[Federal Register Volume 67, Number 47 (Monday, March 11, 2002)]
[Rules and Regulations]
[Pages 10972-11005]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-4863]



[[Page 10971]]

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Part II





Department of Labor





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Mine Safety and Health Administration



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30 CFR Parts 18 and 75



Electric Motor-Driven Mine Equipment and Accessories and High-Voltage 
Longwall Equipment Standards for Underground Coal Mines; Final Rule

  Federal Register / Vol. 67, No. 47 / Monday, March 11, 2002 / Rules 
and Regulations  

[[Page 10972]]


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DEPARTMENT OF LABOR

Mine Safety and Health Administration

30 CFR Parts 18 and 75

RIN 1219-AA75


Electric Motor-Driven Mine Equipment and Accessories and High-
Voltage Longwall Equipment Standards for Underground Coal Mines

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

ACTION: Final rule.

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SUMMARY: This final rule establishes MSHA's new mandatory electrical 
safety standards for the installation, use, and maintenance of high-
voltage longwall mining systems used in underground coal mines. The 
final rule also includes design approval requirements for high-voltage 
equipment operated in longwall face areas of underground mines. These 
provisions allow the use of high-voltage longwall face equipment with 
enhanced safety protection from fire, explosion, and shock hazards. In 
addition to providing a safer mining environment and facilitating the 
use of advanced equipment designs, the final rule reduces paperwork 
requirements by eliminating the need for petitions for modification 
(variances).

DATES: This regulation is effective May 10, 2002. The incorporation by 
reference of certain publications listed in the rule is approved by the 
Director of the Federal Register May 10, 2002.

FOR FURTHER INFORMATION CONTACT: Marvin W. Nichols, Jr., Director, 
Office of Standards, Regulations and Variances, MSHA, 4015 Wilson 
Boulevard, Arlington, Virginia 22203-1984. Mr. Nichols can be reached 
at [email protected] (Internet 
e-mail), 703--235-1910 (voice), or 703-235-5551 (fax). You may obtain 
copies of the final rule in alternative formats by calling this number. 
The alternative formats available are either a large print version of 
the final rule or the final rule in an electronic file on computer 
disk. The final rule also is available on the Internet at http://www.msha.gov/REGSINFO.HTM.

SUPPLEMENTARY INFORMATION:

I. Background

    On December 4, 1989, the Mine Safety and Health Administration 
(MSHA) published a proposed rule (54 FR 50062) to revise its electrical 
safety standards for underground coal mines. That proposed rule 
addressed all of the Agency's electrical standards for underground coal 
mines and allowed the use of high-voltage longwall equipment. However, 
it did not specifically focus on the safety issues related to the use 
of high-voltage longwall equipment. The Agency published a new proposed 
rule (57 FR 39036) on August 27, 1992, related specifically to the safe 
use of high-voltage longwall equipment in underground coal mines. These 
rules also specifically addressed approval requirements for high-
voltage electrical equipment operated in longwall face areas of 
underground coal mines. The comment period on the proposed rule was 
scheduled to close on October 23, 1992, but was extended to November 
13, 1992 (57 FR 48350). On October 18, 1995, (60 FR 53891), MSHA 
reopened the rulemaking record for additional comments to the proposed 
rule to provide all interested parties an opportunity to submit 
additional comments. The comment period was scheduled to close on 
November 14, 1995, but was extended to December 18, 1995 (60 FR 57203). 
The Agency received no requests for a public hearing on the proposed 
rule. The record was reopened December 28, 1999, for comments on the 
updated Preliminary Regulatory Impact Analysis (PRIA). The record 
closed February 28, 2000. Only one comment was received. The commenter 
agreed with our economic analysis of the cost impact of the proposed 
rule.
    These revised standards allow the use of high-voltage longwall 
mining systems. Longwall mining methods have undergone numerous 
advances in technology during the past 25 years. These technological 
advances have led to improved and safer systems. The additional 
requirements under 30 CFR part 18 provide enhanced safety protections 
that are consistent with advances in mine technology that allows high-
voltage switchgear to be used on face equipment. Title 30 CFR parts 18 
and 75 of this final rule implements a number of changes to approval 
and safety requirements for high-voltage equipment to accommodate the 
advances in technology in a manner that protects the safety of miners.

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

    Electrical equipment horsepower in mines has increased over the 
years. The voltages required to operate this equipment have also 
increased to accommodate the design of practical and efficient 
equipment. The design of safe, efficient, and practical high-voltage 
electric equipment has improved dramatically in recent years. Because 
of the industry's need for higher voltages and the marked improvement 
in the design and manufacturing technology of high-voltage components, 
MSHA developed rules that establish requirements for safe high-voltage 
electric equipment use. This rule provides improved design requirements 
for longwall equipment, consistent with existing requirements in 30 CFR 
part 18, and contains provisions that accommodate new design 
technology, are practical, and lessen burdens on the mining community, 
while preserving safety and health protections for miners.
    The safety criteria supporting the rule are based on research 
conducted over the past 18 years by the former U.S. Bureau of Mines 
(USBM) and MSHA. USBM functions are now a part of the National 
Institute of Occupational Safety and Health. This research included the 
following: (1) Foster-Miller research, under USBM contract No. 
H0308093, which developed a recommended high-voltage permissible 
loadcenter criteria; (2) MSHA research, under USBM contract No. 
J0333909, which resulted in modified criteria to address high-voltage 
permissible switchgear enclosures and the development of test 
facilities for acceptance of high-voltage permissible loadcenters and 
switchgear enclosures; (3) Follow-up MSHA inspections on high-voltage 
machines and longwall mining systems operating under experimental 
permits to confirm design requirements and operational safety; (4) MSHA 
internal research and review of engineering reports for further 
analysis of hazards relating to explosion-proof enclosures which 
contain high-voltage switching; and, (5) Input from various technical 
experts throughout the mining community. These criteria are technically 
sound and have the general consensus of the mining community, including 
equipment manufacturers and other interested parties.
    The first high-voltage longwall system started operating in 1985. 
Since that time we have issued approximately 130 system design 
approvals for high-voltage longwall equipment. Over the last 16 years, 
no electrical-type fatalities or serious injuries occurred to miners 
because of high-voltage equipment used in accordance with over 100 
granted high-voltage petitions for modification (petitions). Because of 
this new improved high-voltage technology, the designed safety benefits 
and the observed use experience, MSHA is revising its existing 30 CFR 
part 18 electric motor-driven mine equipment and accessories approval 
requirements by adding specific design requirements

[[Page 10973]]

for high-voltage longwall equipment in underground mines.
    MSHA received comments from all segments of the mining industry, 
and the final rule addresses these comments. Many commenters were in 
favor of the new approval requirements and were in agreement on the 
majority of the provisions in the proposed rule. MSHA carefully 
reviewed all of the comments. This resulted in the modification of four 
of the sixteen technical requirements addressed in the proposed rule. 
We considered the views of all interested parties, including: mine 
operators; equipment manufacturers; miners' representatives; and other 
government agencies in developing this final rule.
    MSHA is publishing this high-voltage longwall approval rule (30 CFR 
part 18) along with mandatory safety standards regarding high-voltage 
longwall equipment (30 CFR part 75). This new 30 CFR part 18 rule 
provides additional high-voltage equipment specifications that must be 
followed by the manufacturer in order to obtain MSHA approval of the 
equipment. The new 30 CFR part 75 rule provides installation, use, and 
maintenance requirements for high-voltage longwalls in underground coal 
mines.

B. Part 75  High-Voltage Longwall Equipment Safety Standards

    This part of the final rule provides safety requirements for 
underground high-voltage longwall systems. Currently, longwall mining 
is permitted under MSHA's existing standards only if it uses low- or 
medium-voltage electrical power. High-voltage longwall systems are 
being used, but only when approved by MSHA through the petition for 
modification process under Sec. 101(c) of the Federal Mine Safety and 
Health Act of 1977 (Mine Act). During the last 15 years, MSHA has 
evaluated the safe use of high-voltage longwall equipment, under a 
petition process that permits a mine operator to request that the 
application of a safety standard be modified at a particular mine. MSHA 
grants a petition when it determines that a mine operator has an 
alternative method which provides the same measure of safety protection 
as the existing standard, or when the existing standard would result in 
diminished safety protection to miners. Over the past 15 years, MSHA 
has granted over 100 petitions for modification to use high-voltage 
electrical power with longwalls. In the Agency's evaluation of the use 
of high-voltage longwall mining systems, MSHA concluded that they can 
be safely used, provided that certain conditions are met. Specifically, 
the Agency found that the previous safety concerns about explosion, 
fire and shock hazards initially associated with high-voltage use are 
sufficiently addressed by this newly-developed technology. In each of 
the petition cases the Agency granted, MSHA performed a specific on-
site investigation to verify this finding. For example, we recognized 
that high-voltage electric equipment and circuit design improvements in 
combination with sensitive electrical circuit protections reduce fire, 
explosion and shock hazards. Newly designed cable handling systems 
provide additional safety protections against electrical shock, fire 
and explosion hazards when the cable is moved. Further, lighter power 
cables are available which reduce back strain and other injury risks to 
miners from the heavier cable lifting and hauling often associated with 
the moving or lifting of low- to medium-voltage cables. Moreover, there 
have been no electrical fatalities and no serious electrical injuries 
to miners from high-voltage equipment used under the granted 
modifications.
    Because of the new improved high-voltage technology, with its 
attendant safety benefits, MSHA is revising its existing 30 CFR part 75 
electrical safety standards. This final rule does not reduce the 
protection afforded by existing 30 CFR part 75 standards. It does, 
however, provide increased protection from electrical hazards, and 
reduces paperwork burden. It also reduces the time and cost to all 
parties associated with the petition for modification process. This 
final rule is implemented in conjunction with revisions to 30 CFR part 
18, that address approval requirements for high-voltage equipment. The 
additional requirements under 30 CFR part 18 are also consistent with 
advances in mine technology, allowing high-voltage switchgear to be 
used on face equipment with enhanced safety protection from fire, 
explosion and shock hazards.
    MSHA received comments from all segments of the mining community. 
Comments from labor, industry and manufacturers generally agree with 
the proposed rule. The final rule, to the extent feasible and 
appropriate, responds to commenters' concerns and reflects general 
consensus of various parties. However, MSHA did not adopt all comments 
received.
    Joint commenters representing both industry and labor recommended 
that operators mining under granted high-voltage petitions containing 
non-electrical provisions continue to comply with such provisions. 
Labor commenters requested that standards addressing high-voltage 
longwalls also include provisions addressing non-electrical safety and 
health areas. Specifically, they noted that high-voltage longwall 
systems of extended widths and lengths can adversely affect not only 
ventilation, but shearer mounted methane monitors, intake escapeways, 
exposure to respirable dust, tailgate travelways, and storage plans for 
self-contained self-rescuers (SCSR's), as well as return entry 
rockdusting during mining.
    It is the Agency's view that non-electrical safety and health 
issues related to the use of high-voltage longwalls are fully addressed 
by existing safety and health standards under 30 CFR parts 70 and 75. 
This view has been upheld by administrative law judge, Assistant 
Secretary and Court of Appeals decisions. UMWA v. Federal Mine Safety 
and Health Administration, 931 F. 2d 908,913 (D.C. Cir. 1991). The 
promulgated standards relating to ventilation and escapeways under 30 
CFR 75.300 et seq. (61 FR 9764, March 11, 1996) provide protection with 
respect to ventilation and escapeways. Mandatory health standards under 
part 70 address exposures to respirable dust. Section 75.215--Longwall 
mining systems--addresses longwall tailgate travelway protection. 
Storage plans for SCSRs may be approved by MSHA District Managers in 
accordance with the specific conditions at each mine under 
Sec. 75.1714-2--Self-rescue devices; use and location requirements. 
Existing Sec. 75.400--Accumulation of combustible materials--provides 
protection against float coal dust and Sec. 75.402--Rock dusting--
requires adequate rockdusting measures. MSHA continues to work on 
improved respirable dust protection requirements in response to 
recommendations made by the Secretary of Labor's Advisory Committee on 
the Elimination of Pneumoconiosis Among Coal Mine Workers.
    MSHA is aware that several granted modifications for high-voltage 
longwalls contain non-electrical requirements specific to the affected 
mine. These requirements are the result of settlement negotiations 
arising out of the petition process and are not required as part of 
this electrical standard. Parties to the current petition process may, 
through a voluntary, cooperative effort, continue to follow the non-
electrical provisions after this final rule becomes effective. 
Moreover, as indicated above, existing and new standards substantially 
address these concerns and result in no diminution of safety and health 
protection currently afforded to miners. Moreover, the Agency 
continually reviews existing standards for

[[Page 10974]]

improvements that will enhance miner safety.
    Some commenters suggested that the final rule allow a longer phase-
in period, where equipment modifications are necessary. The Agency does 
not believe that a delayed effective date is necessary. Many operators 
are already complying with these requirements under the petition for 
modification process and the modern technology necessary to implement 
the final rule is readily available.

II. Discussion of Final Rule

    The following section-by-section portion of the preamble discusses 
each provision affected, starting with the provisions in part 18. The 
text of the final rule is included at the end of the document.

Part 18  Electric Motor-Driven Mine Equipment and Accessories

    This final rule addresses only those areas where specific additions 
to 30 CFR part 18 are necessary for the approval of high-voltage 
longwalls. The existing requirements of 30 CFR part 18 that apply to 
this equipment have not been revised. Examples of these types of 
requirements are the general construction requirements of the high-
voltage enclosures and the short-circuit and overload protection to be 
provided. The overload and short-circuit protective device settings 
were not revised and will continue to be evaluated under existing 
requirements and Agency policy.
    The main safety protections addressed in the final 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; (3) Prevention of enclosure failure from an increased 
pressure rise if an arc or methane explosion occurs within the 
explosion-proof enclosure; and, (4) Personal protection for miners from 
electrical shock hazards when working in or around the high-voltage 
equipment.

Section 18.53  High Voltage Longwall Mining Systems (Nameplate Ratings 
From 1,001 Volts Through 4,160 Volts)

    Paragraph (a) of this final rule requires the separation of 
compartments containing low- and medium-voltage circuits from those 
with high-voltage circuits in each motor-starter enclosure by location, 
partitions or barriers. Partitions and barriers, under this final rule, 
like the proposed rule, are required to be constructed of grounded 
metal or nonconductive insulating board. These requirements protect 
against shock hazards which may arise from inadvertent contact with 
energized high-voltage circuits. With the exception of a controller on 
a shearer, compliance with this section requires the components within 
each high-voltage motor-starter enclosure be segregated into separate 
compartments by voltage classification. The installation of the 
barriers and partitions provides separation of components in each high-
voltage motor-starter enclosure. When complete separation of voltage 
classifications is not possible with barriers or partitions where both 
medium- and high-voltage circuits or both low- and high-voltage 
circuits are connected to a component or device, that component is 
required to be located in the motor contactor or disconnect device 
compartment.
    This rule covers both explosion-proof and nonexplosion-proof motor-
starter enclosures that are presently used by the mining industry. 
MSHA's policy has been to require barriers and partitions to separate 
the disconnect device compartment, control/communications compartment 
and motor contactor compartment in both power centers and motor-starter 
enclosures. If a motor-starter enclosure is part of a power center, 
then the partitions and barriers required by this rule only apply to 
barriers and partitions for the disconnect device compartment, control/
communications compartment, and motor-starter compartment of the power 
center. This rule does not apply to other parts of the power center or 
to separate power centers that supply power to motor-starter 
enclosures. The mining industry presently provides barriers for power 
centers to separate high-voltage components from low- and medium-
voltage circuits and equipment. MSHA encourages the industry to 
continue to provide barriers and partitions in power centers to 
minimize shock hazards by limiting exposure of personnel to high-
voltage components when troubleshooting and testing low- and medium-
voltage circuits. If barriers and partitions are not provided on power 
centers, the power center must be deenergized from an outby set of 
high-voltage visible disconnects and the high-voltage circuit grounded 
before troubleshooting and testing is performed on low- or medium-
voltage circuits or equipment in the same compartment with high-voltage 
circuits or equipment.
    Commenters suggested that, because of overall machine design 
considerations, an exception be provided for the controller on a 
shearer. In response to this comment, MSHA acknowledges that a shearer 
is a special case. The shearer is not required under Sec. 18.53(f) to 
have a disconnect switch. Therefore, in an effort to address this 
issue, the final rule has been modified exempting the requirements of 
paragraph (a) when applied to a shearer.
    One commenter recommended that the term ``location'' be deleted 
from the final rule, suggesting that there must be a physical 
separation within compartments to prevent accidental contact with a 
high-voltage circuit while troubleshooting low- and medium-voltage 
circuits. Another commenter proposed the use of separate compartments 
having explosion-proof walls between one compartment and the next. As 
noted in the proposed rule, the intent of this provision is to minimize 
shock hazards by preventing exposure of personnel to high-voltage 
components when troubleshooting and testing low- and medium-voltage 
circuits in accordance with Sec. 75.820. MSHA believes that this can be 
accomplished by various types of partitions or barriers, including 
designing the enclosure into several separate explosion-proof 
compartments. When designing the partitions or barriers, however, 
consideration should be given to possible effects of pressure-piling 
within the enclosure. The use of the word ``location'', in the proposed 
rule allowed the option of having separate enclosures to house the 
various compartments, as noted by the commenter. In response to these 
comments, the final rule removes the word ``location'' to provide for 
flexibility, but clarifies that the requirement applies to each motor-
starter enclosure.
    Comments were also received suggesting that we change the word 
``board'' to ``material'' in regard to construction of barriers and 
partitions. Since the word ``board'' suggests a more sturdy barrier 
than ``material,'' the final rule remains as proposed.
    Paragraph (b) of the final rule, like the proposed rule, requires 
motor-starter enclosure compartment(s) containing high-voltage 
components be provided with cover interlock switches. These interlock 
switches will protect miners entering enclosures from shock hazards 
resulting from accidental contact with energized circuits. A minimum of 
two interlock switches per cover is required and must be wired into the 
circuitry so that operation of either switch will deenergize the 
incoming high-voltage circuits. The Agency believes that a second 
switch coupled with required maintenance under 30 CFR 75.512 will 
provide the necessary protection to ensure that the high-voltage 
circuits are deenergized whenever a cover is

[[Page 10975]]

removed. MSHA recommends either a magnetic or a whisker-type switch. 
MSHA's follow-up inspections of high-voltage equipment with plunger-
operated switches reveal that these switches may stick and not operate 
effectively after exposure to the mine environment.
    This rule covers both explosion-proof and nonexplosion-proof high-
voltage motor-starter enclosures. MSHA's high-voltage longwall 
petitions require interlock switches for high-voltage compartments in 
both power centers and motor-starter enclosures. When a motor-starter 
enclosure is part of a power center, the interlock switches required by 
this rule only apply to motor-starter compartments of the power center. 
This rule does not apply to other parts of the power center or to 
separate power centers that supply power to motor-starter enclosures. 
The mining industry presently provides interlock switches for high-
voltage compartments on power centers. MSHA encourages the industry to 
continue to provide interlocks switches for high-voltage compartments 
of power centers.
    There were no comments on this paragraph. However, the last 
sentence of the proposed rule was deleted to clarify the Agency's 
intent that at least two switches be used to satisfy 30 CFR part 18.53 
(b) requirements.
    Paragraph (c) of the final rule, like the proposed rule, requires 
that circuit-interrupting devices installed in motor-starter enclosures 
be designed and installed to prevent automatic reclosure. Compliance 
with this provision protects miners working on the circuit or in other 
hazardous situations from unanticipated reenergization of the circuit. 
For example, faults occur in underground electrical systems as a result 
of roof fall damage or equipment insulation failure. Under such 
circumstances, the use of automatic reclosing circuit-interrupting 
devices would create shock and fire hazards should the devices reclose 
automatically when a short-circuit or ground-fault condition exists in 
the circuit. There were no comments on this paragraph. Therefore, the 
language in the final rule has not been changed from the proposed rule.
    Paragraph (d) of the final rule, like the proposed rule, specifies 
that control transformers installed in each longwall motor-starter 
enclosure or control transformers that supply control power to each 
longwall motor-starter enclosure, must have electrostatic (Faraday) 
shielding, grounded by at least a No. 12 American Wire Gauge (AWG) 
grounding conductor, installed between the primary and secondary 
windings. Compliance with this provision protects against shock hazards 
should a fault develop between the primary and secondary windings. 
Faraday shielding provides electrical isolation between the high-
voltage primary and low-voltage secondary windings of these 
transformers. As a secondary benefit, Faraday shielding of control 
transformers assures that transients occurring on the primary circuit 
are not transferred to the secondary circuit. Such transients could 
cause premature damage to electrical control equipment and create an 
economic burden for the mining industry.
    This rule requires Faraday shielding for control transformers 
located in both explosion-proof and nonexplosion-proof motor-starter 
enclosures that are presently used by the mining industry. Also, this 
rule requires Faraday shielding for control transformers that supply 
motor-starter compartments, even if the control transformer is located 
in a separate power center. This rule does not cover control 
transformers for power centers that do not supply power to the motor-
starter enclosure.
    Paragraph (d) also requires the secondary nominal voltage of the 
control transformer be no more than 120 volts, line-to-line. This is 
consistent with the existing policy interpretation of 30 CFR part 18 
control voltage limitations under Sec. 18.47. There were no comments on 
this paragraph and therefore, the wording remains the same as the 
proposed rule.
    Paragraph (e) of the final rule, like the proposed rule, requires 
test circuits to verify the integrity and proper operation of the 
ground-wire monitors and ground-fault protective devices. Test circuits 
for ground-wire monitors and ground-fault circuits assure that the 
circuits can be tested frequently in a manner that minimizes the 
hazards to personnel conducting the tests. Incorporating these test 
circuits into the longwall circuitry eliminates the need to test these 
protective devices by other means that could result in a shock hazard 
by placing personnel in close proximity to exposed energized 
conductors.
    Some commenters noted that the testing of backup ground-fault 
devices located across the grounding resistor would require the 
application of an actual phase-to-ground fault, which could be 
hazardous. These commenters suggested that the ground-fault test 
circuit inject a primary current into the transformer and not subject 
the equipment to an actual phase-to-ground fault. In addition, another 
commenter supported the opinion that it is a dangerous practice to test 
ground-fault protection by making direct connections between phase and 
ground, and stated that MSHA should establish a policy on this so that 
the matter is resolved.
    In response to these comments, unlike the proposed rule, the final 
rule includes a requirement that each ground-fault test circuit be 
designed to inject a primary current of 50 percent or less of the 
maximum ground-fault current through the current transformer to cause 
the corresponding circuit-interrupting device to open. This requirement 
is necessary to reduce the likelihood of a hazardous condition 
resulting from a phase-to-ground fault. A similar requirement is added 
to the final rule under 30 CFR 75.814(c).
    Paragraph (f) of the final rule requires each longwall motor-
starter enclosure, with the exception of a controller on a shearer, to 
be equipped with a disconnect device. Opening of the device deenergizes 
all high-voltage power conductors extending from the enclosure, except 
the conductors supplying power to the enclosure. Compliance with this 
paragraph provides for convenient and safe deenergization of high-
voltage circuits and other components during testing and 
troubleshooting work, thus minimizing shock hazards.
    A joint industry commenter suggested that the word ``incoming'' be 
inserted before the phrase ``disconnect device''. MSHA believes this is 
implied, since the device must deenergize all high-voltage power 
conductors extending from the enclosure. Therefore, the language of 
final rule remains as proposed.
    Paragraph (f)(1) of the final rule, like the proposed rule, 
specifies that a single handle provide for simultaneous operation 
through a mechanical connection of multiple switches located within an 
enclosure. The simultaneous operation of multiple disconnect devices by 
the use of a single handle ensures that all high-voltage conductors 
extending from the enclosure are deenergized when the disconnect device 
is in the open position. This arrangement ensures that personnel 
entering other enclosures are protected from a shock hazard resulting 
from accidental contact with energized circuits in the event the wrong 
circuit is disconnected.
    The words ``isolator switch'' and ``switches'' were removed in the 
final rule to minimize confusion. There were no comments on this 
paragraph and the language in the proposed rule remains unchanged 
except for the above clarifications.

