Page 42840]]

Sleeves'' (2002), as incorporated by reference in paragraph (b) of this 
section.
    5. Add Sec.  75.1002(b)(5) to read as follows:


Sec.  75.1002  Installation of electric equipment and conductors; 
permissibility.

* * * * *
    (b) * * *
    (5) Shielded high-voltage cables supplying power to permissible 
continuous mining machines.

[FR Doc. 04-15841 Filed 7-15-04; 8:45 am]
BILLING CODE 4510-43-P