[[Page 10976]]

    Paragraph (f)(2) of the final rule, like the proposed rule, further 
defines the requirements of a disconnect device. The switch must be 
rated for the maximum phase-to-phase circuit voltage of the system. The 
ability to verify, by visual observation, that the switch's contacts 
are opened is also required. This verification must be determined 
without the removal of any enclosure cover. The removal of an enclosure 
cover to verify opening of the contacts presents an increased shock 
hazard to miners because of exposed energized high-voltage components.
    Also included under this paragraph are the requirements that all 
load-side power conductors be grounded and the device be provided with 
a means to be locked when the device is in the ``open'' position. These 
requirements guard against the hazard of maintenance personnel being 
exposed to high-voltage energized parts due to residual voltage or 
inadvertent energization of the circuit.
    The final requirements of this paragraph address the interrupting 
capability of the disconnect device. A disconnect device installed in 
an explosion-proof enclosure must be designed and installed to cause 
the current to be interrupted automatically prior to the opening of the 
device. This requirement addresses the concern about an explosion-proof 
enclosure failure because of an increased pressure rise. This pressure 
rise can result when an arc or methane explosion occurs within the 
explosion-proof enclosure. When the enclosure is not explosion-proof, 
as in outby switching, the device is required to either be installed in 
the circuit so that the circuit is automatically interrupted prior to 
the opening of the device or the device is required to be capable of 
interrupting the full-load current of the circuit. There were no 
comments on this paragraph and the language in the proposed rule 
remains unchanged in the final rule.
    Paragraph (g) of the final rule addresses the interlocking of the 
disconnect device. These interlocking requirements reduce shock hazards 
by increasing the probability that the high-voltage circuits will be 
isolated and deenergized prior to performing testing and 
troubleshooting on the low- and medium-voltage circuits and ensure that 
high-voltage circuits may only be energized at the proper time 
following this activity.
    This rule covers both explosion-proof and nonexplosion-proof motor-
starter enclosures that are presently used by the mining industry. 
MSHA's policy has been to interlock disconnects with the control 
circuit in both power centers and motor-starter enclosures. If a motor-
starter enclosure is part of a power center, then this rule covers the 
power center. This rule does not apply to separate power centers that 
supply power to motor-starter enclosures. The mining industry presently 
provides this interlocking of the disconnect device for power centers. 
MSHA encourages the industry to continue to interlock disconnects with 
the control circuits to facilitate troubleshooting and testing high-
voltage circuits and equipment while the high-voltage circuits are 
disconnected. This maintains the existing level of protection because 
the interlock disconnects provide an additional safeguard against 
inadvertent exposure to energized high-voltage circuits.
    One commenter noted that the proposed rule calls for deenergizing 
the incoming high-voltage circuit if the normal/test auxiliary switch 
is not in the normal position while closing the main circuit-
interrupting device and the disconnect device (isolator switch). This 
commenter stated that this requirement would necessitate a retrofit in 
existing longwall controllers since the normal/test switch must be in 
the normal position when the disconnect switch is closed in order for 
the control circuit to function at all. This would prohibit the closing 
of the circuit-interrupting device and would disable the control 
circuitry. With the disconnect device in the open/grounded position, 
the test circuitry cannot be used unless the normal/test switch is in 
the test position. The commenter further indicated that, in either 
case, the incoming high voltage does not present a hazard.
    Other commenters recommended that the control circuits within each 
high-voltage motor-starter enclosure be interlocked with the disconnect 
device, except for the controller on a shearer, so that the control 
circuit can be powered with an auxiliary test switch when the 
disconnect device is in the open and grounded position; and the 
disconnect device cannot be closed without de-energizing the incoming 
high-voltage circuit unless the auxiliary test switch is in the normal 
operating position. These commenters stated that, in many cases, it is 
necessary to close the main circuit-interrupting device with the 
auxiliary switch in the test position.
    MSHA has carefully reviewed and considered these comments. The 
final rule retains the requirement that the control circuit for high-
voltage motor-starters can only be energized through an auxiliary test 
switch when the disconnect switch is open and the load power conductors 
of the high-voltage circuit are grounded. The proposed requirement that 
neither the main circuit-interrupting device nor the disconnect device 
can be closed without deenergizing the incoming high-voltage circuit 
unless the auxiliary test switch is in the normal operating position, 
has been replaced with a requirement which more clearly states the 
expected performance of the control interlock circuit. The final rule 
requires high-voltage control circuits to be interlocked so they can be 
energized only when the disconnect switch is either in the ``closed'' 
or the ``open and grounded'' positions. High-voltage control circuits 
may not be operated in any other intermediate positions of the 
disconnect switch or auxiliary switch. This requirement will prevent 
unintentional energization of high-voltage components. The control 
circuit can be energized only when the disconnect switch is ``open and 
grounded'' with the auxiliary switch in the ``test'' position, or when 
it is closed with the auxiliary switch in the ``normal'' position. MSHA 
has not included language in this paragraph to specifically exclude the 
controller on a shearer from these interlock requirements, as suggested 
by some commenters. Shearers are not required to be equipped with a 
disconnect device as stated in Sec. 18.53(f) of this final rule and 
MSHA does not intend that this provision be applicable to shearers. 
Therefore, except for the above stated clarifications, the final rule 
remains as proposed.
    Paragraph (h) of the final rule requires that the electrical 
protection be set at an appropriate value to provide protection for the 
size and length of the longwall motor and shearer cable used, based on 
an ``available fault current'' study that must be submitted to MSHA. 
Proper electrical protection is essential in preventing a fire, 
explosion or shock hazard resulting from inadequate sizing of 
electrical cables.
    Appendix I of existing 30 CFR part 18 includes maximum trailing 
cable protective device settings and trailing cable length restrictions 
as specified in Table 8 and in Table 9. These have, in the past, been 
used as guidance in evaluating cables on longwalls rated at less than 
1,000 volts. Under this final rule and consistent with agency policy, 
the length restrictions and device settings do not apply to high-
voltage longwall motor and shearer cables. The procedures used in 
evaluating high-voltage longwalls cables and settings include a review 
of the applicant's fault-current study to determine the minimum 
expected short-circuit currents available at the farthest projected 
installation in the electrical system.

[[Page 10977]]

    This paragraph of the final rule has been clarified, in response to 
a proposed 1989 electrical rule comment, to indicate that trailing 
cables would also be included in the required evaluation to ensure 
adequate protection for the length and conductor size of all cables, 
including longwall motor, shearer and trailing cables. However, MSHA 
does not intend to specify a fixed maximum setting for short-circuit 
protective devices, as noted by the commenter. MSHA intends to be 
flexible by assessing each installation individually. The submitted 
fault study is the basis in determining the settings, and for 
permitting higher trailing cable circuit protective device settings and 
cable lengths than specified by 30 CFR part 18. MSHA recognizes that it 
is practical to design longwall systems with higher circuit protective 
device settings and longer cable lengths in order to lessen economic 
burdens on the mining community while preserving safety and health 
protections for miners. Some commenters noted that the fault study is 
unique to each mine and that this requirement should not be included in 
30 CFR part 18. They suggested that the regulation is more suitable for 
inclusion in part 75. MSHA disagrees. In order for a longwall mining 
system to be safely designed, the designer must know the parameters 
under which the longwall will be operated. These parameters would 
include available fault currents. The final rule requires that this 
information be provided to MSHA to determine whether cables are 
adequately protected. Historically, longwalls are custom-made systems 
and are not designed for more than one mining company. The fault study 
should take into account worst-case projections (i.e., longest cable 
lengths, smallest Kilo-Volt Amperes (KVA) Power Center). Enforcement 
personnel will also use this information to ensure compliance with 
Sec. 75.518-1--Electric equipment and circuits; overload and short 
circuit protection; minimum requirements. Except as clarified above, 
the final rule remains as proposed.
    Paragraph (i) of the final rule requires all longwall motor and 
shearer cables with nominal voltages greater than 660 volts to have a 
cable construction with a grounded metallic shield around each power 
conductor. This regulation requires the incorporation of the grounded 
shield around each power conductor providing additional personnel 
protection against shock and electrocution hazards. This is necessary 
because any cable faults would cause phase-to-ground short-circuit 
currents to flow. An extra level of protection is achieved because the 
phase-to-ground short-circuit currents, unlike the phase-to-phase 
short-circuit currents that may flow from faults in other cable 
constructions, are limited in magnitude by the grounding circuit 
components.
    Some commenters suggested that these cables should be assembled 
with a grounded shield around each power conductor but that the shield 
should not be specified as metallic since these power systems restrict 
ground-fault current to reduced values and the cables are constantly 
flexed. They believed that an improved cable could be developed with a 
nonmetallic shielding material around each power conductor. In response 
to this comment, MSHA believes that this technology has not been 
demonstrated or shown to provide equivalent safety in underground coal 
mines. Although MSHA supports the application of new technology, 
questions such as splicing reliability would need to be addressed 
before incorporating these types of cables on longwalls. If a reliable 
system using this type of cable were developed and equivalent safety 
were demonstrated, it could be addressed under existing 
Secs. 18.20(b)--Quality of material, workmanship, and design and/or 
18.47(d)(6)--Voltage limitation through the construction and design 
requirements for MSHA approval. The final rule has not been modified, 
as suggested by commenters, and remains as proposed.
    Paragraph (j) of the final rule specifies that high-voltage motor 
and shearer circuits be provided with instantaneous ground-fault 
protection set at not more than 0.125-amperes. The current transformers 
(CT) used for ground-fault protection are required to be of the single 
window-type and installed to encircle all three phase conductors. This 
will provide highly sensitive and responsive ground-fault detection 
systems, using new technology such as solid state relays, for high-
voltage circuits supplying electric face equipment. The protective 
devices are required to operate instantaneously when exposed to ground 
faults that exceed the trip setting of the ground-fault protective 
device. Therefore, compliance with this standard will greatly reduce 
the likelihood of fires and shock hazards that result from ground 
faults on the high-voltage circuits or equipment.
    The use of the single window-type current transformer encircling 
all three phase conductors is the most reliable method for detection of 
ground faults in mine power systems. This type of relaying (zero-
sequence) is not affected by CT error and gives very sensitive 
tripping. This scheme is widely used in mining at all voltages. 
Requiring all three phase conductors to be encircled by the CT 
prohibits the equipment safety grounding conductors from passing 
through or being connected in series with the CT. If the safety 
grounding conductor passes through or is connected in series with the 
CT, it is possible for the fault currents to flow through parallel 
paths, thereby reducing the reliability of the ground fault protection.
    Some commenters suggested that if the full-load current of the 
circuit exceeds 200 amperes, the instantaneous ground-fault protection 
be set at not more than 0.200-amperes. They stated that it is very 
difficult to produce ground-fault current transformers that can 
reliably discriminate between small ground-fault currents and larger 
motor starting currents and that when the full-load current of a 
circuit exceeds 200 amperes, it is reasonable to expect motor starting 
currents in excess of 2,000 amperes. They asserted that a small 
increase in the setting of the ground-fault protection is justified for 
certain high-current circuits and that the suggested 0.200-ampere 
setting would still be less than 40 percent of the maximum ground-fault 
current. They noted that the specification of the current transformers 
is very rigid and stated that the regulation should allow for new 
technology if it can provide equal or improved protection. In relation 
to ground-fault protection, a commenter focused on MSHA's statement 
that zero sequence type relaying ``is not affected by CT error.'' The 
commenters stated that, in their experience, erroneous signals are 
produced in the CT's if the current levels are sufficiently high. They 
noted that when starting currents flowing in the power circuit are in 
excess of 2000A it is possible that an ``error current'' exceeding 
100mA may be fed to the relay, causing nuisance tripping. For this 
reason, it is their belief that the relays on the power center output 
cables to the longwall controls are now set to a higher current of 200-
300mA and these cables carry the combined starting currents of two or 
three motors. They concluded that as a result, when the size of 
individual motors gets larger, this problem will be experienced on 
motor cables.
    MSHA has reviewed these issues and determined that reliable, 
sensitive ground-fault protective devices are commercially available 
and that they have been successfully used to correct the problems 
described by the commenters. These devices can safely and reliably 
operate at 0.125-ampere or

[[Page 10978]]

less. The use of a single window-type current transformer to encircle 
only the three phase conductors assures that sensitive ground-fault 
devices will detect all ground faults exceeding the setting of the 
device. Detection devices inserted in the ground wire may not detect 
all ground-fault currents and could compromise the integrity of the 
ground circuit. Therefore, the final rule has not been modified and 
remains as proposed.
    Paragraph (k) of the final rule, like the proposed rule, requires 
safeguards against corona to be provided on all 4,160 volt circuits in 
explosion-proof enclosures. Corona is a luminous discharge that occurs 
around electrical conductors that are subject to high electrical 
stress. One danger inherent with high-voltage equipment is that 
excessive electrical stress can cause premature breakdown of insulating 
materials, which could result in arcing, thus creating an explosion 
hazard in the presence of corona. Corona usually doesn't present a 
hazard until voltage of 8kV are reached. However, even at 4,160 volts, 
safeguards should be taken. This 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. This provision is not intended to require stress cones or 
similar termination schemes. There were no comments on this paragraph. 
The final rule has not been modified and remains as proposed.
    Paragraph (l) of the final rule, like the proposed rule, requires 
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 protects against 
explosion hazards that may arise from the effects of a sustained high-
voltage arcing fault. This arcing fault may significantly contribute to 
the pressure rise created in an explosion-proof enclosure during an 
internal methane-air explosion. Research conducted by the former U.S. 
Bureau of Mines and MSHA on effects of high-voltage arcing in 
explosion-proof enclosures concluded that this potential increased 
pressure rise can be safely addressed through a combination of 
designing the enclosure for the increased pressure and providing 
electrical protective devices set to deenergize the incoming circuit 
before the pressure rise becomes excessive. This provision requires 
that the maximum explosion pressure rise must be limited to a value 
that can be safely contained within the explosion-proof enclosure (83 
percent of the design pressure). The final rule's performance-oriented 
language permits compliance through any achievable means. Protective 
methods used in previously issued approvals and experimental permits 
consisted of electrical devices with rapid clearing times. However, the 
rule provides for flexibility and permits alternative methods that may 
provide equal protection, such as pressure switches or special pressure 
release devices. There were no comments on this paragraph. The final 
rule remains as proposed.
    Paragraph (m) of the final rule, like the proposed rule, requires 
that high-voltage electrical components located in high-voltage 
explosion-proof enclosures cannot be coplanar with a single-plane 
flame-arresting path. This protective measure will further 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 addresses the possibility of conductor 
material particles being expelled from the enclosure through the flame-
arresting path. Particles of molten material are emitted from the 
conductors whenever a short-circuit occurs. 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 does not arise with multi-plane 
flame-arresting path surfaces because a deflection in the path would 
prevent ignitions by expelled particles. There were no comments on this 
paragraph. The final rule remains as proposed.
    Paragraph (n) of the final rule, like the proposed rule, addresses 
MSHA's concern with the decomposition of insulating materials due to 
tracking. In the presence of surface contaminants, small levels of 
current can flow between conductors. As the currents flow, the 
insulation may carbonize and produce conducting tracks. The conducting 
tracks may grow progressively across the surface eventually bridging 
between conductors and causing complete breakdown. Using insulation 
with an adequate Comparative Tracking Index (CTI) rating can prevent 
tracking, thus minimizing potential arcing that could lead to an 
explosion hazard. Paragraph (n) requires that rigid insulation between 
high-voltage terminals or between high-voltage terminals and ground be 
designed with creepage distances in accordance with the table labeled 
``Minimum Creepage Distances'' included in this section. The required 
creepage distances are determined based upon the phase-to-phase use 
voltage and the CTI of the insulation to be used. Creepage distance is 
based in part on the CTI of the electrical insulating material. 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 applies. There were no 
comments on this paragraph. The final rule remains as proposed.
    Paragraph (o) of the final rule addresses a requirement for Minimum 
Free Distance (MFD) within an explosion-proof motor-starter enclosure. 
MSHA's Internal Engineering Report Number 87021701 (available in the 
rulemaking record) determined that if phase-to-phase arcing occurred, 
there may be adequate arc energy to heat the walls of the enclosure 
beyond the safe working temperature. This could cause failure of the 
enclosure and create an explosion hazard. Distances between the wall or 
cover of an enclosure and uninsulated electrical conductors inside the 
enclosure were established to prevent wall or cover damage from phase-
to-phase arcing.
    Some commenters suggested that the last sentence of the proposed 
paragraph (o) be revised as follows: ``If a grounded \1/4\-inch thick 
steel shield is installed between the area of potential arcing and the 
adjacent wall/cover area, the minimum free distance requirement is 
satisfied.'' MSHA believes that this comment was based on a footnote 
present in the part 18 approval criteria established by MSHA for high-
voltage equipment containing on-board switching of high-voltage 
circuitry. This criteria indicates that the specified MFDs may be 
reduced if a \1/4\" thick steel shield is used between the area of 
potential arcing and the adjacent wall/cover area. Since this footnote 
did not cite a MFD or qualify the circumstances under which this shield 
could be used, MSHA did clarify this criteria exception in the proposed 
rule, and the final rule remains unchanged with respect to this 
clarification. A commenter also stated that a steel shield could be 
mounted in conjunction with an aluminum wall or cover to reduce the 
required minimum free distance and that the thickness of this steel 
shield would be used to determine the required minimum free

[[Page 10979]]

distance. MSHA has determined that a \1/4\" thick steel shield, mounted 
to maintain a minimum electrical clearance, as suggested by the 
commenter, would not provide sufficient protection if a phase-to-phase 
arc occurred. The final rule also permits the use of steel shields 
greater than \1/4\" thick to provide for flexibility and 
diversification in enclosure design.
    Some commenters noted that the proposed regulation classified all 
enclosures in one of two groups: those with short-circuit currents less 
than 10,000 amperes and those with short-circuit currents between 
10,000 and 20,000 amperes. It was their view that because of the 
substantial increase in minimum free distance between these groups, 
MSHA should permit a manufacturer to calculate the appropriate MFD when 
the short circuit current is between 10,000 amperes and 20,000 amperes. 
They also recommended that MSHA include a provision that would permit 
the minimum free distances to be revised based on future research in 
this area. Finally, they noted that the MFD for a 1-inch thick cover 
under Column A was omitted.
    In response to these comments, MSHA has revised the Minimum Free 
Distance Table by adding minimum free distance information for short-
circuit currents of 15,000 amperes. Additionally under the final rule 
in paragraph (o)(1), MSHA allows for values not presented in the table 
provided that they meet the specific engineering formulas on which the 
table is based. These formulas were developed by MSHA engineers with 
standard engineering calculations using data obtained from high-energy 
arc testing. This testing was performed during Foster-Miller research, 
under USBM Contract No. H0308093. The MSHA research reports and data 
are part of the rulemaking record and are available for review.
    Equipment approved under these circumstances will be limited to 
equipment used only with power systems that do not generate short-
circuit currents that exceed the design parameters used for 
establishing minimum free distance. In addition, MSHA will consider the 
use of shields constructed with alternate materials and the use of 
alternate techniques and methods that preclude the possibility of high-
energy arcs heating the walls of explosion-proof enclosures beyond safe 
working temperatures. If upon evaluation, equivalent safety is 
demonstrated, MSHA will address these technological advances and the 
results of additional research in this area, if warranted, under 
Secs. 18.20(b) and/or 18.47(d)(6). MSHA intentionally omitted the MFD 
value for a 1" thick steel wall/cover under Column A to minimize 
confusion. MSHA calculated this value to be 0.3", which is less than 
the minimum electrical clearance that must be maintained under 
Sec. 18.24 for high-voltage equipment. As indicated above, the proposed 
rule has been modified in part, and adopted in part.
    Paragraph (p) of the final rule, like the proposed rule, requires a 
static pressure test to be performed on each prototype design of 
explosion-proof enclosure housing high-voltage switchgear prior to 
explosion tests. The manufacturer is also required to use this test as 
a routine test on every explosion-proof enclosure housing high-voltage 
switchgear, at the time of manufacture, or follow an MSHA accepted 
quality assurance procedure covering the inspection of the enclosure. 
These quality assurance procedures must include a detailed check of 
parts against the drawings to determine: (1) That the parts and the 
drawings coincide and (2) that the minimum requirements stated in 30 
CFR part 18 have been followed with respect to materials, dimensions, 
configuration and workmanship.
    MSHA is concerned about the specified design pressure of an 
enclosure. Presently, an enclosure that is designed for 150 pounds per 
square inch gauge (PSIG) is tested with a methane explosion. Normally, 
these pressures do not exceed 100 pounds per square inch (PSI). Since 
the protective method to prevent over-pressurization in these 
enclosures would be directly related to the design pressure, MSHA has 
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 enclosure prototype, MSHA believes that the adequacy of 
enclosure design would be verified. Additionally, to require either 
subsequent static pressure testing on each enclosure manufactured or an 
acceptable quality assurance program guarantees the integrity of later 
manufactured units.
    The static test procedure 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. Following the 
pressure hold, the pressure is removed and the pressurizing agent 
removed from the enclosure.
    Acceptable performance criteria are provided in this final rule. 
Acceptable performance is achieved if the enclosure, during 
pressurization, does not exhibit leakage through welds or casting or 
rupture of any part that affects the explosion-proof integrity of the 
enclosure. Further, the enclosure, following removal of the 
pressurizing agents, must 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 the above conditions would 
constitute unacceptable performance.
    There were no comments on this paragraph. However, the final rule 
is modified to clearly state the type and nature of quality assurance 
inspections that qualify as an MSHA accepted quality assurance 
procedure.

Part 75  Mandatory Safety Standards--Underground Coal Mines

    The final rule revises existing standard Sec. 75.1002--Location of 
trolley wires, trolley feeder wires, high-voltage cables and 
transformers, and adds Secs. 75.813 through 75.822 to set out 
additional safety precautions that allow the use of available 
technology. These new safety precautions address the use of high-
voltage longwall equipment in face (production) areas. As stated 
earlier, MSHA previously included these safety precautions in petitions 
granted for Sec. 75.1002. Based on its experience with petitions for 
modification, the agency expects the final rule to improve safety for 
underground coal mining.
    Under the final rule, the risk of injury related to lifting and 
handling of cables should be reduced since the use of high-voltage 
cables can reduce the weight and size of a cable used in longwall face 
systems.
    The final rule also provides the following protection against fire, 
explosions, and/or shock hazards:
    (1) Improved short-circuit and ground fault protection;
    (2) A means to easily test the effectiveness of ground fault 
protection;
    (3) Use of manufactured cable support systems for cables extending 
from the power center to the headgate;
    (4) Use of insulated cable-handling equipment;
    (5) Use of protective gloves to troubleshoot and test low- and 
medium-voltage circuits associated with high-voltage circuits;
    (6) Use of additional protection for cables at points where cables 
leave support systems;
    (7) Use of more improved ``quick handle'' disconnect devices for 
the purpose of performing work; and
    (8) The use of barriers and interlock switches to help guard 
against contact

[[Page 10980]]

with energized circuits. The final rule requires the use of cables 
containing metallic shielding (SHD) around each power conductor.
    Many of these final rule safety improvements are required 
conditions for granted modifications of Sec. 75.1002. However the final 
rule, like the proposed rule, provides two additional requirements. 
These are gloves for troubleshooting and testing, and test circuits for 
ground-fault protection.
    The final rule, in response to commenters' suggestions, also 
provides two provisions not included in the proposed rule, 
Secs. 75.814(e) and 75.822. Section 75.814(e) requires a single circuit 
interrupting device for cables connected in parallel or permits 
parallel circuits-interrupting devices to protect parallel cables when 
the parallel circuit-interrupting devices are electrically and 
mechanically interlocked. Section 75.822 allows the use of No. 16 AWG 
ground-monitor conductors. These additional provisions are a logical 
outgrowth of the proposed rule and notice and comment process, 
reflecting the primary purpose of the proposed rule by allowing the use 
of high voltage on longwalls in a safe and efficient manner. The new 
provisions are in response to specific joint industry and labor 
comments received about parallel circuit use, and industry comments 
about the size of ground-check conductors. These additional provisions 
permit the use of high-voltage longwall systems that are safe, 
effective and efficient and reflect the mining community's experience 
with granted modifications. The ground-monitor conductor size and the 
multiple parallel circuit provisions are not requirements but are 
offered to give flexibility to mine operators to use available 
technology and to minimize cost burdens where feasible.
    Section 75.814(e) of the final rule requires that multiple 
(parallel) circuits be protected by a single circuit-interrupting 
device rather than parallel connected circuit-interrupting devices, 
except when parallel devices are mechanically and electrically 
interlocked. This requirement is based on MSHA electrical safety 
experience, and experience in granting high-voltage longwall petitions 
for modification, and is consistent with requirements under nationally 
recognized consensus standards. Although multiple parallel circuits are 
not necessary for safe high-voltage longwall systems, they do present 
certain safety and cost efficiency advantages to some longwall high-
voltage systems as demonstrated under MSHA's and the mining industry's 
petition experience. Higher currents can be used without increasing 
voltage levels which helps minimize cable over-heating and reduces 
cable insulation deterioration. Multiple parallel circuits in these 
systems are a logical option that resulted from this high-voltage 
longwall petition experience. As noted above, industry and labor 
suggested multiple parallel circuit use during the rulemaking comment 
process.
    Section 75.822 allows the use of high-voltage longwall cables with 
a minimum No. 16 AWG center ground-monitor conductor. This provision 
eliminates the need for petitions for modification of Sec. 75.804(a). 
It allows the use of improved high-voltage cable designs that provide 
increased protection against fire and shock hazards. It reduces inter-
machine arcing from induced currents which can result in an ignition 
hazard. The cable designs were initially developed for high-voltage 
longwall equipment under previously granted petitions.
    The cable design requirements were also requested by labor and 
industry during the comment period of the proposed rule. Since 1992, 
under MSHA-approved petitions, these cable designs have been safely 
used.
    These new requirements not only permit multiple parallel cable use 
and the use of No. 16 AWG ground-monitor conductors but also minimize 
industry paperwork requirements. With this new technology, the final 
rule results in improved safety and savings for both the mining 
community and MSHA. Cable replacement and maintenance costs will be 
reduced. Also, mine operators will not need to file petitions for 
modification; therefore, costs associated with the petition process 
will be eliminated. Legal costs are incurred by all segments of the 
mining community in the administrative review process associated with 
petitions. Agency costs associated with publication, processing, 
investigation and review of high-voltage longwall petitions will also 
be eliminated.
    The final rule increases safety protections and does not reduce the 
protections currently afforded miners.

Section 75.2  Definitions

    The definitions in this section are key to proper interpretation of 
the electrical standards. Upon review, the Agency concluded that these 
definitions should also be used to describe these terms wherever they 
appear in 30 CFR part 75 and proposed such an approach. This approach 
will provide clarity and consistency in the use of these terms where 
they appear in all underground safety standards. All underground coal 
mine operators and miners representatives were sent copies of these 
proposed definitions as part of the complete longwall high-voltage 
proposed rule. There were no comments opposing this approach.
    The definitions are derived from consensus standards, including the 
Institute of Electronic and Electrical Engineers, The New Standards 
Dictionary of Electrical and Electronics Terms--Standard 100-1992, and 
the National Electrical Code (NEC). Definitions found in 30 CFR part 18 
of MSHA's regulations were also used as a source for this final rule. 
In some instances, definitions taken from these sources were changed to 
apply to electric circuits and equipment used in the coal mining 
industry.
    MSHA proposed that the term ``adequate interrupting capacity'' be 
defined as the ability of an electrical protective device to safely 
interrupt all values of current which can occur at its location in 
excess of its trip setting or melting point. A commenter suggested that 
this term be defined as the ability of an electrical protective device, 
based upon its required and intended application, to safely interrupt 
values of current in excess of its trip setting or melting point. MSHA 
agrees and has changed the proposed definition to reflect this 
suggestion. This commenter suggested that the proposed definition would 
cause a problem, since in motor-starter enclosures of the type 
presently used for high-voltage longwalls, short-circuit protection is 
provided by a single circuit breaker common to all motor circuits, 
whereas overload, ground fault, and ground-monitor protection trips 
individual motor contactors. According to this commenter, this could 
result in the interruption of the intended protected circuits at a 
higher current value than was intended or required for that circuit, 
therefore, affording less protection against overheating, shock and 
fire hazards. The commenter further suggested that in applying the 
revised definition, the short-circuit relay signals the circuit breaker 
to interrupt the short-circuit current, whereas the ground-fault relay 
signals the contactor to interrupt the restricted ground-fault current. 
Under the final rule, adequate interrupting capacity is determined by 
comparing the interrupting rating of the device with the actual 
characteristics of the circuit to be protected. Thus, interruption of 
the circuit occurs at the current rating required or intended for that 
circuit rather than all values of current which can occur at its 
location.
    The final rule defines ``approval documentation'' to mean formal 
papers issued by the Mine Safety and Health Administration which 
illustrate and

[[Page 10981]]

describe the complete assembly of electrical machinery or accessories 
that have complied with the applicable approval requirements of 30 CFR 
part 18. The rule retains the meaning of the proposed rule but, for 
clarification purposes, replaces ``formal document'' with the words 
``formal papers'' and the verb ``document'' with the words ``describe 
and illustrate''. The proposed language was also changed to accurately 
reflect that ``approval documentation'' refers to those papers that 
illustrate and describe equipment meeting the ``applicable requirements 
of 30 CFR part 18.'' This change clarifies that approval documentation 
must be submitted under part 18. MSHA received no comments in regard to 
this definition.
    Like the proposed rule, the final rule defines ``circuit-
interrupting device'' as a device designed to open and close a circuit 
by nonautomatic means and to open the circuit automatically at a 
predetermined overcurrent value without damage to the device when 
operated within its rating. The Agency received no comments on this 
definition and it is unchanged from the proposed rule. This definition 
clarifies that circuit-interrupting devices be designed for manual 
closure rather than automatic, to protect against safety hazards which 
could result in severe bodily injury and death if unexpected automatic 
energization of equipment were to occur. Conversely, the device must be 
capable of opening the circuit automatically upon the occurrence of an 
electrical fault. The rating of the device must be at a value that 
would protect the device from damage during the automatic 
deenergization of the circuit.
    ``Ground fault or grounded phase'' is defined to mean an 
unintentional connection between an electric circuit and the grounding 
system. MSHA received no comments on this definition and it remains 
unchanged from the proposed rule.
    Like the proposed rule, the final rule defines ``motor-starter 
enclosure'' to mean an enclosure containing motor starting circuits and 
equipment. This term describes equipment commonly used to house 
longwall motor-starting equipment. No comments were received on this 
definition and it remains unchanged.
    Also like the proposed rule, the final rule defines ``nominal 
voltage'' to mean the phase-to-phase or line-to-line root-mean-square 
value assigned to a circuit or system to conveniently designate its 
voltage class, such as 480 or 4,160 volts. The definition clarifies 
that the actual operating voltage of a system or circuit may vary from 
its nominal voltage within a range that permits satisfactory operation 
of equipment. The Agency received no comments on this definition and it 
has not been changed.
    The final rule, like the proposed rule, defines ``short circuit'' 
to mean an abnormal connection of relatively low impedance, whether 
made accidentally or intentionally, between two points of different 
potential. There were no comments on this definition so it remains 
unchanged.
    Definitions of low voltage, medium voltage, and high voltage were 
inadvertently included in the proposed rule. No comments were received 
on these definitions. These terms are defined in existing rules and are 
not addressed in this final rule.
    One commenter suggested that ``cable handling and support system'', 
a phrase used frequently in Sec. 75.817--Cable handling and support 
systems, should be defined. Section 75.817 contains the performance 
goals that cable handling and support systems must achieve, by 
minimizing the possibility of miners coming into contact with cables 
and protecting the high-voltage cables from damage. The Agency does not 
believe that a definition is necessary for this term. Specifically 
defining a cable handling and support system would limit operator 
flexibility with respect to cable handling and support systems that may 
be designed in the future and provide equal or greater safety 
protection. Cable handling and support systems are understood by the 
plain meaning of the words.

Section 75.813  High-Voltage Longwalls; Scope

    Section 75.813 describes the scope of this final rule; it 
identifies new Secs. 75.814 through 75.822 as electrical standards that 
apply only to the use of high-voltage longwall circuits and equipment. 
The final rule, unlike the proposed rule, expands the scope to include 
new Sec. 75.822. As explained below, Sec. 75.822 is included in the 
final rule in response to a comment regarding the size of ground-
monitor conductors in cables. This provision also eliminates the need 
for petitions for modification related to ground-monitor conductor 
size. This section also clarifies that all other existing standards in 
30 CFR that are applicable to the use of high-voltage longwall circuits 
and equipment continue to apply. 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 longwall equipment.
    Some commenters suggested that an exception should be made in the 
standard for shearing machines that have been previously evaluated by 
MSHA under part 18, using non-high-voltage criteria. However, such an 
exemption would exclude shearing machines from the general safety 
requirements contained in the final rule. Safety requirements 
pertaining to electrical work, such as troubleshooting and testing, and 
installation, examination and maintenance, contain provisions that 
apply to all equipment on the high-voltage longwall, including shearing 
machines. Other provisions relating to disconnect devices and cable 
handling and support systems are applicable to the equipment they 
address. Therefore, the Agency does not believe that a general 
exemption for shearing machines would promote safety.

Section 75.814  Electrical Protection

    This section of the final rule is derived in part from existing 
Secs. 75.518-1--Electric equipment and circuits; overload and short 
circuit protection; minimum requirements, 75.800--High-voltage 
circuits; circuit breakers, and 75.800-2--Approved circuit schemes and 
addresses electrical protection methods for longwall equipment supplied 
by high-voltage systems. The effects of ground faults, electrical 
arcing, heating of conductors, and short circuits can have adverse 
consequences to the safety of miners. Effective electrical protection 
for longwall equipment will reduce the potential for ignitions, fires, 
and miner exposure to energized equipment frames. The final rule 
incorporates the latest technology and provides increased worker 
protection for high-voltage longwall mining equipment.
    Paragraph (a) of the final rule addresses requirements for short-
circuit, overload, ground fault, and undervoltage protection for high-
voltage cables extending from the section power center, the shearer 
motor cable(s), and the remaining motor cables. Short-circuit and 
overload protection prevent damage to cables and motors due to 
overheating. Ground-fault protection minimizes the risk of shock 
injuries and ignition hazards to miners. Under-voltage protective 
devices prevent automatic restarting of equipment following a loss of 
power.
    The final rule also requires circuit-interrupting devices for high-
voltage circuits that supply power to longwall equipment be properly 
rated to safely interrupt the current to which it may be exposed 
without damage. The adequacy of the circuit-interrupting device assures 
that the device will remain undamaged by overcurrents and faults in the 
system.

[[Page 10982]]

    One commenter requested clarification regarding whether vacuum 
contactors can be used to provide ground-fault and overload protection 
since some have been approved for use on longwall controllers. Vacuum 
contactors are a vacuum sealed system as opposed to a circuit breaker, 
which interrupts the arc in air or oil. The final rule permits the use 
of vacuum contactors as long as these contactors meet the definition of 
a ``circuit-interrupting device.''
    Some commenters submitted sketches of high-voltage longwall 
circuits, and requested an evaluation of whether the circuits would 
comply with the standard. It is beyond the scope of this rulemaking for 
MSHA to evaluate and approve such submissions. Systems and wiring 
designs can vary from mine to mine and from section to section within 
the same mine, depending on factors such as control circuit 
configuration, load terminations, and available fault current. MSHA 
will evaluate these designs on a case-by-case basis as mine operators 
plan to implement high-voltage longwalls at their mines and during the 
approval process under the applicable 30 CFR part 18 provisions.
    Paragraph (a)(1) of the final rule, like the proposed rule, 
specifies a current setting for short-circuit protective devices. The 
devices, whether located in the section power center or the longwall 
motor-starter enclosure, are required to be set at the lower value of 
either the setting specified in the approval documentation pertaining 
to the longwall system, or 75 percent of the minimum available phase-
to-phase short-circuit current. The short-circuit current settings 
specified during MSHA's approval process are based on the calculation 
of fault currents at various key locations in the system.
    The results of a 1992 Agency study of fault current levels in 30 
high-voltage longwall systems indicate that phase-to-phase short-
circuit currents range between 1,500 and 9,000 amperes at the various 
motor locations. (A copy of this study is available as part of the 
record.) Therefore, current (ampere) settings of 75 percent of the 
minimum phase-to-phase short-circuit currents will establish maximum 
limits for trip settings of short-circuit current devices. As equipment 
is used and moved from one location to another in a mine, changes take 
place in both the equipment and electrical system that indicate a need 
for a change in settings for short-circuit protective devices. Some 
commenters suggested that a statement be added to this provision 
indicating that the minimum available short-circuit current be 
determined by calculations and not by actual in-mine short-circuit 
tests.
    To date, it has not been necessary to conduct in-mine testing for 
the purpose of making determinations of proper settings of short-
circuit protective devices. However, the method used to make these 
determinations should not be restricted to calculations, since unusual 
or unanticipated conditions, such as high motor starting currents, may 
require in-mine testing.
    Paragraph (a)(2) of the final rule specifies short-circuit time 
delay settings for protective devices. Short-circuit devices protecting 
cables extending from section power centers to motor-starter enclosures 
may incorporate time delays limited to the settings specified in the 
approval documentation or 0.25-second, whichever is less. This 
paragraph revises the proposed rule to allow short-circuit devices 
protecting motor or shearer circuits to incorporate intentional time 
delays. The time delays may be limited to the settings specified in the 
approval documentation, or up to three cycles (0.050-seconds), 
whichever is less. The purpose of permitting a time delay is to prevent 
nuisance tripping during motor starting. When high-voltage longwall 
equipment was introduced to the mining industry, nuisance tripping 
problems were experienced. This nuisance tripping was caused by motor 
starting currents. In order to solve these problems, it may be 
necessary to incorporate time delays into the short-circuit protective 
devices. Currently, electronic relays that have a time delay to 
override motor starting currents are commonly used to provide short-
circuit protection for high-voltage longwall circuits.
    The proposed rule allowed time delays for short-circuit devices 
protecting cables extending from power centers to motor-starter 
enclosures. The maximum value of the time delay was limited to the 
smaller of the value specified in the approval documentation or 0.25-
second (15 cycles). However, the proposed rule did not provide for time 
delays to be incorporated into short-circuit devices protecting motor 
or shearer cables. The Agency specifically solicited comments regarding 
elimination of intentional time delays and allowing higher short-
circuit settings based on system capacity.
    One commenter stated that time delays between the longwall 
controller and section power center should be required to permit 
adequate coordination with downstream devices. According to the 
commenter, if there is a failure in the utilization circuit, for 
example, the crusher motor, it is advantageous for the failure to be 
cleared by the circuit-interrupting device in the controller, not the 
section power center which acts as a back-up. This commenter further 
stated:
    (1) Without the presently permitted time delays, the fault would 
also deenergize the transformer, and more than likely, personnel would 
reenergize the circuitry to find the location of the fault in the 
system;
    (2) This unnecessary closing in on a faulted circuit is eliminated 
when the circuits are properly coordinated; and
    (3) Time delays should be kept as short as possible to provide 
adequate coordination.
    Other commenters suggested that time delays be eliminated and 
higher short-circuit settings be allowed based on system capacity, 
provided that the Agency develops test scenarios to determine the safe 
time delay settings. These commenters stated that elimination of time 
delays would offer protection in the event of a direct fault because 
there would not be resistor strips (overloads) available to open the 
circuit and remove the power. They stated that inspections have 
revealed that, in some cases, resistor strips are either not operable, 
damaged, or have been by-passed.
    After careful review of this issue, the Agency has concluded that 
the use of time delays and subsequent lower short-circuit settings 
would result in coordination (selective tripping) of circuit-
interrupting devices. Proper coordination of circuit-interrupting 
devices can result in improved safety since faulted circuits can be 
more easily and safely identified and isolated for the purpose of 
troubleshooting, testing, and repair work. Commenters also suggested 
that time delay settings of short-circuit protective devices used to 
protect any cable extending from the section power center to a motor-
starter enclosure not exceed the settings specified in approval 
documentation or 0.30-second (18-cycles), whichever is less.
    This provision is not changed from the proposed rule. MSHA's 
experience has been that the maximum time delay for reliable 
coordination is 0.25-second (15-cycles). Further, a joint standard 
published by the American National Standards Institute (ANSI) and the 
Institute of Electrical and Electronics Engineers, Inc., entitled IEEE 
Recommended Practice for Protection and Coordination of Industrial and 
Commercial Power Systems (IEEE Buff Book)--Standard 242-1986, allows 
0.25-second time-delay to ensure reliable coordination of short-circuit 
protective devices. Therefore, an increase to 0.30-second is not 
justified.

[[Page 10983]]

    These commenters further suggested that short-circuit protective 
device settings, used to protect motor and shearer circuits, should be 
based on the maximum asymmetrical starting current with no intentional 
time delay or be based on the maximum symmetrical starting current with 
a time delay of no more than 0.050-second (three-cycles). These 
commenters pointed out that modern electronic short-circuit protective 
devices can be made to operate within one cycle (0.017-second). These 
devices will respond while the motor or shearing machine starting 
current contains an appreciable asymmetrical component and the 
asymmetrical component of the motor or shearing machine starting 
current will be negligible near 0.050-second. They suggested that 
introducing a 0.050-second time delay will permit a significant 
reduction in the setting of the short-circuit protective devices. 
Another commenter suggested that it is important to recognize the 
difference between asymmetrical motor starting currents that persist 
for two (0.033-second) to three cycles (0.050-second) following 
contactor closure, and motor starting currents that persist for several 
seconds. This commenter pointed out a need for two cycles time delay. 
MSHA agrees that there is a difference between asymmetrical motor 
starting currents and symmetrical motor starting currents which can 
last for several seconds.
    Therefore, the final rule permits limited time delays to be used in 
conjunction with lower settings of short-circuit protective devices 
rather than higher settings of short-circuit protective devices without 
time delays. This should result in proper coordination and subsequent 
selective tripping of circuit-interrupting devices and prevent nuisance 
tripping of circuit-interrupting devices due to high motor starting 
currents. In response to comments, the Agency concludes that a time 
delay will be necessary to allow proper starting of motors. Therefore, 
this provision allows short-circuit devices protecting motor or shearer 
circuits to incorporate intentional time delays limited to the settings 
specified in the approval documentation, or up to three cycles (0.050-
seconds), whichever is less.
    Paragraph (a)(3) of the final rule, like the proposed rule, 
requires ground-fault currents to be limited by a neutral grounding 
resistor to not more than 6.5 amperes when the nominal voltage of the 
power circuit is 2,400 volts or less, or 3.75 amperes when the power 
circuit voltage is greater than 2,400 volts. Typically, the mining 
industry has used grounding resistors in resistance-grounded systems 
that limit the ground-fault current in a circuit to 0.50 to 1.00 
ampere. MSHA encourages this practice to continue. The levels specified 
in the final rule allow new technology to detect lower ground-fault 
currents and reduces shock hazards. During ground-fault conditions, the 
grounding resistor will dissipate heat. The final rule limits the heat 
dissipation by the grounding resistors to a value equivalent to the 
heat dissipated by grounding resistors that have been in service for 
numerous years on medium-voltage longwall systems. The specified values 
prevent grounding resistor enclosures from overheating and becoming 
ignition or fire sources. There were no comments on this provision and 
therefore it remains as stated in the proposed rule.
    Paragraph (a)(4)(i) of the final rule, like the proposed rule, 
requires high-voltage circuits extending from the section power center 
to have ground-fault protection set at not more than 40 percent of the 
current rating of the neutral grounding resistor. These protective 
devices assure that circuits extending from the section power source 
will be quickly deenergized when they are subjected to ground faults. 
The final rule uses the current ratings for grounding resistors, 
specified in paragraph (a)(3), as a basis for setting ground-fault 
devices. For example, if a 6.50 ampere grounding resistor is used, the 
ground-fault device must operate to deenergize the circuit at 2.60 
amperes (40 percent) or less. If a 0.50-ampere grounding resistor is 
used, the ground-fault device must operate to deenergize the circuit at 
200 milliamperes or less. The 40 percent trip level provides a safety 
factor to assure that unexpected lower levels of ground-fault current 
would be detected and cause the circuit-interrupting device to open. 
This value also allows proper trip coordination with other protective 
devices. There were no comments on this section of the rule and the 
final rule adopts the language used in the proposed rule.
    Paragraph (a)(4)(ii) of the final rule, like the proposed rule, 
requires backup ground-fault protection to detect an open grounding 
resistor. The ground-fault protective device can be a combination of a 
potential transformer and voltage relay, or another device(s) capable 
of detecting an open neutral resistor. Once an open neutral resistor is 
detected, the ground-fault protective device must cause the circuits 
extending from the power center to be deenergized. There were no 
comments on this section of the rule and it remains as stated in the 
proposed rule.
    Paragraph (a)(4)(iii) of the final rule requires thermal protection 
for the high-voltage neutral grounding resistor, which opens the 
ground-check circuit for the high-voltage circuit supplying the section 
power center, if the grounding resistor is subjected to a sustained 
ground-fault current. The overtemperature rating or setting must be 50 
percent of the maximum temperature rise of the grounding resistor or 
150 deg.C (302 deg. F), whichever is less. The final rule is changed 
from the proposed rule to also allow the use of a current transformer, 
and a thermal overcurrent relay to provide the required thermal 
protection. The final rule uses the term ``thermal protection'' rather 
than ``overtemperature protection'' to permit current transformers and 
thermal relays or other devices such as thermostats that react to 
overtemperature. This change allows new technology developed by the 
mining industry during the last seven years.
    A commenter questioned the need for these devices. In response, 
grounding resistors generate heat when subjected to sustained ground-
faults. An overtemperature device causes interruption of the high-
voltage circuit supplying the section power center by opening the 
ground-wire monitor circuit before extreme heat destroys the grounding 
resistor function. Failure of the resistor leaves the circuit 
unprotected against ground-faults and increases the possibility of fire 
and shock hazards. The commenter also requested a six-month delay in 
implementing this provision to allow mine operators to acquire high 
quality devices. It is MSHA's view that since these devices have been 
required to be installed on high-voltage longwall mining systems for at 
least the past seven years under petitions granted for Sec. 75.1002, 
the devices should be readily available for use. A six month delay is 
not necessary.
    Another commenter wanted the maximum temperature for the 
overtemperature device to be set at 150 deg. C. This setting was 
incorporated into the 1992 proposed rule. Some commenters suggested 
that overtemperature protection should remove power from the power 
center transformer if the grounding resistor is subjected to a 
sustained ground fault. These commenters pointed out the following:
    (1) Many power centers are equipped with an incoming high-voltage 
circuit breaker to provide protection for the transformer;
    (2) The overtemperature protection for the grounding resistor could 
cause this circuit breaker to open in the event of a sustained fault; 
and

[[Page 10984]]

    (3) This would remove the ground fault and make troubleshooting 
more convenient.

MSHA agrees that the use of an incoming high-voltage circuit breaker 
may be an acceptable device for removing power from the section power 
center when the overtemperature device is activated. However, 
activation of the grounding resistor overtemperature protection could 
be an indication of serious problems in the tripping circuits for the 
circuit-interrupting device(s) located in the power center. This 
condition warrants complete removal of power from the entire power 
center until the condition is properly investigated and corrected.
    Another commenter stated that experience has shown that the 
required protection may be best provided by using a current transformer 
and thermal overcurrent relay rather than a thermostat. The commenter 
also stated that this type of protection would not be dependent upon 
control power and would still be able to deenergize the primary of the 
transformer. MSHA agrees with this comment. The final rule is changed 
to allow more flexibility in the use of thermal protection. It permits 
the use of a current transformer and a thermal overcurrent relay to 
provide required overtemperature protection.
    Paragraph (a)(5) of the final rule, like the proposed rule, 
requires high-voltage motor and shearer circuits to be provided with 
instantaneous ground-fault protection set at not more than 0.125-
ampere. This provides highly sensitive and responsive ground-fault 
detection systems, using existing technology, for high-voltage circuits 
supplying electric face equipment. Protective devices are required to 
operate instantaneously, greatly reducing the likelihood of fires and 
shock hazards caused by ground faults. Some commenters suggested that 
the instantaneous ground-fault protection be set at not more than 
0.125-ampere if the full-load current of the circuit does not exceed 
200 amperes and set at not more than 0.200-ampere if the full-load 
current of the circuit exceeds 200 amperes. These commenters pointed 
out that it is very difficult to produce ground-fault current 
transformers that can reliably discriminate between small ground-fault 
currents and larger motor starting currents. They further stated that, 
when the full load current of a circuit exceeds 200 amperes, it is 
reasonable to expect motor starting currents to exceed 2,000 amperes 
and that a small increase in the setting of the ground-fault protection 
is justified for certain high-current circuits. Finally, they stated 
that a 0.200-ampere setting would still be less than 40 percent of the 
maximum ground-fault current. Ground-fault devices are used to detect 
low levels of fault currents during a grounded phase condition. These 
sensitive devices can be influenced by extremely large values of motor 
starting current.
    MSHA has evaluated these comments and determined that there are 
sensitive ground-fault protective devices commercially available that 
have been successfully used to respond to the conditions described by 
the commenters. These devices can safely and reliably operate at 0.125-
amperes or less even on systems having higher motor-starting currents. 
A large number of existing high-voltage longwall systems use grounding 
resistors that limit ground-fault currents to 0.500-amperes. Raising 
the trip value of ground-fault devices protecting motor and shearer 
cables to 0.200-amperes would also have the device set at 40 percent of 
the current rating of the grounding resistor. This setting would be the 
same value as protective devices used on cables extending from power 
centers to motor-starter enclosures. Proper coordination of these 
protective devices with upstream devices may not be achievable if the 
trip setting is raised to 0.200-ampere. For this reason, the provision 
is unchanged from the proposed rule.
    Paragraph (a)(6) of the final rule, like the proposed rule, allows 
time delay settings, not to exceed 0.25 second (15 cycles), of ground-
fault protective devices to provide coordination with the instantaneous 
ground-fault protection of motor and shearer circuits. This provision 
limits the time lapses between actuation of the section power center 
ground-fault protective devices and those located in the motor-starter 
enclosure. Time delay settings allow coordination and selective 
tripping of circuit protective devices. This coordination and selective 
tripping also assures that the entire circuit deenergizes quickly to 
reduce exposure to shock hazards.
    A commenter wanted a time delay of 0.1 second (6 cycles) for 
ground-fault protection for high-voltage motors. The commenter 
described situations where nuisance tripping occurred during starting 
and stopping of the motor and a time delay of 0.1 second would solve 
the problem. MSHA has evaluated this comment and has determined that 
technology is available and currently used by industry to alleviate 
this condition without changing the time delay. Most ground faults 
occur between the motor-starter enclosure and the motors or shearers. 
These ground faults must be removed as quickly as possible. Another 
commenter wanted to add wording to define the total time for ground-
fault protection as 0.4 second (24 cycles) maximum for all devices. 
Most longwall systems now utilize two ground-fault protective devices 
with a time delay of 0.25 second (15 cycles) which provides adequate 
time for selective tripping. Thus, the final rule is unchanged from the 
proposed rule.
    Paragraph (a)(7) of the final rule, like the proposed rule, 
requires an undervoltage protection device that operates on loss of 
voltage to cause and maintain the interruption of power to a circuit. 
The rule reduces the likelihood that miners will be pinned or crushed 
due to the automatic restarting of the equipment. A commenter suggested 
another means of compliance by using a ``momentary start contactor with 
a seal in circuit.'' In response, the rule, unchanged from the proposed 
rule, is performance oriented and permits any undervoltage protection 
provided by a device that operates on loss of voltage. Therefore, any 
voltage sensing device, including the method specified by the 
commenter, that would prevent the automatic reclosing of the circuit 
protective device as specified in paragraph (a) will meet the 
requirements of the final rule.
    Paragraph (b) of the final rule, like the proposed rule, requires a 
single window-type current transformer to encircle the three-phase 
conductors for ground-fault protection. The equipment safety grounding 
conductors are prohibited from being passed through or connected in 
series with ground-fault current transformers. This configuration could 
defeat ground-fault protection and result in hazardous voltage on 
equipment frames. A single window-type current transformer must be used 
to provide the ground-fault protection required by paragraph (a)(4)(i) 
for circuits extending from the section power center to the motor-
starter enclosures. It also requires the same type current transformer 
for ground-fault protection specified in paragraph (a)(5) for:
    (1) High-voltage motor circuits extending from the motor-starter 
enclosures;
    (2) The shearer motor circuits extending from the section power 
center; and
    (3) Motor enclosures.
    Some commenters suggested this provision should allow for 
alternative components if they provide equivalent or improved 
protection. MSHA, however, is unaware of any alternative device that 
provides equivalent

[[Page 10985]]

protection and the commenter did not specify any equivalent devices. 
The use of a single window-type current transformer to encircle only 
the three phase conductors assures that sensitive ground-fault devices 
will be able to detect all ground faults exceeding the setting of the 
device. Detection devices inserted in the ground wire may not detect 
all ground-fault currents and could compromise the integrity of the 
ground circuit. Therefore, paragraph (b) of this section remains as 
proposed.
    Paragraph (c) of the final rule requires a ground-fault test 
circuit for each ground-fault current device. This test circuit must 
inject a current of 50 percent or less of the current rating of the 
grounding resistor to verify that a ground-fault condition causes the 
corresponding circuit-interrupting device to open. This testing 
procedure helps determine if ground-fault current devices function at 
required current levels. It will also test the sensitivity of each 
device to ground-fault currents. The proposed rule required each 
ground-fault current device to be provided with a test circuit that 
would inject a current of 50 percent or less of the current rating of 
the grounding resistor and cause each corresponding circuit-
interrupting device to open. Some commenters suggested that this 
requirement be limited to ground-fault circuit devices required by 
paragraphs (a)(4)(i) and (a)(5) of this section. These commenters also 
suggested that the ground-fault test circuit inject a primary current 
into the current transformer that does not subject the equipment to an 
actual phase-to-ground fault. They pointed out that primary current 
injection tests of the ground-fault devices are safe and effective 
tests for those devices. They further stated that testing of the backup 
ground-fault devices located across the grounding resistor, such as the 
potential transformer and overtemperature relay, would require 
application of an actual phase-to-ground fault and could be hazardous 
to both personnel and equipment. MSHA agrees with the commenters that 
this method of testing is considered to be safe and effective in 
determining whether a device trips at its setting. In response to these 
comments, the final rule modifies the proposed rule, to require each 
ground-fault current device required by paragraphs (a)(4)(i) and (a)(5) 
to have a test circuit that passes a primary current of 50 percent or 
less of the maximum ground-fault current through the current 
transformer and cause the corresponding circuit-interrupting device to 
open.
    Paragraph (d) of Sec. 75.814, like the proposed rule, prohibits the 
use of circuit-interrupting devices that automatically reclose. 
Automatic reclosure of the circuit-interrupting device allows immediate 
reenergization of a circuit that has sustained a fault. Faults occur in 
underground electrical systems as a result of damage from roof falls or 
equipment insulation failure. Under such circumstances, the use of 
automatic reclosing circuit-interrupting devices could create shock and 
fire hazards when a short-circuit or ground-fault condition exists in 
the circuit. There were no comments on this paragraph and it remains as 
proposed.
    The final rule includes an additional paragraph (e) that is 
partially derived from Sec. 75.518-1--Electric equipment and circuits; 
overload and short circuit protection; minimum requirements. This was 
suggested by joint commenters from industry and labor to address 
concerns regarding the use of cables in parallel. The commenters 
suggested that when two or more cables are used to supply power to a 
common connection point (bus), each cable be provided with ground-wire 
monitoring so that all cables are deenergized when the grounding 
conductor becomes severed or open. In support of this suggestion, the 
commenters noted that when two or more cables are connected in 
parallel, shock hazards will exist if one cable has been disconnected 
and the other cable is left energized. MSHA agrees. The Agency has been 
incorporating this additional requirement into petitions for 
modification of Sec. 75.1002 during the last four years. The final rule 
requirement that parallel power cables be installed with ground-wire 
monitor systems addresses this concern. Ground-wire monitoring in power 
cables has been an inherent part of the developing high-voltage 
longwall technology over the last 16 years. In addition, under the 
final rule, parallel circuits installed after the effective date of 
this rule must be protected by a single circuit-interrupting device 
rather than have circuit-interrupting devices operating in parallel 
unless such devices are mechanically and electrically interlocked. This 
is supported by the fact that 30 CFR Sec. 75.518-1 requires overcurrent 
devices to conform to the provisions of the National Electric Code 
which prohibits parallel connections of circuit-interrupting devices.

Section 75.815  Disconnect Devices

    Section 75.815 of the final rule includes requirements pertaining 
to disconnecting devices located in longwall power centers and in 
longwall equipment motor controllers that provide a safe means of 
disconnecting power during the performance of electrical work. It 
includes design and performance requirements pertaining to electrical 
ratings, lockout, grounding, and maintenance requirements pertaining to 
compliance with part 18 of Title 30 CFR. This section was derived, in 
part, from existing Secs. 75.511, 75.520, 75.601, 75.705, and 75.808.
    Paragraph (a) as in the proposed rule, requires a disconnecting 
device in addition to the circuit-interrupting device (required by 
Sec. 75.814) in the power center that supplies power to longwall 
equipment. This disconnecting device provides visual evidence that the 
circuit is deenergized. Either a disconnecting switch or cable coupler 
would suffice to satisfy this requirement. Disconnecting devices in 
power centers facilitate the deenergization process prior to 
performance of electrical work. Figures I-1 and I-2 in Appendix A 
provide guidance for compliance with this requirement. The Agency did 
not receive any comments on this provision and it is unchanged from the 
proposed rule.
    Paragraph (b) of the final rule, like the proposed rule, 
establishes maintenance requirements for disconnecting devices in 
motor-starter enclosures. Section 75.815(b) requires that disconnect 
devices be maintained in accordance with the approval requirements of 
paragraph (f) of Sec. 18.53--High-voltage longwall mining systems. 
Section 18.53(f) requires that the load-side power conductors be 
grounded when the disconnecting device is open. This provision guards 
against the occurrence of electrical accidents by requiring the circuit 
disconnect device to ground the disconnected circuit before work is 
performed on the circuit. The final rule assures that a properly 
maintained safe means of deenergizing longwall circuits and equipment 
is readily available for use during routine operation or in the event 
of an emergency. Additionally, the final rule provides for safe 
deenergization of high-voltage circuits in the motor-starter enclosure, 
or equipment supplied power through the enclosure during testing and 
troubleshooting work. MSHA encourages mine operators to continue using 
additional disconnecting devices that are already installed in many 
existing longwall systems.
    Paragraph (b) requires a caution label on the cover of each starter 
enclosure compartment containing the main disconnecting device. This 
caution label must warn miners against entering the compartment before 
deenergizing the incoming high-voltage circuits to the

[[Page 10986]]

compartment. It warns miners that the line side of the disconnect 
device may be energized when the device is opened and cautions them to 
deenergize incoming power before removing any covers. It also helps to 
assure that miners deenergize power to starter enclosures before 
removing any of the covers. There were no comments received on this 
provision so the final rule is unchanged from the proposed rule. MSHA 
recognizes that the mining industry has taken safeguards by using 
additional caution labels to warn miners of stored energy devices 
(capacitors). We encourage the industry to continue the safety practice 
of using caution statements that warn miners to ground the capacitors 
before performing work on electric circuits.
    Paragraph (c) of the final rule, like the proposed rule, requires 
disconnecting devices to have voltage and current ratings compatible 
with the circuits in which they are used. This requirement ensures safe 
operation of these devices during normal use. The Agency received no 
comments on this provision. It remains the same as the proposed rule.
    Paragraph (d)(1) of the final rule, like the proposed rule, 
requires that disconnecting devices be designed to provide visual 
evidence that all ungrounded power conductors are disconnected when the 
device is open. Visual evidence means the ability to observe the 
physical separation of the control and power conductors without 
removing any covers. There were no comments received on this provision 
and no changes were made to the proposed rule.
    Paragraph (d)(2) of the final rule, like the proposed rule, 
requires that disconnecting devices be equipped to ground all power 
conductors when the device is ``open''. This requirement allows the 
circuit to be properly grounded before any work is performed on the 
electric circuits or equipment. It also allows discharging of any 
existing voltage due to capacitance between the power conductors and 
ground. The Agency did not receive any comments on this provision. It 
remains unchanged from the proposed rule.
    Paragraph (d)(3) is unchanged from the proposed rule. It requires 
each device be equipped to lock the device in the open position. This 
ensures that the circuit being worked on remains deenergized until work 
is completed. There were no comments received in response to this 
provision.
    Paragraph (e) of the final rule, like the proposed rule, requires 
that disconnecting devices, except those installed in explosion-proof 
enclosures, be capable of interrupting load currents without creating 
hazardous conditions. If the device is not designed for full load 
interruption, the device must be installed so that a circuit-
interrupting device will deenergize the incoming power circuit before 
the disconnecting device opens. Use of improperly rated devices could 
result in the destruction of the device and injuries to miners due to 
flash burns or flying parts. The final rule further requires that 
disconnecting devices installed in explosion-proof enclosures be 
maintained in accordance with the approval requirements of 
Sec. 18.53(f)(2)(iv) of part 18. This provision specifies that 
disconnecting devices be designed and installed to cause the current to 
be interrupted automatically prior to the opening of the contacts of 
the device. The Agency did not receive any comments on this provision 
so it remains the same as the proposed rule.
    Some commenters suggested that a new paragraph (f) be added to 
require that any additional disconnecting devices used to deenergize a 
portion of the longwall equipment meet the requirements of paragraphs 
(c), (d), and (e). They stated that it is often necessary to maintain 
power on part of the longwall equipment in order to safely and 
efficiently perform electrical work on another part of the equipment. 
For example, they stated that a disconnecting device for the shearing 
machine circuit will permit electrical work on a deenergized shearing 
machine while maintaining power on the rest of the longwall. Under the 
final rule, individual disconnecting devices, such as cable couplers, 
may be used to isolate individual pieces of equipment for the purpose 
of performing maintenance. The final rule requires that all additional 
disconnecting devices satisfy the requirements of paragraphs c, d, and 
e. Therefore, the Agency believes that an additional provision is not 
necessary.

Section 75.816  Guarding of Cables

    This rule is derived in part from existing Sec. 75.807--
Installation of high-voltage transmission cables and addresses guarding 
of high-voltage cables supplying longwall equipment. Until this rule, 
Sec. 75.807 related to high-voltage cables in areas not in by the last 
open crosscut or not within 150 feet from the pillar workings. In 
addition to the Sec. 75.807 requirements, Sec. 75.816 of this final 
rule requires guarding of high-voltage cables where persons regularly 
work or travel over or under the cables and where the cables leave 
cable handling or support systems in the longwall face areas or are 
within 150 feet of the pillar workings. As provided in Sec. 75.807, 
cables installed six and one half feet or more above the mine floor 
satisfy these requirements by location. Guarding minimizes the 
possibility of miners inadvertently contacting the cables. Also, cable 
guarding must consist of grounded metal or nonconductive flame-
resistant material. High-voltage cables used to supply longwall 
equipment could present shock and fire hazards if the cables are 
damaged or defective.
    Paragraph (a)(1) of the final rule, like the proposed rule, 
requires that cables be guarded where persons regularly work or travel 
over or under the cables. This minimizes accidental contact with 
cables. There were no comments received on this provision and it is 
unchanged from the proposed rule.
    Paragraph (a)(2) of the final rule, like the proposed rule, 
requires guarding where the cables leave cable handling or support 
systems to extend to electric components. This provision prevents 
physical damage from stress and flexing that might cause shock and fire 
hazards. The Agency did not receive any comments on this provision and 
it remains the same as in the proposed rule.
    Paragraph (b) of the final rule requires guarding of high-voltage 
cables to minimize the possibility of inadvertent contact with cables 
and to protect high-voltage cables from physical damage. Guarding must 
be constructed of grounded metal or nonconductive flame-resistant 
material. This standard provides minimum requirements for the physical 
and electrical protective characteristics of the guarding. The proposed 
rule required that guarding prevent miners from contacting high-voltage 
cables.
    One commenter suggested that the provision specifically permit the 
use of either continuous guarding or overlapping sections of guarding. 
According to this commenter, overlapping sections of guarding achieve 
the safety goal of the provision and would reduce time-consuming and 
expensive repairs that could involve thousands of feet of cable to 
repair a small section. In response to this comment, the rule specifies 
the locations where cables are required to be guarded. Under the rule, 
the guarding material must cover the cables and continuous or 
overlapping guarding may be used. When joining sections of metal 
guarding, steps should be taken to assure proper grounding.
    Other commenters suggested that this section require that guarding 
``minimize'' rather than ``prevent'' the possibility of miners 
contacting the cables. They stated that it is not

[[Page 10987]]

practical to design guarding that would prevent miners from contacting 
the cables. This often occurs when miners are attempting to guide or 
train cable into its holding trough when it is loose or falls out. They 
suggested it is possible to design guarding that would ``minimize'' 
contact or ``block access'' to the cable. MSHA agrees with this 
commenter and modified the proposed rule. In response to these 
comments, this revised provision, requires a physical barrier 
consisting of guarding material between the cables and miners to 
minimize inadvertent contact with the cables, and requires mechanical 
protection for the cables. Also, Sec. 75.818 of the final rule 
prohibits intentional contact with cables except for the purpose of 
training (guiding) motor and shearer cables with the use of proper 
protective equipment.

Section 75.817  Cable Support Systems

    This section of the rule addresses handling and support systems of 
high-voltage cables suppling longwall equipment. Under the final rule, 
longwall mining systems must be equipped with cable handling and 
support systems that are constructed, installed, and maintained to 
protect high-voltage cables from damage and to minimize the possibility 
of miners inadvertently contacting the cables. Under the proposed rule, 
these systems were required to prevent miners from contacting high-
voltage cables. High-voltage cables used to supply longwall equipment 
can present shock and fire hazards if the cables become damaged or 
defective. This section of the final rule provides the necessary 
protection to cables and miners by minimizing exposure to damaged or 
defective cables. This section is derived, in part, from existing 
requirements in Sec. 75.807 and addresses new systems developed by the 
mining industry to mechanically handle and support cables. These 
systems are presently used on high-voltage longwall mining systems to 
minimize damage to the cables.
    One commenter suggested that a provision be added to this section 
that allows the installation of guarded high-voltage cables in cable 
handling and support systems where hydraulic hoses and low- and medium-
voltage cables are also installed. In response to this comment, high-
voltage longwall equipment and associated cables are currently required 
by existing Sec. 18.36(b)--Cables between machine components to be 
isolated from hydraulic lines. Also, existing Sec. 75.807 currently 
requires that the high-voltage cables be placed in a manner to prevent 
contact with other low-voltage circuits. Isolation and placement help 
guard against fire and assures protection of electric cables, which 
could be damaged, if hydraulic lines are ruptured or conductor 
insulation fails. Based on MSHA experience, acceptable methods which 
meet Sec. 18.36(b) requirements will be determined during the part 18 
approval process. Guarding of cables by proper isolation and placement 
is an acceptable method to meet this requirement.
    Other commenters suggested that the wording of the rule be changed 
to ``longwall mining equipment shall be provided with cable handling 
and support systems that are constructed, installed, and maintained to 
minimize the possibility of miners contacting the cables and to protect 
the high-voltage cables from damage.'' We agree with the commenters as 
stated in the previous discussion of Sec. 75.816. The final rule 
requires that cable support systems minimize the possibility of 
inadvertent contact instead of preventing contact.

Section 75.818  Use of Insulated Cable Handling Equipment

    This section of the final rule addresses the types of personal 
protective equipment that may be used when it is necessary to handle 
high-voltage longwall cables, the examination for defects or damage 
prior to use, and the intervals at which high-voltage protective 
equipment must be tested. Its purpose is to provide protection against 
electric shock hazards associated with the handling of energized high-
voltage longwall cables. This section is derived, in part, from 
existing requirements in Secs. 75.705-6--Protective clothing; use and 
inspection, 75.705-8--Protective equipment; testing and storage and 
75.812--Movement of high-voltage power centers and portable 
transformers; permit.
    Paragraph (a) of the final rule, like the proposed rule, requires 
that personal protective equipment be used when training or guiding, by 
hand, a high-voltage longwall cable into the cable handling trough when 
the cable inadvertently comes out. Commenters suggested that the list 
of protective equipment be expanded to include facial protection and 
protective clothing, and that the protective equipment also be capable 
of providing protection from a cable explosion. They stated that 
additional protection is needed for persons who handle high-voltage 
longwall cables, since persons have been burned when power conductor 
insulation deteriorates within the cable and the power conductors fault 
or contact each other, causing the cable to explode. MSHA disagrees. 
Shielded-type cables, required by existing regulations, provide the 
necessary protection for miners by limiting or preventing electrical 
arcing and flashover within the cable. This protection occurs as long 
as the cables are used in conjunction with proper mechanical 
protections required under Sec. 75.817, and with proper maintenance of 
electrical protective devices required under Sec. 75.814. Therefore, 
paragraph (a) of this final section remains as proposed.
    Paragraph (b) of the final rule requires high-voltage insulated 
gloves, sleeves, and other insulated personal protective equipment, to 
have a Class 1 (7,500 maximum use volts) or higher rating that has been 
established by a nationally recognized consensus standard. The 
protective equipment must be: (1) Examined prior to each use for signs 
of damage or defects; (2) destroyed or removed from the underground 
area of the mine if found damaged or defective; and (3) electrically 
tested every six months according to a nationally recognized consensus 
standard. This provision protects against electrical shock hazards by 
requiring personal protective equipment to be rated for a maximum use 
voltage and examined before each use to determine if the equipment is 
safe to use. Paragraph (b) of the proposed rule required all personal 
protective equipment to be rated for 20,000 volts; examined before each 
use for visible signs of damage; removed from the underground area of 
the mine when damaged or defective; and electrically tested every six 
months.
    A commenter suggested that this paragraph be modified to allow 
gloves to be rated for a minimum of 5,000 volts and tested every six 
months as described in a nationally recognized consensus standard. The 
Agency is not aware of any recognized consensus standards that rate 
gloves, sleeves, and other personal protective equipment at 5,000 
volts. The commenter also stated that damaged or defective gloves 
should be permitted to be either removed from the underground area of 
the mine or destroyed.
    Another commenter stated that insulated personal protective 
equipment should be electrically tested by the manufacturer in 
accordance with ASTM standards and be rated for at least the maximum 
nominal voltage of the circuit. The commenter also stated that personal 
protective equipment should be examined before each use for visible 
signs of damage or defects and be electrically tested at least every 
six months or when there is any sign of excessive wear. This commenter 
stated that the visible and electrical tests

[[Page 10988]]

should be conducted in accordance with American Society for Testing and 
Materials (ASTM) standards.
    In response to the commenters' concerns, we agree that safety would 
be enhanced by adopting the ASTM standard. We have revised paragraph 
(b) of the proposed rule. The final rule requires insulated protective 
equipment, including high-voltage gloves and sleeves, to be rated a 
Class 1 or higher (maximum use voltage of 7,500 volts). Paragraph 
(b)(1) requires that this equipment be examined before each use for 
visible signs of damage or defects. This section requires users of 
protective equipment to examine it for hazardous conditions, including 
excessive wear. For example, a method commonly used to detect damage in 
insulating gloves is to test the rubber gloves 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 by feeling escaping air against the face.
    In response to commenters, the Agency has revised paragraph (b) in 
the final rule to allow defective personal protective equipment to be 
destroyed or removed from the mine. The Agency agrees with the 
commenter that destroying this equipment when it becomes defective is 
as effective as removing it from the underground mine.
    MSHA also received comments suggesting that insulating protective 
equipment be tested every six months in accordance with nationally 
recognized standards. The Agency agrees with this commenter and has 
revised paragraph (b) to require that all insulated handling equipment 
for use with high-voltage longwall cables be electrically tested every 
six months in accordance with a nationally recognized consensus 
standard contained in the ASTM F496-97, ``Standard Specification for 
In-Service Care of Insulating Gloves and Sleeves.'' The purpose of 
these formal testing procedures for high-voltage cable handling 
equipment is to provide necessary safety protections for miners and 
ensure that unknown equipment defects will be detected before they are 
a hazard to miners.

Section 75.819  Motor-Starter Enclosures; Barriers and Interlocks

    Section 75.819 of the final rule, like the proposed rule, requires 
separation by location, partitions, or barriers of low- and medium-
voltage circuits from high-voltage circuits in motor-starter enclosures 
and requires cover interlock switches to be installed on the cover of 
any motor-starter compartment containing high-voltage components. The 
compartment separations and interlock switches must be maintained in 
accordance with paragraphs (a) and (b) of Sec. 18.53--High-voltage 
longwall mining systems. The purpose of Sec. 75.819 is to help guard 
against miners coming in contact with energized internal components of 
high-voltage electric equipment through proper maintenance of safety 
devices that assure deenergization when any cover that provides access 
to energized high-voltage components is removed. Compartment separation 
also helps assure that persons are not exposed to adjacent energized 
high-voltage components or circuits after gaining access to 
compartments containing control, communication, or other low- and 
medium-voltage circuits.
    This provision provides automatic protection for miners who may 
inadvertently remove a cover exposing energized high-voltage circuits 
should the wrong circuit be disconnected. There were no comments 
received on this section of the proposed rule and it remains as 
proposed.

Section 75.820  Electrical Work; Troubleshooting and Testing

    Section 75.820 is directed at protecting miners while they are 
performing electrical work, including troubleshooting and testing, and 
the removal of belt structure. This section is derived, in part, from 
existing Secs. 75.509--Electric power circuit and electric equipment; 
deenergization, 75.511--Low-, medium-, or high-voltage distribution 
circuits and equipment; repair, and 75.705--Work on high-voltage lines; 
deenergizing and grounding and addresses requirements for performing 
work on all circuits and equipment associated with high-voltage 
longwalls. This section applies to all low-, medium-, and high-voltage 
circuits and equipment associated with high-voltage longwalls. The 
requirements are similar to those in existing Secs. 75.509 and 75.511 
for work on electric circuits and equipment generally, except with 
additional requirements applicable to high-voltage longwall 
installations. These requirements include personnel qualifications and 
safe work procedures, including safety equipment when troubleshooting 
and testing, and methods to guard against contact with energized high-
voltage cables during the installation and/or removal of belt 
structure(s). The final rule for Sec. 75.820 is identical to the 
proposed rule except for changes to Sec. 75.820(a), which is revised 
based on a recent Federal Mine Safety and Health Review Commission 
decision and Secs. 75.820(d)(3) and 75.820(f) which MSHA revised due to 
comments. The revisions address: (1) The fact that persons qualified 
under Sec. 75.153--Electrical work; qualified person must be able to 
perform electrical work on all circuits and equipment; (2) The type of 
gloves that must be worn by persons performing troubleshooting and 
testing; and (3) The methods used to guard against contact with a high-
voltage cable during installation and/or removal of belt structure.
    Paragraph (a) of the final rule requires that electrical work on 
all circuits and equipment associated with high-voltage longwalls be 
performed only by persons qualified, in accordance with Sec. 75.153, to 
perform electrical work on all circuits and equipment, not just high-
voltage circuits and equipment. This change is consistent with the 
recent Federal Mine Safety and Health Review Commission decision, 
Secretary of Labor v. Black Mesa Pipeline, Inc. 22 FMSHRC 708, 715 
(June 30, 2000). That decision concluded that Sec. 75.153 requires that 
a ``person qualified'' be knowledgeable of high-, medium-, and low-
voltage circuits and equipment. Therefore, for clarification purposes, 
the language of this final rule has been modified to conform with this 
decision and the plain meaning of Sec. 75.153. This requires that a 
person qualified to work on electrical circuits be knowledgeable of 
low-, medium- and high-voltage circuits. The Agency currently requires 
that qualification in all voltages be obtained before a person can 
become qualified under Sec. 75.153. The requirement that persons 
performing electrical work be qualified for all voltages assures that 
persons performing work on low- and medium-voltage circuits are 
qualified to identify hazards that may exist on high-voltage circuits 
in close proximity of their work.
    Some commenters suggested that paragraph (a) state that electrical 
work on all high-voltage circuits and any enclosure containing high-
voltage components shall be performed only by persons qualified under 
Sec. 75.153 to perform electrical work only on high-voltage circuits 
and equipment. These commenters indicated that the proposed rule would 
not permit persons qualified under Sec. 75.153 to perform electrical 
work only on low- and/or medium-voltage circuits or equipment or 
perform any electrical work on circuits or equipment associated with a 
high-voltage longwall. The commenters further indicated that certain 
subsystems of the longwall are completely isolated from high-voltage 
circuits and equipment such as: lighting systems, communication 
systems, shield

[[Page 10989]]

control systems, hydraulic pump control systems, battery chargers, air 
compressors, and rock dusters. However, because many low- and medium-
voltage circuits associated with high-voltage longwalls are in close 
proximity to the high-voltage circuits, MSHA believes it is important 
that anyone performing electrical work on the high-voltage longwall be 
knowledgeable about low-, medium- and high-voltage circuits. And, as 
noted above, a person qualified under Sec. 75.153 must be knowledgeable 
of all voltage circuits.
    Since all the circuits cannot be totally isolated, it is important 
that qualified persons working on the circuits of lower voltages be 
aware of the hazards of high-voltage circuits. Another commenter 
inquired as to what the high-voltage qualification requirements were 
and suggested that MSHA ensure that appropriate training is defined and 
required. MSHA's existing standard in Sec. 75.511--Low-, medium-, or 
high-voltage distribution circuits and equipment; repair requires that 
only persons qualified in low-, medium- and high-voltages perform high-
voltage work, and Sec. 75.153 sets forth the procedures for their 
qualification. Additionally, existing Sec. 75.160--Training programs 
requires an MSHA approved plan for retraining qualified persons. 
Another commenter requested that wording be added to allow anyone to 
perform high-voltage work under the supervision of a qualified person. 
Due to the hazards previously described, only qualified electricians 
perform high-voltage work. Therefore, except for the clarifications 
noted above, paragraph (a) of this section remains as proposed.
    Generally, paragraphs (b)(1) through (b)(4) of Sec. 75.820, like 
the proposed rule, require safety precautions to be taken by qualified 
electricians prior to performing electrical work. The qualified 
electrician is responsible for assuring that the electrical circuit is 
properly deenergized, that the contacts of the circuit disconnecting 
device are open, and that the disconnecting device is locked out with a 
padlock and tagged. These precautions assure that the affected circuit 
has been properly deenergized and disconnected so that persons 
performing work are not exposed to shock, electrocution, or burn 
hazards. Without taking precautions, such as properly locking out and 
tagging the affected circuit, qualified electricians would be exposed 
to shock and electrocution risks if someone were to inadvertently 
reenergize the circuit.
    Paragraph (b)(1) of the final rule specifically requires that a 
qualified person deenergize the circuit or equipment with a circuit-
interrupting device. There were no comments on paragraph (b)(1) of the 
proposed rule. This paragraph of the section remains as proposed.
    Paragraph (b)(2) of the final rule requires that a qualified person 
open the disconnecting device when performing work on circuits and 
equipment, and if high-voltage, ground the circuits. Opening the 
disconnect device deenergizes the circuit which, along with grounding, 
protects the person working on the circuit from shock and electrocution 
hazards. A commenter stated that in addition to grounding the circuit 
prior to work being performed, that grounding hot sticks (a collapsible 
non-conductive pole used to de-energize electrical circuits) rated at 
4,160 volts should be available at each power center and a proximity 
tester should be used by the qualified electrician to determine that 
the circuit is deenergized. In response to this comment, Sec. 75.815(b) 
of the final rule requires that the disconnecting devices be maintained 
in accordance with the approval requirements of paragraph (f) of 
Sec. 18.53. Section 18.53(f) in turn requires that the disconnecting 
devices ground the circuit when ``open.'' In addition, the requirement 
in paragraph (b)(3) of Sec. 75.820 places responsibility on each 
qualified person to lock out the disconnecting device for the high-
voltage circuit prior to performing work. Therefore, MSHA concludes 
that equipping power centers with grounding hot sticks, clamps, and 
proximity testers, as suggested by the commenter, is not necessary. 
Therefore, paragraph (b)(2) of this section remains as proposed.
    Paragraph (b)(3) of the final rule, like the proposed rule, 
requires that disconnecting devices be locked with an individual 
padlock by each person performing work. Individual padlocks, removable 
only by the persons who installed them, place responsibility on the 
persons performing work to assure their personal safety. This should 
prevent accidental reenergization of equipment or circuits before all 
persons have completed work. The danger and accident history of 
reenergization of circuits before work is completed require such 
measures for the protection of miners against electrocution or electric 
shock. A commenter suggested that the section be reworded to permit the 
oncoming worker to install his/her lock, and the departing worker to 
remove his/her lock at the change of shifts. Another commenter 
suggested that MSHA recognize that service or maintenance in many cases 
is performed by a new crew or group of people and that a group lockout 
procedure be allowed. This commenter suggested that primary 
responsibility can be vested with an authorized employee when more than 
one group is working on the equipment, so that an authorized person 
from each group may lockout the equipment. A review conducted by the 
Agency in 1999 revealed that during the period 1970 to 1999, a total of 
145 fatal accidents occurred by miners contacting energized circuits. 
Data further revealed that during a five year period between 1994 and 
1999, a total of nine fatal accidents were related to failure to 
lockout disconnecting devices. The review also revealed that deaths and 
injuries had also occurred when equipment was energized before all 
persons had completed their work. Furthermore, the National Safety 
Council in Data Sheet 237 Revision B, Methods of Locking Out Electrical 
Switches (1971), recommends that individual, not group, type lockout 
procedures be used. This publication is available in the rulemaking 
record. Consistent with Agency experience and safety recommendations, 
the final rule requires individual lockout rather than group lockout. 
MSHA is confident that this system provides the necessary safety 
protection because persons assigned to place and remove their own locks 
are more cognizant of and responsible for their own security, and more 
likely to take the steps necessary to assure proper deenergization. 
This also reduces the risk of error due to lack of communication or 
inadvertent reenergization. For these reasons, the paragraph remains 
unchanged from the proposed rule.
    Paragraph (b)(4) of the final rule, like the proposed rule, 
requires tags used on deenergized circuits and equipment to identify 
each person performing work and the circuit or equipment on which work 
is being performed. There were no comments on this paragraph of the 
proposed rule and it remains as proposed.
    Paragraph (c) requires, like the proposed rule, that only the 
persons who install a padlock and tag be permitted to remove them. This 
provision also provides for an exception where an operator could 
authorize someone else to remove the lock and tag if the person who 
installed them is unavailable at the mine. Such authorized person is 
required to be qualified to perform electrical work. Additionally, the 
person who had originally installed the lock and tag must be informed 
of the lock removal before resuming work on the circuit or equipment. A 
commenter stated that in the absence of the person who installed

[[Page 10990]]

the lock, the mine operator may designate a qualified electrician to 
remove the lock after it has been determined that all other affected 
persons are not exposed to a hazard. Paragraph (c) of the final rule 
requires locks to be removed by the person who installed them or by 
qualified persons authorized by the operator, if that person is 
unavailable at the mine.
    Paragraph (d) of the final rule requires that certain safety 
procedures be followed when troubleshooting and testing energized 
circuits. This includes limiting troubleshooting and testing of 
energized circuits only to low- and medium-voltage systems. In 
addition, only qualified electricians wearing properly insulated rubber 
gloves are permitted to perform this work and only for the purpose of 
determining voltages and currents. This provision recognizes that, in 
some instances, it is necessary for circuits or equipment to remain 
energized for troubleshooting and testing. For example, in order to 
understand the nature of problems within a circuit, it may be necessary 
to take voltage or current readings while the circuit is energized.
    Paragraph (d)(1) of the final rule, like the proposed rule, limits 
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, the particular 
skills and training of a qualified electrician are necessary for 
performance of these tasks. Troubleshooting and testing is limited to 
low- and medium-voltage energized circuits, primarily due to insulation 
ratings of available troubleshooting and testing equipment. Insulation 
ratings on equipment commonly used to troubleshoot and test in 
underground mines are insufficient to protect persons if such equipment 
is used to troubleshoot and test high-voltage circuits.
    A commenter suggested that troubleshooting of energized circuits 
ranging from 120 to 1,000 volts (low to medium voltage) should be 
prohibited. This commenter indicated that the industry has already 
demonstrated that high-voltage longwalls can be installed, 
commissioned, and maintained without maintenance personnel being 
exposed to any voltage higher than 120 volts. The commenter further 
stated that if multiple utilization voltages are required in the same 
compartment, then each supply should have a disconnect device, and 
cover switches should be arranged to trip circuit-interrupting devices 
to cut off both voltages. Some high-voltage longwalls are designed with 
equipment supplied from low- and medium-voltage as well as high 
voltage. These hybrid-type longwall systems include both high-voltage 
and low- and medium-voltage equipment. This provision allows 
troubleshooting and testing of low- and medium-voltage circuits 
associated with these hybrid longwalls. Based on Agency experience with 
petitions for modification allowing such testing, troubleshooting, and 
testing of low- and medium-voltage circuits can be safely performed 
with proper test instruments, and with use of protective gloves that 
are commercially available. Therefore, paragraph (d)(1) of this section 
remains as proposed.
    Paragraph (d)(2) of the final rule permits troubleshooting and 
testing of energized circuits only for the purpose of determining 
voltages and currents (amperes). Some commenters suggested that 
paragraph (d)(2) be changed to allow troubleshooting and testing to 
determine waveform or other electrical diagnostic testing as well as 
voltages and currents. The final rule, as written, is responsive to the 
commenter's suggestion because evaluation of waveform or diagnostic 
testing is normally considered to be a method of measuring voltage and 
current. Paragraph (d)(2) of this section remains as proposed.
    Paragraph (d)(3) of the final rule requires that troubleshooting 
and testing of energized circuits be performed by persons qualified 
under Sec. 75.153 who wear protective gloves when the voltage of the 
circuit exceeds 40 volts. This should prevent accidents related to 
contact with energized circuits while troubleshooting and testing. 
These gloves will provide the insulation protection necessary if a 
miner has inadvertent contact with energized circuits during 
troubleshooting and testing. A commenter stated that the circuit is 
designed to permit troubleshooting of 120-volt alternating current 
(VAC) control power. During this period, high voltage is not present 
while the normal/test auxiliary switch is in the ``test'' position and 
the incoming high-voltage disconnect is in the ``open/grounded'' 
position. This commenter suggested that gloves be rated for 120 VAC 
rather than the nominal voltage of the circuit. The Agency is not aware 
of any gloves rated for less than 1,000 volts. The rating of gloves is 
determined commercially through formal testing procedures established 
by national standards.
    Another commenter suggested that this paragraph be changed to 
permit the use of dry work gloves when troubleshooting low- and medium-
voltage circuits and to permit troubleshooting of high-voltage 
circuits. The commenter added that wearing rubber gloves should be 
required when working with high-voltage circuits; however, requiring 
that rubber gloves be worn when troubleshooting low- and medium-voltage 
circuits would diminish safety. In response to these comments, MSHA 
believes that rubber gloves do not permit sufficient dexterity, as do 
dry cloth gloves, for the safe troubleshooting of low- and medium-
voltage circuits. For example, an ohm meter has small controls which 
are difficult to operate while wearing rubber gloves and the small 
metal probes used with the ohm meter are hard to pick up while wearing 
rubber gloves. A serious accident could result if probes were 
improperly placed in an energized circuit or dropped in close proximity 
to voltages up to 995 volts. In contrast, dry work gloves allow for 
manual dexterity while providing adequate protection. The commenter 
specified that his company has safely used dry work gloves when 
troubleshooting low- and medium-voltage circuits for 15 years. The 
commenter further stated that proposed Sec. 75.820(d) would conflict 
with existing Sec. 75.509--Electric power circuit and electric 
equipment; deenergization in two respects. The first is that 
Sec. 75.509 permits troubleshooting of high-voltage circuits, as well 
as low- and medium-voltage circuits. In contrast, proposed 
Sec. 75.820(d)(1) would permit troubleshooting only on low- and medium-
voltage circuits. The second is that proposed Sec. 75.820 conflicts 
with MSHA's interpretation of Sec. 75.509 concerning situations where 
insulated rubber gloves are required. MSHA's Program Policy Manual 
states:

    Work gloves in good condition are acceptable for troubleshooting 
or testing energized low-or medium-voltage circuits or equipment. 
High-voltage gloves, rated at least for the voltage of the circuit, 
are required for troubleshooting or testing of energized high-
voltage circuits or in compartments containing exposed energized 
high-voltage circuits. (This portion has been corrected by MSHA 
Program Policy Update V-15.)

The commenter further stated that in order to be consistent with 
Sec. 75.509, as well as prudent mining practices, proposed 
Sec. 75.820(d) should be changed to permit both troubleshooting of 
high-voltage circuits and use of dry work gloves for troubleshooting 
low- and medium-voltage circuits.
    In response the Agency states that existing Sec. 75.705--Work on 
high-voltage lines; deenergizing and grounding specifically applies to 
high-voltage circuits out from (outby) the longwall mining faces or 
pillar workings. Section

[[Page 10991]]

75.705 specifically prohibits work on high-voltage lines underground in 
relation to troubleshooting and testing of high-voltage circuits. 
Section 75.509 generally applies to all electrical circuits and is less 
restrictive. This final rule specifically applies to high-voltage 
circuits on longwalls and is consistent with the safety requirements of 
existing Sec. 75.705.
    Based on Agency data and experience, it is our view that attempts 
to troubleshoot and test energized high-voltage circuits using standard 
test equipment, such as volt-ohm-meters, commonly used on low- and 
medium-voltage circuits, is extremely hazardous. MSHA prohibits 
troubleshooting and testing of energized high-voltage circuits and 
equipment. The use of hand-held proximity testers to determine 
shielding continuity and energized circuits is allowed under this 
regulation. Troubleshooting and testing routinely involves the use of 
portable test instruments equipped with attached leads and metal probes 
used to move from point to point in a circuit for the purpose of 
determining voltage and/or current readings needed to target problem 
areas. Insulation ratings on equipment commonly used to troubleshoot 
and test are insufficient to protect persons if this equipment is used 
on high-voltage circuits. The commenter stated that the MSHA program 
policy manual permitted troubleshooting and testing of energized high-
voltage circuits. After review, MSHA determined that this policy was 
inadvertently drafted in error and specifically conflicts with 
mandatory safety standard Sec. 75.705. The error was corrected in MSHA 
Program Policy Update V-15. The printed-in-error version was never 
officially considered or enforced as MSHA policy.
    Other commenters suggested--(1) that gloves not be required under 
the standard when the maximum circuit voltage does not exceed 40 volts; 
(2) that dry work gloves in good condition be required when the maximum 
circuit voltage does not exceed 150 volts or the circuit voltage 
exceeds 150 volts but is intrinsically safe; and (3) that insulating 
gloves, with protective coverings designed to prevent physical damage 
to the insulating material, be required when the maximum circuit 
voltage exceeds 150 volts and the circuit is not intrinsically safe.
    MSHA agrees with some of the commenters' suggestions and has 
written the final rule to reflect these changes. The final rule 
requires the use of protective gloves when troubleshooting and testing 
circuits having voltages that exceed 40 volts. Based on MSHA electrical 
accident information and experience, 40 volts is the lowest voltage 
level range at which shock hazards are minimized. Other mandatory 
safety standards, such as Secs. 77.515--Bare signal or control wires; 
voltage, 75.901--Protection of low- and medium-voltage three-phase 
circuits used underground, 75.902--Low- and medium-voltage ground check 
monitor circuits, and 77.902-1--Fail safe ground check circuits; 
maximum voltage, use 40 volts as a minimum safety voltage range level. 
Section 18.50--Protection against external arcs and sparks also uses 40 
volts as a minimum voltage range level for shock hazard protection 
guidelines for electrical equipment frames. Dry work gloves, in good 
condition (free of holes, etc.) will be permitted on circuits where the 
voltage does not exceed 120 volts nominal and on circuits where the 
voltage exceeds 120 volts nominal but is intrinsically safe. The normal 
control circuit nominal voltage value is 120 volts for mining 
equipment. Section 75.1720--Protective clothing, requirements and MSHA 
policy allow miners to use dry gloves when working on circuits up to 
1000 volts. Rubber insulating gloves rated for at least the nominal 
voltage of the circuit and equipped with leather protectors will be 
required to be used on circuits where the voltage exceeds 120 volts 
nominal but is not intrinsically safe. (See paragraphs (b)(3) and 
(b)(4)). Mine 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 at this time. The 1,000 volt rated gloves can be 
used on each of these circuits and, in fact, offer increased protection 
for troubleshooting and testing on circuits exceeding 120 volts.
    MSHA's fatality data show that at least six fatalities have 
occurred since 1970 due to miners' contact with energized circuits 
while troubleshooting and testing. The provisions of Sec. 75.820 
address electrocution and shock hazards associated with troubleshooting 
and testing of the low- and medium-voltage portions of high-voltage 
longwalls and provide additional protection for persons performing work 
on these circuits.
    Commenters suggested that the proposed rule be expanded to include 
facial protection, and protective clothing to minimize the risk of 
injury in case of a short circuit during troubleshooting and testing of 
an energized circuit. In support of this suggestion, commenters stated 
that these additional requirements were needed to protect persons from 
an electrical explosion, an electrical flash, and from flying debris. 
Commenters suggested that injuries could be minimized if protective 
clothing, such as a leather vest instead of polyester, was worn, as 
clothing made of material that melts could compound an injury.
    In response, the Agency concludes that when mine operators and 
miners comply with the provisions of this final high-voltage rule, 
including proper testing, examination, and maintenance of circuits and 
equipment, and safe procedures during troubleshooting and testing, 
hazards such as flying debris, electrical arcing, and flashover can be 
avoided. Electrical arcing during troubleshooting and testing is 
normally due to either misapplication or misuse of test equipment. In 
some cases, electrical hazards may occur as a result of circuit 
insulation failure while troubleshooting. Under the final rule, only 
qualified individuals must be assigned to perform troubleshooting and 
testing. Further, they must perform thorough examinations, tests, and 
maintenance of circuits and equipment to help guard against the 
occurrence of injury due to electrical arcing caused by failure of 
insulation.
    Paragraph (d)(4) of the final rule requires that rubber insulated 
gloves, when required, be rated at least for the nominal voltage of the 
circuit. This requirement was contained in paragraph (d)(3) of the 
proposed rule. Comments pertaining to this proposed rule are addressed 
above. The language of this provision remains the same as the proposed, 
but it is renumbered.
    Paragraph (e) of the final rule, like the proposed rule, requires 
deenergization of high-voltage circuits contained in a compartment with 
low-or medium-voltage circuits, in order to troubleshoot or test the 
low-or medium-voltage circuits. Deenergizing, grounding, and locking 
out and tagging the high-voltage circuit provides protection against 
the danger of accidental contact with the high-voltage circuits while 
troubleshooting and testing low- and medium-voltage circuits. Some 
commenters suggested that high-voltage circuits should never be located 
in the same compartment with low- and medium-voltage circuits in order 
to prevent persons from contacting high-voltage circuits while testing 
or working on low- and medium-voltage circuits. In response to this 
comment, electrical closing of high-voltage contactors contained in 
motor-starter enclosures requires low-voltage magnetic components that 
are a part of the contactors. Therefore, sometimes it is necessary, to 
have both high voltage in

[[Page 10992]]

the form of a power circuit and low voltage in the form of a control 
circuit in the same compartment(s) of the motor-starter enclosures. In 
addition, compartments of motor-starter enclosures that house high-
voltage disconnect switches may also contain low-and/or medium-voltage 
control and lighting transformers. The deenergization and lockout 
requirements under the new standard address the safety concerns 
associated with working near multiple voltage circuits. Therefore, the 
Agency concludes that paragraph (e) of this section should remain as 
proposed.
    Paragraph (f) of the final rule requires that high-voltage cables 
located in conveyor belt entries be deenergized, guarded, or isolated 
by elevation prior to the installation or removal of the conveyor belt 
structure. The proposed rule required that the cables be deenergized 
prior to the removal of the structure. Other commenters suggested that 
the deenergization requirement should apply to the installation, as 
well as the removal, of conveyor belt structures. These commenters 
pointed out that the same type of work is performed during belt 
installation as during removal. The Agency agrees with these commenters 
and has concluded that the final rule should apply to advancing as well 
as retreating longwall systems. Therefore, the requirement has been 
changed to apply to installation as well as removal of conveyor belt 
structures. Contact with or damage to energized cables while installing 
or removing conveyor belt structures could cause risks of fire and 
electrocution to miners. The final rule addresses these dangers by 
requiring either deenergization, guarding, or proper location of the 
cables before installing or removing belt structures.
    Commenters suggested that deenergizing the high-voltage cable for 
removal of the belt conveyor structure is often impractical and that an 
alternative would be to guard the cable from direct contact with the 
belt conveyor structure during removal. Reasons given for this 
alternative were: (1) Many of the routine jobs performed along the 
longwall face cannot be performed with the power off (such as 
repositioning of the longwall shearer, moving the shields 
electronically and moving the face conveyor, as well as equipment 
servicing and welding operations that typically contribute to the 
normal safe and efficient operation of the longwall) and (2) Methane 
monitors, face lighting, and on-board shield diagnostics would lose 
power if they receive electrical power through the high-voltage system 
that feeds the face equipment. In addition, the commenter pointed out 
that belt structure removal occurs 2 or 3 times a shift, taking 15 to 
30 minutes each time. Other commenters suggested that this provision be 
deleted, since proper guarding is required by Sec. 75.816. These 
commenters suggested that the requirement would result in deenergizing 
cables even if work is being done 10,000 feet from the cables. Another 
commenter suggested that this requirement should be waived if the high-
voltage cable is installed on monorail because personnel are safely 
protected by the location of the cable.
    Other reasons given for deleting the deenergization requirement 
were: (1) It would be less safe for miners, as it would result in 
deenergization of several longwall safety devices such as the face and 
equipment illumination system; (2) It would result in an undue burden 
for operators due to the time required to travel to and from the power 
center in order to deenergize the cable; (3) It would cause undue 
stress, wear and tear on electrical breakers, components, and cables 
due to frequent energizing and deenergizing; and (4) It would prevent 
most maintenance, service and support functions from being performed 
while the cables were deenergized. The commenter also pointed out that 
the occurrence of high-voltage cable faults is infrequent and the 
commenter has no experience of faults resulting in fire or causing 
shocks to miners. This commenter further stated that currently required 
circuit breakers and ground-fault systems provide adequate fault 
protection and that backup protection is provided by a ``Post 
Gulliver'' ground-fault system at the commenter's operation. Another 
commenter suggested that this requirement should only apply to cables 
which are not guarded and which are located in conveyor belt entries 
less than three feet away from the conveyor belt structure.
    Another commenter suggested that the requirement should not apply 
where the mine operator can demonstrate that the seam height provides 
ample clearance of at least 6.5 feet or other methods are used to 
prevent any possible mechanical damage to high-voltage cables which may 
occur during removal of conveyor belt structures. Another commenter 
indicated that the phrasing of the proposed rule led the commenter to 
believe that MSHA was referring to the complete removal of the conveyor 
belt structure (as would be the case for an advancing longwall). This 
commenter indicated that operators are concerned about application of 
the rule to the more common retreating longwall situation where it is 
part of the routine work to frequently remove sections of conveyor 
structure. This commenter indicated that procedures have been developed 
to ensure that this work can be done without risk of high-voltage 
cables creating a hazard.
    In response to these commenters, the Agency has changed the 
language of the proposed rule. The final rule allows guarding or 
protection by elevation as another means of protecting cables from 
damage and to minimize danger of contact with energized cables. Proper 
guarding of cables in accordance with Sec. 75.816 or protection 
afforded by proper elevation would minimize miner contact with cables 
and minimize damage to the cables. The Agency agrees that there are 
safety advantages in leaving the high-voltage cable energized if the 
cable is properly protected during belt structure installation and 
removal. Examples of safety equipment that would remain energized are 
methane monitors and illumination systems.

Section 75.821  Testing, Examination, and Maintenance

    Section 75.821 of the final rule requires that a person, qualified 
to perform electrical work, test and examine equipment and circuits to 
detect and correct conditions that could lead to an accident and 
injury. The section requires the qualified person to verify by 
signature and date that the tests and examinations have been completed. 
This record will include any unsafe conditions and corrective actions 
taken. The section further requires that the records be kept and made 
available for at least one year. This section was derived, in part, 
from existing Secs. 75.512--Electric equipment; examination, testing 
and maintenance, 75.512-2--Frequency of examinations, 75.800-3--
Testing, examination and maintenance of circuit breakers; procedures, 
and 75.800-4--Testing, examination, and maintenance of circuit 
breakers; record which generally apply to electrical equipment 
underground. This section applies to high-voltage equipment on the 
longwall face or within 150 feet of the pillar workings.
    Paragraph (a) of Sec. 75.821 requires that persons, qualified in 
accordance with existing Sec. 75.153--Electrical work; qualified 
person, test and examine high-voltage longwall equipment and circuits 
to protect miners from electrical or operational hazardous that may 
exist. As noted under the Sec. 75.820 discussion, based on the recent 
Federal Mine Safety and Health Review Commission Black Mesa decision 
(22 FMSHRC 708, 715; June 30, 2000), Sec. 75.153 requires that a 
`person qualified' be knowledgeable of

[[Page 10993]]

high-, medium-, and low-voltage circuits and equipment. Consistent with 
this decision and for clarification purposes, the language of paragraph 
(a) has been modified in the same fashion as in Sec. 75.820(a) to 
conform with the ruling under this decision and the plain meaning of 
Sec. 75.153. Thus, under this paragraph as revised, a person must be 
qualified under Sec. 75.153 to perform electrical work on ``all'' 
circuits and equipment, not just high-voltage circuits. Testing and 
examining high-voltage longwall equipment and circuits allows qualified 
persons to determine that the electrical protection, equipment 
grounding, permissibility, cable insulation, and control devices are 
properly maintained to prevent fire, electric shock, ignition or 
operational hazards from existing on the equipment. Keeping equipment 
free from these hazards is assured by the training and expertise of 
qualified electricians. Regular testing and examination of high-voltage 
equipment used in face areas assures that hazardous conditions are 
discovered and corrected before they can cause injuries to miners. The 
standard requires examinations and tests of high-voltage longwall 
equipment at least once every 7 days.
    Examinations and tests include activating the ground-fault test 
circuit which is required by Sec. 75.814(c) of this final rule. The 
standard assures that problems which arise during normal use of mining 
equipment will be identified and corrected, so that miners are not 
exposed to hazards. Activating the ground-fault test circuit will 
identify any damage or defects in the ground-fault circuit and 
therefore protect miners from being exposed to energized longwall 
equipment frames.
    A commenter stated that 30 CFR part 75 requires mine operators to 
conduct a multitude of tests in the underground environment. The 
commenter further stated that these tests are normally conducted on a 
``daily,'' ``weekly,'' or ``monthly'' basis, and that the proposed rule 
is confusing and can present a problem for those operations working 
under nontraditional schedules. The commenter recommended that for 
clarity and consistency, the phrase ``once every 7 days'' be removed 
and the word ``weekly'' be substituted. In response to this comment, 
circuits and equipment used in conjunction with high-voltage longwalls 
are frequently being moved and subjected to heavy use, increasing the 
likelihood of wear and breakdown. Because of this, it is extremely 
important that defects in circuits and equipment be detected as quickly 
as possible and repaired before the occurrence of related accidents and 
injuries. The Agency considers it very important that the required 
examinations and tests be conducted as frequently as possible from the 
standpoint of safety and practicability, and that an examination at 
least once every seven days rather than weekly provides this assurance. 
A requirement for a weekly examination can result in the equipment not 
being examined for as long as 13-14 days. In addition, the seven-day 
requirement is consistent with similar type requirements contained in 
regulations promulgated by the Agency pertaining to ventilation under 
Secs. 75.312(b)(1)(ii)--Main mine fan examinations and records and 
75.364(a)--Weekly examination. Another commenter suggested that the 
proposed provision was too vague and in order to eliminate confusion, 
submitted the following examination requirements: (1) Actuate each 
ground-fault test circuit required by Sec. 75.814(c); (2) Examine the 
cable guarding and handling system to ensure that they are properly 
installed and protecting the cables; (3) Determine that explosion-proof 
components are maintained in permissible condition; (4) Actuate the 
emergency stop button and verify that the corresponding circuit-
interrupting device opens; and (5) Verify that the face communication 
system is operational. Another commenter suggested that the proposed 
examination requirements were so comprehensive that it would take a 
skilled person two days and that the more limited examination suggested 
by the previous commenter would cover the essential safety aspects.
    In response to the comments regarding adoption of less time-
consuming examination requirements, the complex high-voltage longwall 
mining system contains numerous cables, conductors, and pieces of 
equipment that require time-consuming examinations to assure safe 
operating conditions. Although proper circuit and equipment maintenance 
requires both visual and physical examinations, most examinations are 
visual. In addition, testing of circuits and equipment routinely 
includes activating available test switches to verify proper operation 
and causes the protective devices to open. High-voltage longwall 
equipment contains circuit protective devices that are mounted in 
heavily constructed explosion-proof enclosures containing large bolted 
covers and cables that are protected by heavily constructed guarding. 
The proposed rule required, in part, that a determination be made that 
protective devices, in some cases contained within these enclosures, 
and cables protected by the described guarding, be inspected to assure 
proper maintenance. The Agency believes that verification of proper 
maintenance regarding these items would not require, in all cases, 
removal of the equipment covers and cable guards in order to make this 
determination. Some protective device settings do not change, so 
frequent removal of covers to gain access for inspection serves no 
useful purpose and reduces safety if covers are not properly replaced. 
Removing and replacing guards that are installed to provide mechanical 
protection for cables, without good reason, could likewise result in an 
unsafe condition if not properly replaced.
    Since 1970, Title 30 CFR has contained an examination, test, and 
maintenance requirement for electric equipment that is more basic than 
Sec. 75.821. The Agency has been asked on several occasions to describe 
the required extent of proper examination of circuits and equipment. 
Since there are so many varieties of circuits and equipment in use in 
mines, it is impractical to describe a specific inspection procedure 
that applies to all circuits and equipment in all instances.
    Consequently, a general type inspection procedure, such as that 
contained in this final rule, is necessary. The amount of detail needed 
for a given inspection is normally determined on a case-by-case basis, 
as the inspection takes place. For example, the testing of ground 
monitors would normally only require simple activation of readily 
available test switches; however, findings revealed during this portion 
of the inspection of the longwall circuits and equipment may indicate a 
need for more thorough examinations and tests. For example, if an ohm 
meter test determined that a condition existed in a cable, such as an 
inadvertent connection between a pilot wire and ground wire rendering a 
ground monitor inoperative, further examination and correction would be 
required to establish effective ground monitoring. For these reasons, 
the Agency concludes that the final rule require general type 
examinations and tests be conducted. Therefore, except for the change 
based on the Black Mesa decision, paragraph (a) of this section remains 
as proposed.
    Paragraph (b) of the final rule, like the proposed rule, requires 
that each ground-wire monitor and corresponding circuit be examined and 
tested at least once each 30 days to verify that it is operating 
properly and will cause the corresponding circuit-interrupting device 
to open. This procedure assures that ground-wire monitors and 
corresponding circuit-interrupting

[[Page 10994]]

devices will operate properly to deenergize the circuits that they 
monitor. A commenter suggested that the requirement for testing of 
ground-wire monitors be relocated to another section of the rule, or 
possibly Sec. 75.803--Fail safe ground check circuits on high-voltage 
resistance grounded systems. The Agency has determined that the 
important safety protection provided by these devices and their use on 
operating high-voltage longwall equipment necessitates placing ground 
monitor testing requirements in this section of the final rule. This is 
required in addition to other relevant testing requirements for other 
protective systems on high-voltage longwall equipment.
    Another commenter suggested that the testing be limited to the 
operation of appropriate control circuit test devices in the power 
center or high-voltage motor-starter enclosure, and indicated that it 
should not be necessary to open any explosion-proof enclosure or to 
disconnect any ground wire while testing a ground-wire monitor. These 
commenters suggested that language be added to the provision that 
specifies the test be initiated by operating the test switch provided 
as part of the ground-wire monitor, or a similar switch installed in 
the power center or the high-voltage motor-starter enclosure. As stated 
above, proper examination and testing of ground-wire monitors and 
associated circuits, which include pilot wires and grounding 
conductors, may require more than simple activation of a test switch 
that normally opens the pilot wire. Therefore, paragraph (b) of this 
section remains as proposed.
    Paragraph (c) of the final rule requires equipment to be 
immediately removed from service or immediately repaired when 
examinations or tests reveal a fire, electric shock, ignition, or 
operational hazard. This provision assures that equipment which may 
pose a danger to miners will not be used until the hazardous condition 
is corrected. Some commenters stated that the term ``immediately'' 
should be added to this provision. These commenters indicated that it 
is of utmost importance that whenever tests and examinations reveal 
malfunctions and defects, equipment must be repaired or removed from 
service immediately. They pointed out that operators may be reluctant 
to shut down a longwall operation to make necessary corrections and 
that confrontational situations and any misinterpretations could be 
avoided by adding this clarification to the standard.
    The Agency agrees with the commenter and has added the word 
``immediately'' to Sec. 75.821(c) of the final rule. ``Immediately'' is 
intended to reflect its plain meaning that the required action be 
without hesitation or delay. It is emphasized, however, that the rule 
is referring to those safety defects that are considered hazardous, as 
stated under Sec. 75.821(c). For example, some conditions, such as bare 
energized conductors in cables or conductors, present fire, electric 
shock, ignition, and possibly even operational hazards and require 
either immediate removal from service or immediate repair. However, 
conditions may exist that would not require immediate shutdown of 
equipment, but due to the nature of the condition, would permit 
continued operation of the equipment until material or parts necessary 
to correct the condition are procured, or would permit orderly shutdown 
of equipment prior to repair. For example, Sec. 75.816 of this final 
rule requires guarding of high-voltage cables in specific locations. 
Unless there are other extenuating circumstances such as damaged cable 
or bare conductors present, a torn portion of guarding material would 
not be judged a condition that would have to be corrected immediately. 
It is the Agency's intent that once a condition with the potential to 
result in a fire, electric shock, ignition, or operational hazard is 
revealed correction of the condition should begin immediately. This 
includes arranging for orderly shutdown or removal of the equipment for 
repair until the necessary repair parts are obtained and installed.
    Paragraph (d) of the final rule, like the proposed rule, requires 
the person who performs examinations and tests to certify by signature 
and date that they have been conducted. Also, a record is required for 
any unsafe condition found and any corrective action taken. This unsafe 
condition need not be an immediate hazard to be reported. In addition, 
certifications and records are required to be kept for at least one 
year and made available at the mine for inspection by authorized 
representatives of the Secretary and representatives of miners at the 
mine. Records and certifications of tests and repairs are valuable 
tools for mine operators and can be used to point out patterns of 
equipment defects and facilitate improvements in equipment maintenance 
and design. These records and certifications will assist in identifying 
that the required examinations were conducted, and will also assist in 
the investigation of accidents.
    A commenter suggested that requiring the examiner's signature is 
not necessary and eliminates other responsible persons from entering 
the information as is currently allowed. This commenter pointed out 
that the results of the examination could be allowed to be entered by 
the examiner or by a responsible mine official, or information could be 
transferred from a checklist filled out by the examiner. In response to 
this commenter, high-voltage longwalls contain complex circuits and 
equipment that require examinations and tests be conducted only by 
qualified persons knowledgeable about equipment function and operation. 
These persons routinely acquire this knowledge through numerous hours 
of education, training, and experience. Once inspections, including 
required examinations and tests, of high-voltage longwalls are 
conducted by qualified persons, it can be concluded that these 
individuals are the only ones that have the necessary detailed 
knowledge and understanding of the results of the inspection. Because 
of this, it is appropriate that only these persons certify by signature 
and date that the required examinations and tests have been conducted 
and that unsafe conditions found have been corrected and recorded. This 
approach is consistent with other examination and recordkeeping 
requirements promulgated by MSHA.
    Another commenter suggested that the operator maintain a written 
record of each test, examination, repair or adjustment of all circuit 
breakers protecting high-voltage circuits which enter any underground 
area of the coal mine and that such records be maintained in a book 
approved by the Secretary. These commenters indicated that such records 
are necessary to assure that tests and examinations have been made and 
would indicate which pieces of electrical equipment were tested and 
examined and which ones were not. They suggested that a reduction in 
the amount of recordkeeping diminishes the operator's accountability to 
provide proof that all equipment has been tested and examined. In 
response to this commenter, even though existing Sec. 75.512 requires 
examination of all electric equipment, proposed Secs. 75.814 through 
75.822 are specific to high-voltage longwall circuits and equipment and 
not just high-voltage circuit breakers. Since proper test, examination, 
and maintenance of circuits and equipment is considered to be of 
extreme importance for the protection of personnel, the Agency 
concluded it was necessary to draft an examination and testing standard 
for high-voltage longwall circuits and

[[Page 10995]]

equipment. As stated above, the wording of Sec. 75.821(d), which in 
part, requires that the person who completes the examination and tests 
certify by signature and date that they have been conducted. This 
approach is generally consistent with requirements in other regulations 
promulgated by the Agency. This certification and recording requirement 
only pertains to high-voltage longwall systems, including associated 
low- and medium-voltage circuits and equipment. The requirements of 
Sec. 75.512 remain in effect for circuits and equipment in the mine 
other than that used on high-voltage longwall systems. Therefore, 
paragraph (d) of this section remains as proposed.

Section 75.822  Underground High-Voltage Longwall Cables

    Section 75.822 of the final rule is new, derived in part from 
existing Sec. 75.804--Underground high-voltage cables. It has been 
added since the proposed rule in specific response to commenters, and 
is a logical outgrowth of this high-voltage longwall rulemaking. This 
section differs from the requirements of Sec. 75.804 by permitting the 
use of high-voltage cables that have an insulated center ground-check 
conductor that is smaller than a No. 10 AWG conductor. The Agency 
developed this new provision in response to industry requests and to 
accommodate new cable design technology that can either eliminate or 
significantly minimize inter-machine arcing due to the reduction of 
current induced into the ground-check conductor. This new cable design 
technology developed from MSHA and the industry's experience with using 
smaller ground-monitor conductor sizes in high-voltage longwall cables 
under MSHA granted modifications. This experience, together with 
comments from the high-voltage longwall rulemaking process, caused MSHA 
to conclude that such cable designs should be permitted under the final 
rule. The development of affordable smaller conductors resulted 
directly from the high-voltage longwall equipment design and use 
experience under granted modifications.
    Two commenters suggested that a regulation be developed to permit 
the use of high-voltage cables that have a center ground-check 
conductor smaller than a No. 10 AWG conductor that is presently 
required under Sec. 75.804(a). The commenters further stated that MSHA 
has allowed the use of a smaller ground-check conductor for high-
voltage cables through the use of Sec. 101(c) of the Mine Act for 
petitions for modification. One of these commenters stated that the use 
of a center ground-check conductor can either eliminate or 
significantly minimize inter-machine arcing and also provides improved 
ground-check monitor performance by reducing induced current into the 
ground-check conductor.
    The Agency agrees with these comments, and includes a new section 
permitting this cable design use in light of its experience with high-
voltage longwall petitions. As noted above, these new cable design 
provisions arise from technology developments referenced by commenters 
in response to the proposed rule and from the high-voltage longwall 
experience under the petition process. This section includes 
requirements from Sec. 75.804 and allows the use of high-voltage 
longwall equipment cables that are designed with a center ground-check 
insulated conductor smaller than No. 10 AWG and metallic shields around 
each power conductor. Acceptable cables are those manufactured to meet 
nationally recognized consensus standards, such as the Insulated Cable 
Engineers Association (ICEA) standards and, as provided by the final 
rule, are designed with a stranded ground-check conductor that is no 
smaller than No. 16 AWG and is located in the center interstice of the 
cable conductors. The national consensus standards are developed by 
recognized experts in their fields. These cables, through the Mine Act 
Sec. 101(c) petition for modification process, have been used on 
longwall mining equipment for the past several years and provide the 
necessary protection from physical damage or stress to the No. 16 AWG 
center ground-check conductor.
    For these reasons, the Agency has determined that allowing the use 
of a No. 16 AWG center ground-check conductor can provide equivalent or 
improved protection as provided by a regular No. 10 AWG conductor. 
Improved protection is provided by the No. 16 AWG ground-check 
conductor because it is located in the center of the cable creating 
cable conductor symmetry. This greatly minimizes induced currents and 
voltages that have been found to occur when using cables where the 
ground-check conductors are located in the interstices between the 
phase conductors. These induced currents and voltages can result in 
arcing, fire or ignition hazards. Using cables with No. 10 AWG 
conductors has required the installation of external arc-suppression 
devices to prevent induced currents and voltages. Therefore, permitting 
cables with No. 16 AWG conductors located in the center of the cables, 
brings a safer, more efficient, and less burdensome ground-wire monitor 
system to the mining industry. This small ground-check conductor size 
is not a requirement but is offered to give added flexibility to mine 
operators and to minimize their cost burden where feasible. This option 
became available to the coal industry and coal mine equipment 
manufacturers as it was developed and used in high-voltage longwall 
systems under the petition for modification process during the last 
seven years.
    With the advent of high-voltage longwall face equipment, the 
development and use of No. 16 AWG ground-check conductors for high-
voltage longwall equipment became an affordable technology with 
additional safety benefits. This standard also eliminates the need for 
Sec. 75.804(a) petitions for modification on longwalls for this purpose 
and facilitates the use of improved high-voltage cable designs. These 
cable designs should reduce the hazards associated with locating 
severed ground-check conductors, thereby discouraging the bypassing of 
ground-wire monitors when a cable has experienced a broken or severed 
ground-check conductor. Mines using this cable design have reported 
less downtime by having to locate and repair broken or severed ground-
check conductors.
    A commenter recommended that the word ``metallic'' not be used to 
describe the shielding that surrounds the individual power conductors 
and that the rule should allow the use of other materials to be 
incorporated in the construction of the shielding. The commenter did 
not specify what other types of materials should be used as shielding 
around the power conductors. Experience indicates that use of high-
voltage cables with metallic shielding that surrounds the individual 
power conductors provides the intended protection against electrical 
hazards. Thus, the Agency has retained the cable design specifications 
that incorporate metallic shielding around each power conductor.

Section 75.1002  Installation of Electric Equipment and Conductors; 
Permissibility

    This section of the final rule is derived from existing 
Secs. 75.1002--Location of trolley wires, trolley feeder wires, high-
voltage cables and transformers and 75.1002-1--Location of other 
electric equipment; requirements for permissibility and addresses 
requirements for conductors and cables used in or inby the last open 
crosscut, and electric equipment and conductors and cables used within 
150

[[Page 10996]]

feet of pillar workings. The final rule revises existing Sec. 75.1002 
and removes Sec. 75.1002-1, which prohibited the use of high-voltage 
cables inby the last open crosscut and within 150 feet of pillar 
workings or longwall faces. It also revises Sec. 75.1002 related to the 
use of permissible equipment in these areas.
    Paragraph (a) of the final rule, like the existing rule and 
proposed rule, continues to require that only permissible electric 
equipment be located within 150 feet of pillar workings or longwall 
faces. This equipment is specifically designed to protect miners 
against fire and explosion hazards in the mining face areas such as the 
longwall face where methane gas would likely accumulate and possibly 
cause an ignition or explosion.
    Paragraph (b) of the final rule, like the existing rule and 
proposed rule, limits the types of electric conductors and cables 
permitted in areas where permissible equipment is required. This 
section prohibits the installation of conductors such as trolley wires 
and trolley feeder wires in areas where permissible equipment is 
required. Such electric conductors could provide a ready ignition 
source and therefore must not be used where permissible equipment is 
required. Permissible equipment is defined under 30 CFR Sec. 18.2--
Definitions and under Sec. 318(i) of the Mine Act. Such equipment is 
specifically approved by MSHA for use in fire and explosive hazardous 
areas. However, the new final paragraph (b)(1), like the proposed rule, 
permits the use of shielded high-voltage longwall cable. Such shielding 
and design 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 permissible 
longwall equipment reduces 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 short-circuit and ground-fault 
protection against shock, fire, and explosion hazards. The final rule 
continues to prohibit the use of such nonpermissible equipment not 
specifically approved by MSHA for use near the actual coal extraction 
areas where increased fire and explosion hazards exist.
    The high-voltage longwall final rule does not apply to high-voltage 
continuous miner use within 150 feet of pillar workings. High-voltage 
continuous miner petitions granted under existing Sec. 75.1002 
(Sec. 75.1002(b) under this final rule) will remain in effect, and mine 
operators who do not have granted petitions in effect must file a 
petition for modification of Sec. 75.1002(b) for the future use of 
high-voltage continuous miners.
    In addition, the high-voltage longwall final rule does not apply to 
nonpermissible test and diagnostic equipment use. Previously granted 
petitions under existing Sec. 75.1002-1(a) (Sec. 75.1002(a) under this 
final rule) will remain in effect. After the effective date of this 
rule, mine operators who do not have granted petitions in effect must 
file a petition for modification for the use of nonpermissible test and 
diagnostic equipment under Sec. 75.1002(a).
    In response to a commenter's suggestion, MSHA has added the term 
``longwall faces'' to paragraph (b) of the section. While longwall 
faces are generally considered to be part of a pillar working, the use 
of this term more specifically identifies the place where conductors 
and cables can be used. The addition of this term also maintains 
consistency with paragraph (a). This term was used in proposed 
paragraph (a) to clarify that longwall faces are included as part of 
the pillar working.
    Paragraph (b)(1) of the final rule, like the proposed rule, permits 
the use of shielded high-voltage cables supplying power to permissible 
longwall equipment. Paragraphs (b)(2) through (b)(4) of the final rule, 
like the existing standards, permit the use of conductors and cables of 
intrinsically safe circuits, and cables and conductors supplying power 
to low- and medium-voltage permissible equipment in or inby the last 
open crosscut and within 150 feet of pillar workings or longwall faces.

Petitions for Modification

    On the effective date of this final rule, all existing petitions 
for modification for high-voltage longwall use under Sec. 75.1002 will 
be superseded. Operators are thereafter required to comply with the 
provisions of this final rule.

Derivation Table

    The following derivation table lists: (1) Each section number of 
the final rule and (2) The section number of the standard from which 
the section is derived (existing section).

                            Derivation Table
------------------------------------------------------------------------
                Final rule                        Existing section
------------------------------------------------------------------------
75.2......................................  Partly new.
75.813....................................  N/A.
75.814(a)(1)..............................  75.518-1 & 75.800.
75.814(a)(2)..............................  N/A.
75.814(a)(3)..............................  75.802.
75.814(a)(4)..............................  75.800.
75.814(a)(5) & (6)........................  N/A.
75.814(a)(7)..............................  75.800.
75.814(b), (c) & (d)......................  N/A.
75.814(e).................................  New (75.518-1).
75.815(a) & (b)...........................  75.808.
75.815(c).................................  75.520.
75.815(d)(1)..............................  75.601 & 75.808.
75.815(d)(2)..............................  75.705.
75.815(d)(3)..............................  75.511.
75.815(e).................................  75.520.
75.816 & 75.817...........................  75.807.
75.818(a).................................  75.705-6 and 75.812.
75.818(b).................................  75.705-7 & 75.705-8.
75.819....................................  N/A.
75.820....................................  75.153, 75.509, 75.511 &
                                             75.705.
75.821....................................  75.512, 75.512-1, 75.800-3 &
                                             75.800-4.
75.822....................................  N/A.
75.1002 (revised).........................  75.1002, 75.1002-1.
------------------------------------------------------------------------
N/A: Not Applicable.

Distribution Table

    The following distribution table lists: (1) Each section number of 
the existing standards and (2) The section number of the final rule 
which contains provisions derived from the corresponding existing 
section.

                           Distribution Table
------------------------------------------------------------------------
             Existing section                        Final rule
------------------------------------------------------------------------
75.2......................................  Partly new 75.2.
NA........................................  75.813.
75.518-1 & 75.808.........................  75.814(a)(1).
NA........................................  75.814(a)(2).
75.802....................................  75.814(a)(3).
75.800....................................  75.814(a)(4).
NA........................................  75.814(a)(5) & (6).
75.800....................................  75.814(7).
NA........................................  75.814(b), (c) & (d).
New (75.518-1)............................  75.814 (e).
75.808....................................  75.815 (a) & (b).
75.520....................................  75.815 (c).
75.601 & 75.808...........................  75.815 (d)(1).
75.705....................................  75.815 (d)(2).
75.511....................................  75.815 (d)(3).
75.520....................................  75.815 (e).
75.807....................................  75.816 & 75.817.
75.705-6 & 75.812.........................  75.818 (a).
75.705-7 & 75.705-8.......................  75.818 (b).
NA........................................  75.819.
75.153, 75.509, 75.511 75.705.............  75.820.
75.512, 75.512-1, 75.800-3 & 75.800-4.....  75.821.
NA........................................  75.822.
75.1002 (Revised) & 75.1002-1 (Removed)...  75.1002.
------------------------------------------------------------------------
NA--Not Applicable.

III. Paperwork Reduction Act

    The information collection requirements contained in this final 
rule

[[Page 10997]]

have been submitted to the Office of Management and Budget (OMB) for 
review under the Paperwork Reduction Act of 1995 (44 U.S.C. 3501-3520), 
as implemented by OMB in regulations at 5 CFR part 1320. The Paperwork 
Reduction Act of 1995 (PRA 95) defines collection of information as 
``the obtaining, causing to be obtained, soliciting, or requiring the 
disclosure to third parties or the public of facts or opinions by or 
for an agency regardless of form or format.''
    This rule contains information collection requirements for high-
voltage longwall operators in Sec. 18.53(h), Sec. 75.820(b), 
Sec. 75.820(e) and Sec. 75.821(d). Annual paperwork burden hours and 
costs from these provisions are given in the following table. The total 
first year paperwork burden hours and costs of the rule are 5,736 hours 
and $163,929, respectively. The total burden hours and costs in each 
year thereafter will be 5,732 hours and $163,806, respectively.
    Manufacturers seeking approval for longwall equipment continue to 
be required to submit applications for approval including related 
drawings, drawing lists, specifications, wiring diagrams, and 
descriptions. The paperwork burden for this application process is 
approved as part of a petition for modification, under OMB Control 
Number 1219-0065.
    The information collection requirements contained in this rule for 
part 75 were submitted to OMB for review under the Paperwork Reduction 
Act of 1995 and were approved under OMB Control Number 1219-0116. This 
Control Number, however, expired in 1994, and the information 
requirements have been resubmitted to OMB for reinstatement. In 
accordance with Sec. 1320.11(h) of the implementing regulations, OMB 
has 60 days from today's publication date in which to approve, 
disapprove, or instruct MSHA to make a change to the information 
collection requirements in this final rule.

                              Table of Annual Burden hours and Costs From the Rule
----------------------------------------------------------------------------------------------------------------
                                                                   Annual burden                   Annual burden
                                                   Annual burden     hours for     Annual burden     costs for
                                                     Hours in        each year       costs in        each year
                                                    first year      thereafter      first year      thereafter
----------------------------------------------------------------------------------------------------------------
Section 18.53(h)................................               7               3            $247            $124
Section 75.820(b) and (e).......................            1604            1604          45,831          45,831
Section 75.821(d)...............................            4125            4125         117,851         117,851
                                                 ---------------------------------------------------------------
    Total.......................................            5736            5732         163,929         163,806
----------------------------------------------------------------------------------------------------------------

IV. Executive Order 12866 and Regulatory Flexibility Act

    Executive Order 12866 requires that regulatory agencies assess both 
the costs and benefits of regulations. MSHA has determined that this 
final rule will not have an annual effect of $100 million or more on 
the economy and that, therefore, they are not an economically 
significant regulatory action pursuant to Sec. 3(f)(1) of Executive 
Order (E.O.) 12866. However, we have determined that this final rule is 
significant under Sec. 3(f)(4) of E.O. 12866, which defines a 
significant regulatory action as one that may ``* * * raise novel legal 
or policy issues arising out of legal mandates, the President's 
priorities, or the principles set forth in the Executive Order.'' MSHA 
completed a Regulatory Economic Analysis (REA) in which the economic 
impact of the rule is estimated. The REA is available from MSHA and is 
summarized as follows.

Population-at-Risk

    MSHA estimates that this rulemaking would initially affect 
approximately 14,229 miners at 43 underground coal mines and six mines 
employing about 1,667 miners that would begin using high-voltage 
longwall equipment in the first year of the rule. The rule would not 
increase costs to small mines, which MSHA has traditionally defined as 
having fewer than 20 employees, because such mines do not use longwall 
equipment.

Benefits

    The more stringent criteria and design features associated with 
high-voltage systems, such as compartment covers that are interlocked 
to prevent access to energized high-voltage conductors and equipment 
designed to facilitate safe testing procedures, decrease the likelihood 
of electrical accidents. In addition, high-voltage cables are required 
to be shielded around each conductor (SHD type) whereas medium-voltage 
cables can be shielded around the circumference of the cable (SHC 
type). The SHD cables are safer than the SHC cables because shielding 
the individual power conductors reduces the possibility of a short 
circuit that can cause a fire, or a shock and burn hazard when a miner 
touches a cable. The SHD shielding reduces the possibility of a shock 
hazard because an exposed energized conductor will contact the SHD 
shielding and activate the ground-fault protection, which removes power 
to the cable. The use of high-voltage SHD cables reduces the chances of 
cable damage which, in turn, reduces the chances of a miner coming into 
contact with an energized conductor(s).
    Further, the use of high voltage in longwall mining operations may 
reduce the number of power cables running between various pieces of 
longwall equipment. In certain situations, the cables may also be 
smaller, for example, 5,000-volt (high-voltage) power cables are 
smaller and weigh less than 1,000-volt (medium-voltage) power cables. 
As a result of fewer and lighter power cables, the risk of injuries 
from handling power cables during longwall installation, movement, or 
replacement may be reduced.
    Increased productivity gains can be realized when using high 
voltage rather than medium voltage. In cases where medium voltage is 
used to power larger motors and heavier duty longwall equipment, 
current (amperes) can increase, causing motors and/or cables to 
overheat. However, if high voltage rather than medium voltage is used 
to power the larger motors and heavier duty longwall equipment, current 
(amperes) is reduced, and the risk of overheating motors and/or cables 
diminishes. Also, motor start-up is easier when using high voltage. 
This increased reliability may reduce the amount of longwall equipment 
downtime, thereby enhancing coal productivity.
    Section 75.818(b)(1) and (2) requires that high-voltage insulated 
gloves, sleeves, and other insulated personal protective equipment be 
rated as Class 1 or higher, be visibly examined before each use for 
signs of damage, and that such protective equipment be removed

[[Page 10998]]

from the underground area of the mine when damaged or defective.
    Section 75.818(b)(3) requires that insulated personal protective 
equipment be electrically tested every six months.
    Section 75.820(d)(3) requires qualified electricians to wear 
properly rated rubber gloves in order to perform troubleshooting and 
testing on low- and medium-voltage circuits in a high-voltage 
compartment. Currently, petitions for modification do not have this 
requirement. Thus, Sec. 75.820(d)(3) provides additional safety 
protection during this troubleshooting and testing.
    Finally, the rule continues the same electrical safety requirements 
developed in the petitions for modification to use high-voltage 
longwalls.

Compliance Costs

    This rule will result in yearly net savings of $23,083,980. This 
includes a savings per conversion of $6,753,851 attributed to each 
medium-voltage longwall unit that converts to high-voltage usage. These 
conversion savings consist of $6,733,280 for accelerated production 
savings per unit, and $20,571 for filed petition savings per unit.
    The net economic effect of the rule includes substantially 
increased productivity and cost savings for each longwall unit that 
converts to high-voltage equipment and cables, and a small cost 
annually for each longwall unit that uses high-voltage equipment and 
cables. Accelerated production savings are savings due to the more 
productive high-voltage equipment being used sooner rather than later. 
Filed petition savings refer to savings due to eliminating legal fees 
and expenses connected with a filed petition. The elimination of the 
need to file petitions for modification to use high-voltage longwalls 
will reduce the costs associated with the petition process and will 
require less paperwork.
    MSHA estimates that the petition process would have imposed costs 
for legal fees and expenses of about $5,250 for an unopposed petition 
filing and $112,500 for an opposed petition requiring litigation, 
including proceedings before Administrative Law Judges, the Assistant 
Secretary, and courts of appeal. Since 14.3 percent (1 out of 7) of all 
petitions granted by MSHA in 1998 were contested and required an ALJ's 
decision, MSHA assumes this same percentage would be contested were 
future petitions to be filed. Thus, elimination of the petition process 
would generate a one-time filed petition savings per high-voltage 
longwall unit of $20,571.
    In addition, eliminating the petition process would produce further 
savings for medium-voltage longwall units that convert to high-voltage 
units. The rule would eliminate delayed production that could occur as 
a result of a mine not being able to synchronize initial start-up of 
its high-voltage longwall equipment with the granting of a petition. 
The medium-voltage longwall units that convert would have the 
opportunity to obtain higher productivity yields from the use of high 
voltage sooner under the rule than under current procedures. Based on 
an average 66.1 percent increased productivity of high-voltage 
longwalls over lower-voltage longwalls and an average delayed 
production time of 78 working days, MSHA estimates that the one-time 
conversion accelerated production savings due to the petition process 
would be about $6,733,280 per high-voltage longwall unit.
    With respect to individual provisions concerning the 43 existing 
mines that currently use high-voltage equipment and the medium-voltage 
longwall units that would shift to high voltage, Sec. 75.818(b)(4) 
would require mines to perform an electrical test of personal 
protective equipment every six months. Section 75.820(d)(3) would 
require electricians to wear properly-rated rubber gloves to perform 
troubleshooting and testing on low- and medium-voltage circuits that 
are contained in a compartment with high-voltage circuits. Compliance 
cost increases of $90 per longwall unit and $168 per longwall unit are 
identified with Secs. 75.818(b)(4) and 75.820(d)(3), respectively.

Economic Impact

    The rule enhances productivity in those affected mines because it 
allows more efficient high-voltage longwall equipment to be established 
more rapidly in the relatively few underground coal mines in which it 
can be profitably employed. MSHA has concluded that the rule will have 
only a small (but favorable) effect on coal output, price, and 
profitability.

Feasibility

    MSHA has concluded that the requirements of the final rule are both 
technologically and economically feasible.
    This final rule is not a technology-forcing standard and does not 
involve activities on the frontiers of scientific knowledge. The 
equipment testing, recordkeeping, and rubber glove requirements all 
involve standard procedures or simple, off-the-shelf technologies. 
Other provisions of the final rule will reduce recordkeeping and 
petition requirements.
    The final rule is clearly economically feasible insofar as it 
provides a yearly net savings of $23.08 million to high-voltage 
longwall mines. This includes a one-time savings of $6.75 million for 
each longwall mine that converts to high voltage as well as annual 
costs of $258 for each high-voltage longwall mine.

Regulatory Flexibility Act and Small Business Regulatory Enforcement 
Fairness Act (SBREFA)

    The Regulatory Flexibility Act (RFA) requires regulatory agencies 
to consider a rule's impact on small entities. For the purposes of the 
RFA and this certification, MSHA has analyzed the impact of the final 
rule and has determined that there will be a cost savings to small 
entities affected by this rule.
    MSHA will mail a copy of the final rule, including the preamble and 
regulatory flexibility certification statement, to all underground coal 
mine operators and miners' representatives. The final rule will also be 
placed on MSHA's Internet Homepage at http://www.msha.gov, under 
Statutory and Regulatory Information.
    In accordance with Sec. 605 of the RFA, MSHA certifies that this 
final rule will not have a significant adverse economic impact on a 
substantial number of small entities. No small governmental 
jurisdictions or nonprofit organizations are affected.
    Under the Small Business Regulatory Enforcement Fairness Act 
amendments to the RFA, MSHA must include in the final rule a factual 
basis for this certification. The Agency also must publish the 
regulatory flexibility certification in the Federal Register, along 
with its factual basis.

Factual Basis for Certification

    The Agency compared the gross costs of the rule for small mines in 
each sector to the revenue for that sector for both size categories 
analyzed (MSHA and Small Business Administration `small entity' 
definitions). Given that the gross compliance costs for small mines is 
substantially less than 1 percent of revenue and that net costs are 
negative, MSHA concludes that there is no significant cost impact of 
the rule on small entities that use high-voltage longwall units.
    Other small entities potentially affected by the rule are small 
manufacturers of high-voltage longwall equipment. MSHA concludes that 
the rule would not have a significant impact upon a substantial number 
of small

[[Page 10999]]

manufacturers of high-voltage longwall equipment.
    MSHA also has determined that there are no initial net compliance 
costs as a result of this rule. The final rule results in a net 
savings. Currently mine operators are required to file a petition for 
modification to use high-voltage longwall equipment. This is a costly 
and lengthy administrative process. This final rule increases safety, 
effectiveness, and efficiency in the use of high-voltage longwall 
equipment. The lengthy approval process will be eliminated. The Agency 
estimates that six existing longwall mines will convert to high voltage 
and an additional three new longwall mines each year will elect to 
adopt high-voltage technology in the future.

Unfunded Mandates Reform Act of 1995

    For purposes of the Unfunded Mandates Reform Act of 1995, as well 
as E.O. 12875, this rule does not include any Federal mandate that may 
result in increased expenditures by State, local, and tribal 
governments, or increased expenditures by the private sector of more 
than $100 million. MSHA is not aware of any State, local, or tribal 
government that either owns or operates underground coal mines.

Executive Order 13132

    MSHA has reviewed this rule in accordance with Executive Order 
13132 regarding federalism, and has determined that it does not have 
``federalism implications.'' The rule does 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.'' There are no 
underground coal mines or manufacturers of high-voltage longwall 
equipment owned or operated by any State governments.

Executive Order 13045

    In accordance with Executive Order 13045, MSHA has evaluated the 
environmental health and safety effect of the final rule on children. 
The Agency has determined that the final rule will have no effect on 
children.

Executive Order 13084

    In accordance with Executive Order 13084, MSHA certifies that the 
high-voltage longwall final rule does not impose substantial direct 
compliance costs on Indian tribal governments. MSHA is not aware of any 
Indian tribal governments which either own or operate underground coal 
mines or manufacturers high-voltage longwall equipment.

Executive Order 12630

    This rule is not subject to Executive Order 12630, Governmental 
Actions and Interference with Constitutionally Protected Property 
Rights, because it does not involve implementation of a policy with 
takings implications.

Executive Order 12988

    This regulation has been drafted and reviewed in accordance with 
Executive Order 12988, Civil Justice Reform, and will not unduly burden 
the Federal court system. The regulation has been written so as to 
minimize litigation and provide a clear legal standard for affected 
conduct, and has been reviewed carefully to eliminate drafting errors 
and ambiguities.

Executive Order 13211 (Energy)

    In accordance with Executive Order 13211, MSHA has reviewed this 
final rule for its energy impacts. We have determined that the 
Executive Order does not apply to this final rule for the following 
reasons. One, this rulemaking is not considered a ``significant 
regulatory action'' under Executive Order 12866 and therefore the 
action does not meet the criteria listed in Executive Order 13211 
requiring a Statement of Energy Effects. Two, the proposed rule was 
published before the effective date of the Executive Order. Three, MSHA 
has determined that this final rule will not have any adverse effects 
on energy supply, distribution, or use. To the contrary, as summarized 
in the economic analysis, MSHA expects accelerated coal production 
because of the implementation of this final rule. Therefore, no 
reasonable alternatives to this action are necessary.

List of Subjects

30 CFR Part 18

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

30 CFR Part 75

    High-voltage longwall, Incorporation by reference, Mandatory safety 
standards, Mine safety and health, Underground coal mines.

    Dated: February 25, 2002.
Dave D. Lauriski,
Assistant Secretary of Labor for Mine Safety and Health.

    For the reasons set out in the preamble, chapter I of title 30 of 
the Code of Federal Regulations is amended 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, 961.


    2. Add Sec. 18.53 to subpart B of part 18 to read as follows:


Sec. 18.53  High-voltage longwall mining systems.

    (a) In each high-voltage motor-starter enclosure, with the 
exception of a controller on a high-voltage shearer, the disconnect 
device compartment, control/communications compartment, and motor 
contactor compartment must be separated by barriers or partitions to 
prevent exposure of personnel to energized high-voltage conductors or 
parts. In each motor-starter enclosure on a high-voltage shearer, the 
high-voltage components must be separated from lower voltage components 
by barriers or partitions to prevent exposure of personnel to energized 
high-voltage conductors or parts. Barriers or partitions must be 
constructed of grounded metal or nonconductive insulating board.
    (b) Each cover of a compartment in the high-voltage motor-starter 
enclosure containing high-voltage components must be equipped with at 
least two interlock switches arranged to automatically deenergize the 
high-voltage components within that compartment when the cover is 
removed.
    (c) Circuit-interrupting devices must be designed and installed to 
prevent automatic reclosure.
    (d) Transformers with high-voltage primary windings that supply 
control voltages must incorporate grounded electrostatic (Faraday) 
shielding between the primary and secondary windings. The shielding 
must be connected to equipment ground by a minimum No. 12 AWG grounding 
conductor. The secondary nominal voltage must not exceed 120 volts, 
line to line.
    (e) Test circuits must be provided for checking the condition of 
ground-wire monitors and ground-fault protection without exposing 
personnel to energized circuits. Each ground-test circuit must inject a 
primary current of 50 percent or less of the current rating of the 
grounding resistor through the current transformer and cause each 
corresponding circuit-interrupting device to open.
    (f) Each motor-starter enclosure, with the exception of a 
controller on a high-voltage shearer, must be equipped with

[[Page 11000]]

a disconnect device installed to deenergize all high-voltage power 
conductors extending from the enclosure when the device is in the 
``open'' position.
    (1) When multiple disconnect devices located in the same enclosure 
are used to satisfy the above requirement they must be mechanically 
connected to provide simultaneous operation by one handle.
    (2) The disconnect device must be rated for the maximum phase-to-
phase voltage and the full-load current of the circuit in which it is 
located, and installed so that--
    (i) Visual observation determines that the contacts are open 
without removing any cover;
    (ii) The load-side power conductors are grounded when the device is 
in the ``open'' position;
    (iii) The device can be locked in the ``open'' position;
    (iv) When located in an explosion-proof enclosure, the device must 
be designed and installed to cause the current to be interrupted 
automatically prior to the opening of the contacts; and
    (v) When located in a non-explosion-proof enclosure, the device 
must be designed and installed to cause the current to be interrupted 
automatically prior to the opening of the contacts, or the device must 
be capable of interrupting the full-load current of the circuit.
    (g) Control circuits for the high-voltage motor starters must be 
interlocked with the disconnect device so that--
    (1) The control circuit can be operated with an auxiliary switch in 
the ``test'' position only when the disconnect device is in the open 
and grounded position; and
    (2) The control circuit can be operated with the auxiliary switch 
in the ``normal'' position only when the disconnect switch is in the 
closed position.
    (h) A study to determine the minimum available fault current must 
be submitted to MSHA to ensure adequate protection for the length and 
conductor size of the longwall motor, shearer and trailing cables.
    (i) Longwall motor and shearer cables with nominal voltages greater 
than 660 volts must be made of a shielded construction with a grounded 
metallic shield around each power conductor.
    (j) High-voltage motor and shearer circuits must be provided with 
instantaneous ground-fault protection of not more than 0.125-amperes. 
Current transformers used for this protection must be of the single-
window type and must be installed to encircle all three phase 
conductors.
    (k) Safeguards against corona must be provided on all 4,160 voltage 
circuits in explosion-proof enclosures.
    (l) The maximum pressure rise within an explosion-proof enclosure 
containing high-voltage switchgear must be limited to 0.83 times the 
design pressure.
    (m) High-voltage electrical components located in high-voltage 
explosion-proof enclosures must not be coplanar with a single plane 
flame-arresting path.
    (n) 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:

                                                               Minimum Creepage Distances
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                          Minimum creepage distances (inches) for comparative tracking index (CTI) range
                                                                                                                \1\
           Phase to phase voltage                 Points of  measure     -------------------------------------------------------------------------------
                                                                          CTI500  380CTI500  175CTI380       CTI175
--------------------------------------------------------------------------------------------------------------------------------------------------------
2,400......................................  -                            1.50                 1.95                  2.40               2.90
                                             -G                                 1.00                 1.25                  1.55               1.85
4,160......................................  -                            2.40                 3.15                  3.90               4.65
                                             -G                                 1.50                 1.95                  2.40              2.90
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Assumes that all insulation is rated for the applied voltage or higher.

    (o) Explosion-proof 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            B            C
----------------------------------------------------------------------------------------------------------------
\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.
\1\ Column A specifies the MFD for enclosures that have available 3-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 3-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 3-phase bolted short-circuit
  currents greater than 15,000 and less than or equal to 20,000 amperes rms.
\4\ Not Applicable--MSHA doesn't allow aluminum wall or covers to be \1/4\ inch or less in thickness (Section
  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.

[[Page 11001]]

    (i) Steel Wall/Cover:
    [GRAPHIC] [TIFF OMITTED] TR11MR02.001
    
    (ii) Aluminum Wall/Cover:
    [GRAPHIC] [TIFF OMITTED] TR11MR02.002
    
Where C is 1.4 for 2,400 volt systems or 3.0 for 4,160 volt systems, 
Isc is the 3-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.
    (p) The following static pressure test must be performed on each 
prototype design of explosion-proof enclosures containing high-voltage 
switchgear prior to the explosion tests. The static pressure test must 
also be performed on every explosion-proof enclosure containing high-
voltage switchgear, at the time of manufacture, unless the manufacturer 
uses an MSHA accepted quality assurance procedure covering inspection 
of the enclosure. Procedures must include a detailed check of parts 
against the drawings to determine that the parts and the drawings 
coincide and that the minimum requirements stated in part 18 have been 
followed with respect to materials, dimensions, configuration and 
workmanship.
    (1) Test procedure. (i) The enclosure must be internally 
pressurized to at least the design pressure, maintaining the pressure 
for a minimum of 10 seconds.
    (ii) Following the pressure hold, the pressure must be removed and 
the pressurizing agent removed from the enclosure.
    (2) Acceptable performance. (i) The enclosure during pressurization 
must not exhibit--
    (A) Leakage through welds or casting; or
    (B) Rupture of any part that affects the explosion-proof integrity 
of the enclosure.
    (ii) The enclosure following removal of the pressurizing agents 
must not exhibit--
    (A) Visible cracks in welds;
    (B) Permanent deformation exceeding 0.040 inches per linear foot; 
or
    (C) Excessive clearances along flame-arresting paths following 
retightening of fastenings, as necessary.

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. Amend Sec. 75.2 by adding the following definitions:


Sec. 75.2  Definitions.

* * * * *
    Adequate interrupting capacity. The ability of an electrical 
protective device, based upon its required and intended application, to 
safely interrupt values of current in excess of its trip setting or 
melting point.
* * * * *
    Approval documentation. Formal papers issued by the Mine Safety and 
Health Administration which describe and illustrate the complete 
assembly of electrical machinery or accessories which have met the 
applicable requirements of 30 CFR part 18.
* * * * *
    Circuit-interrupting device. A device designed to open and close a 
circuit by nonautomatic means and to open the circuit automatically at 
a predetermined overcurrent value without damage to the device when 
operated within its rating.
* * * * *
    Ground fault or grounded phase. An unintentional connection between 
an electric circuit and the grounding system.
    Motor-starter enclosure. An enclosure containing motor starting 
circuits and equipment.
    Nominal voltage. The phase-to-phase or line-to-line root-mean-
square value assigned to a circuit or system for designation of its 
voltage class, such as 480 or 4,160 volts. Actual voltage at which the 
circuit or system operates may vary from the nominal voltage within a 
range that permits satisfactory operation of equipment.
* * * * *
    Short circuit. An abnormal connection of relatively low impedance, 
whether made accidentally or intentionally, between two points of 
different potential.
* * * * *

    5. Part 75, Subpart I, Underground High-Voltage Distribution, is 
amended by adding Secs. 75.813 through 75.822 and Appendix A under a 
new undesignated center heading, high-voltage longwalls, to read as 
follows:
Sec.

High-Voltage Longwalls

75.813   High-voltage longwalls; scope.
75.814   Electrical protection.
75.815   Disconnect devices.
75.816   Guarding of cables.
75.817   Cable handling and support systems.
75.818   Use of insulated cable handling equipment.
75.819   Motor-starter enclosures; barriers and interlocks.
75.820   Electrical work; troubleshooting and testing.
75.821   Testing, examination and maintenance.
75.822   Underground high-voltage longwall cables.
Appendix A to Subpart I--Diagrams of Inby and Outby Switching
* * * * *

High-Voltage Longwalls


Sec. 75.813  High-voltage longwalls; scope.

    Sections 75.814 through 75.822 of this part are electrical safety 
standards that apply to high-voltage longwall circuits and equipment. 
All other existing standards in 30 CFR must also apply to these 
longwall circuits and equipment where appropriate.


Sec. 75.814  Electrical protection.

    (a) High-voltage circuits must be protected against short circuits, 
overloads, ground faults, and undervoltages by circuit-interrupting 
devices of adequate interrupting capacity as follows:
    (1) Current settings of short-circuit protective devices must not 
exceed the setting specified in approval documentation, or seventy-five 
percent of the minimum available phase-to-phase short-circuit current, 
whichever is less.

[[Page 11002]]

    (2) Time-delay settings of short-circuit protective devices used to 
protect any cable extending from the section power center to a motor-
starter enclosure must not exceed the settings specified in approval 
documentation, or 0.25-second, whichever is less. Time delay settings 
of short-circuit protective devices used to protect motor and shearer 
circuits must not exceed the settings specified in approval 
documentation, or 3 cycles, whichever is less.
    (3) Ground-fault currents must be limited by a neutral grounding 
resistor to not more than--
    (i) 6.5 amperes when the nominal voltage of the power circuit is 
2,400 volts or less; or
    (ii) 3.75 amperes when the nominal voltage of the power circuit 
exceeds 2,400 volts.
    (4) High-voltage circuits extending from the section power center 
must be provided with--
    (i) Ground-fault protection set to cause deenergization at not more 
than 40 percent of the current rating of the neutral grounding 
resistor;
    (ii) A backup ground-fault detection device to cause deenergization 
when a ground fault occurs with the neutral grounding resistor open; 
and
    (iii) Thermal protection for the grounding resistor that will 
deenergize the longwall power center if the resistor is subjected to a 
sustained ground fault. The thermal protection must operate at either 
50 percent of the maximum temperature rise of the grounding resistor, 
or 150 deg. C (302 deg. F), whichever is less, and must open the 
ground-wire monitor circuit for the high-voltage circuit supplying the 
section power center. The thermal protection must not be dependent upon 
control power and may consist of a current transformer and overcurrent 
relay.
    (5) High-voltage motor and shearer circuits must be provided with 
instantaneous ground-fault protection set at not more than 0.125-
ampere.
    (6) Time-delay settings of ground-fault protective devices used to 
provide coordination with the instantaneous ground-fault protection of 
motor and shearer circuits must not exceed 0.25-second.
    (7) Undervoltage protection must be provided by a device which 
operates on loss of voltage to cause and maintain the interruption of 
power to a circuit to prevent automatic restarting of the equipment.
    (b) Current transformers used for the ground-fault protection 
specified in paragraphs (a)(4)(i) and (5) of this section must be 
single window-type and must be installed to encircle all three phase 
conductors. Equipment safety grounding conductors must not pass through 
or be connected in series with ground-fault current transformers.
    (c) Each ground-fault current device specified in paragraphs 
(a)(4)(i) and (5) of this section must be provided with a test circuit 
that will inject a primary current of 50 percent or less of the current 
rating of the grounding resistor through the current transformer and 
cause each corresponding circuit-interrupting device to open.
    (d) Circuit-interrupting devices must not reclose automatically.
    (e) Where two or more high-voltage cables are used to supply power 
to a common bus in a high-voltage enclosure, each cable must be 
provided with ground-wire monitoring. The ground-wire monitoring 
circuits must cause deenergization of each cable when either the 
ground-monitor or grounding conductor(s) of any cable become severed or 
open. On or after May 10, 2002, parallel connected cables on newly 
installed longwalls must be protected as follows:
    (1) When one circuit-interrupting device is used to protect 
parallel connected cables, the circuit-interrupting device must be 
electrically interlocked with the cables so that the device will open 
when any cable is disconnected; or
    (2) When two or more parallel circuit-interrupting devices are used 
to protect parallel connected cables, the circuit-interrupting devices 
must be mechanically and electrically interlocked. Mechanical 
interlocking must cause all devices to open simultaneously and 
electrical interlocking must cause all devices to open when any cable 
is disconnected.


Sec. 75.815  Disconnect devices.

    (a) The section power center must be equipped with a main 
disconnecting device installed to deenergize all cables extending to 
longwall equipment when the device is in the ``open'' position. See 
Figures I-1 and I-2 in Appendix A to this subpart I.
    (b) Disconnecting devices for motor-starter enclosures must be 
maintained in accordance with the approval requirements of paragraph 
(f) of Sec. 18.53 of part 18 of this chapter. The compartment for the 
disconnect device must be provided with a caution label to warn miners 
against entering the compartment before deenergizing the incoming high-
voltage circuits to the compartment.
    (c) Disconnecting devices must be rated for the maximum phase-to-
phase voltage of the circuit in which they are installed, and for the 
full-load current of the circuit that is supplied power through the 
device.
    (d) Each disconnecting device must be designed and installed so 
that --
    (1) Visual observation determines that the contacts are open 
without removing any cover;
    (2) All load power conductors can be grounded when the device is in 
the ``open'' position; and
    (3) The device can be locked in the ``open'' position.
    (e) Disconnecting devices, except those installed in explosion-
proof enclosures, must be capable of interrupting the full-load current 
of the circuit or designed and installed to cause the current to be 
interrupted automatically prior to the opening of the contacts of the 
device. Disconnecting devices installed in explosion-proof enclosures 
must be maintained in accordance with the approval requirements of 
paragraph (f)(2)(iv) of Sec. 18.53 of part 18 of this chapter.


Sec. 75.816  Guarding of cables.

    (a) High-voltage cables must be guarded at the following locations:
    (1) Where persons regularly work or travel over or under the 
cables.
    (2) Where the cables leave cable handling or support systems to 
extend to electric components.
    (b) Guarding must minimize the possibility of miners contacting the 
cables and protect the cables from damage. The guarding must be made of 
grounded metal or nonconductive flame-resistant material.


Sec. 75.817  Cable handling and support systems.

    Longwall mining equipment must be provided with cable-handling and 
support systems that are constructed, installed and maintained to 
minimize the possibility of miners contacting the cables and to protect 
the high-voltage cables from damage.


Sec. 75.818  Use of insulated cable handling equipment.

    (a) Energized high-voltage cables must not be handled except when 
motor or shearer cables need to be trained. When cables need to be 
trained, high-voltage insulated gloves, mitts, hooks, tongs, slings, 
aprons, or other personal protective equipment capable of providing 
protection against shock hazard must be used to prevent direct contact 
with the cable.
    (b) High-voltage insulated gloves, sleeves, and other insulated 
personal protective equipment must--
    (1) Have a voltage rating of at least Class 1 (7,500 volts) that 
meets or

[[Page 11003]]

exceeds ASTM F496-97, ``Standard Specification for In-Service Care of 
Insulating Gloves and Sleeves'' (1997).
    (2) Be examined before each use for visible signs of damage;
    (3) Be removed from the underground area of the mine or destroyed 
when damaged or defective; and
    (4) Be electrically tested every 6 months in accordance with 
publication ASTM F496-97. ASTM F496-97 (Standard Specification for In-
Service Care of Insulating Gloves and Sleeves, 1997) is incorporated by 
reference and may be inspected at any Coal Mine Health and Safety 
District and Subdistrict Office, or at MSHA's Office of Standards, 4015 
Wilson Boulevard, Arlington, VA., and at the Office of the Federal 
Register, 800 North Capitol Street, NW., Suite 700, Washington, DC. In 
addition, copies of the document can be purchased from the American 
Society for Testing and Materials, 100 Barr Harbor Drive, West 
Conshohocken, Pennsylvania 19428-2959. This incorporation by reference 
was approved by the Director of the Federal Register in accordance with 
5 U.S.C. 552(a) and 1 CFR part 51.


Sec. 75.819  Motor-starter enclosures; barriers and interlocks.

    Compartment separation and cover interlock switches for motor-
starter enclosures must be maintained in accordance with the approval 
requirements of paragraphs (a) and (b) of Sec. 18.53 of part 18 of this 
chapter.


Sec. 75.820  Electrical work; troubleshooting and testing.

    (a) Electrical work on all circuits and equipment associated with 
high-voltage longwalls must be performed only by persons qualified 
under Sec. 75.153 to perform electrical work on all circuits and 
equipment.
    (b) Prior to performing electrical work, except for troubleshooting 
and testing of energized circuits and equipment as provided for in 
paragraph (d) of this section, a qualified person must do the 
following:
    (1) Deenergize the circuit or equipment with a circuit-interrupting 
device.
    (2) Open the circuit disconnecting device. On high-voltage 
circuits, ground the power conductors until work on the circuit is 
completed.
    (3) Lock out the disconnecting device with a padlock. When more 
than one qualified person is performing work, each person must install 
an individual padlock.
    (4) Tag the disconnecting device to identify each person working 
and the circuit or equipment on which work is being performed.
    (c) Each padlock and tag must be removed only by the person who 
installed them, except that, if that person is unavailable at the mine, 
the lock and tag may be removed by a person authorized by the operator, 
provided--
    (1) The authorized person is qualified under paragraph (a) of this 
section; and
    (2) The operator ensures that the person who installed the lock and 
tag is aware of the removal before that person resumes work on the 
affected circuit or equipment.
    (d) Troubleshooting and testing of 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
    (3) By persons qualified to perform electrical work and who wear 
protective gloves on circuits that exceed 40 volts in accordance with 
the following table:

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

    (4) Rubber insulating gloves must be rated at least for the nominal 
voltage of the circuit when the voltage of the circuit exceeds 120 
volts nominal and is not intrinsically safe.
    (e) Before troubleshooting and testing a low- or medium-voltage 
circuit contained in a compartment with a high-voltage circuit, the 
high-voltage circuit must be deenergized, disconnected, grounded, 
locked out and tagged in accordance with paragraph (b) of this section.
    (f) Prior to the installation or removal of conveyor belt 
structure, high-voltage cables extending from the section power center 
to longwall equipment and located in the belt entries must be:
    (1) Deenergized; or
    (2) Guarded in accordance with Sec. 75.816 of this part, at the 
location where the belt structure is being installed or removed; or
    (3) Located at least 6.5 feet above the mine floor.


Sec. 75.821  Testing, examination and maintenance.

    (a) At least once every 7 days, a person qualified in accordance 
with Sec. 75.153 to perform electrical work on all circuits and 
equipment must test and examine each unit of high-voltage longwall 
equipment and circuits to determine that electrical protection, 
equipment grounding, permissibility, cable insulation, and control 
devices are being properly maintained to prevent fire, electrical 
shock, ignition, or operational hazards from existing on the equipment. 
Tests must include activating the ground-fault test circuit as required 
by Sec. 75.814(c).
    (b) Each ground-wire monitor and associated circuits must be 
examined and tested at least once each 30 days to verify proper 
operation and that it will cause the corresponding circuit-interrupting 
device to open.
    (c) When examinations or tests of equipment reveal a fire, 
electrical shock, ignition, or operational hazard, the equipment must 
be removed from service immediately or repaired immediately.
    (d) At the completion of examinations and tests required by this 
section, the person who makes the examinations and tests must certify 
by signature and date that they have been conducted. A record must be 
made of any unsafe condition found and any corrective action taken. 
Certifications and records must be kept for at least one year and must 
be made available for inspection by authorized representatives of the 
Secretary and representatives of miners.


Sec. 75.822  Underground high-voltage longwall cables.

    In addition to the high-voltage cable design specifications in 
Sec. 75.804 of this part, high-voltage cables for use on longwalls may 
be a type SHD cable with a center ground-check conductor no smaller 
than a No. 16 AWG stranded conductor. The cables must be MSHA accepted 
as flame-resistant under part 18 or approved under subpart K of part 7.

[[Page 11004]]

Sec. 75.1002-1  [Removed]

    6. Remove Sec. 75.1002-1.

    7. Revise Sec. 75.1002 to read as follows:


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

    (a) Electric equipment must be permissible and maintained in a 
permissible condition when such equipment is located within 150 feet of 
pillar workings or longwall faces.
    (b) Electric conductors and cables installed in or inby the last 
open crosscut or within 150 feet of pillar workings or longwall faces 
must be--
    (1) Shielded high-voltage cables supplying power to permissible 
longwall equipment;
    (2) Interconnecting conductors and cables of permissible longwall 
equipment;
    (3) Conductors and cables of intrinsically safe circuits; and
    (4) Cables and conductors supplying power to low- and medium-
voltage permissible equipment.
BILLING CODE 4510-43-P

[[Page 11005]]

[GRAPHIC] [TIFF OMITTED] TR11MR02.000

[FR Doc. 02-4863 Filed 3-8-02; 8:45 am]
BILLING CODE 4510-43-C