[Federal Register Volume 75, Number 65 (Tuesday, April 6, 2010)]
[Rules and Regulations]
[Pages 17529-17553]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-7309]


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DEPARTMENT OF LABOR

Mine Safety and Health Administration

30 CFR Parts 18 and 75

RIN 1219-AB34


High-Voltage Continuous Mining Machine Standard for Underground 
Coal Mines

AGENCY: Mine Safety and Health Administration, Labor.

ACTION: Final rule.

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SUMMARY: This final rule revises the Mine Safety and Health 
Administration's (MSHA's) electrical safety standards for the 
installation, use, and maintenance of high-voltage continuous mining 
machines in underground coal mines. It also revises MSHA's design 
requirements for approval of these mining machines. The final rule will 
allow mine operators to use high-voltage continuous mining machines 
with enhanced safety protection against fires, explosions, and shock 
hazards and will facilitate the use of advanced equipment designs.

DATES: The final rule is effective on June 7, 2010. The incorporation 
by reference in this rule is approved by the Director of the Federal 
Register as of June 7, 2010.

FOR FURTHER INFORMATION CONTACT: Patricia W. Silvey, Director, Office 
of Standards, Regulations, and Variances, MSHA, 1100 Wilson Boulevard, 
Room 2350, Arlington, Virginia 22209-3939. Ms. Silvey can be reached at 
[email protected] (e-mail), 202-693-9440 (voice), or 202-693-9441 
(facsimile). (These are not toll-free numbers.)

SUPPLEMENTARY INFORMATION: The outline of this final rule is as 
follows:

I. Introduction
    A. Background
    B. Petition for Modification (PFM) Requirements in the Final 
Rule
II. Discussion of the Final Rule
    A. General Discussion--Part 18--Electric Motor-Driven Mine 
Equipment and Accessories
    B. General Discussion--Part 75--Mandatory Safety Standards--
Underground Coal Mines
III. Section-by-Section Analysis
    A. Part 18--Electric Motor-Driven Mine Equipment and Accessories
    B. Part 75--Mandatory Safety Standards--Underground Coal Mines
IV. Executive Order 12866: Regulatory Planning and Review
    A. Population at Risk
    B. Benefits
    C. Compliance Costs
V. Feasibility
    A. Technological Feasibility
    B. Economic Feasibility
VI. Regulatory Flexibility Act (RFA) and Small Business Regulatory 
Enforcement Fairness Act (SBREFA)
    A. Definition of a Small Mine
    B. Factual Basis for Certification
VII. Paperwork Reduction Act of 1995
    A. Elimination of Burden Hours
    B. Annual Burden Hours
    C. Details
VIII. Other Regulatory Considerations
    A. The Unfunded Mandates Reform Act of 1995
    B. Executive Order 13132: Federalism
    C. The Treasury and General Government Appropriations Act of 
1999: Assessment of Federal Regulations and Policies on Families
    D. Executive Order 12630: Government Actions and Interference 
With Constitutionally Protected Property Rights
    E. Executive Order 12988: Civil Justice Reform
    F. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    G. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

[[Page 17530]]

I. Introduction

A. Background

    Horsepower for electrical equipment in mines has increased over the 
years. The voltages required to operate this equipment have also 
increased to accommodate the design of safe, practical, and efficient 
equipment. Because of the industry's need for higher voltages and the 
marked improvement in the design and manufacturing technology of high-
voltage components, MSHA has established requirements for use of high-
voltage electrical equipment such as longwall systems. This rule 
establishes additional requirements to address the use and approval of 
high-voltage continuous mining machines. These additional requirements 
preserve safety and health protections for miners.
    MSHA's existing standards do not allow the use of high-voltage 
continuous mining machines because high-voltage mining machines were 
not available when the standards were developed. MSHA has granted 52 
Petitions for Modification (PFMs) since 1997 to allow mine operators to 
use this equipment. In granting the PFMs, MSHA determined that the 
methods the mine operator proposed to follow when using the high-
voltage equipment would at all times guarantee no less than the same 
measure of protection afforded the miners by the existing standards.
    On July 16, 2004, MSHA published a proposal (69 FR 42812) to 
establish design requirements in part 18 for approval of high-voltage 
continuous mining machines operating in production areas of underground 
mines. The proposal also included new requirements in part 75 for the 
installation, use, and maintenance of high-voltage continuous mining 
machines in underground coal mines.
    In the proposal, MSHA announced that it would hold four public 
hearings in September 2004, and would allow comments through October 
14, 2004. However, on August 23, 2004, MSHA published a notice changing 
the public hearing dates to November 2004 and extending the comment 
period to December 10, 2004 (69 FR 51787). Based on the review of all 
comments and testimony, MSHA re-proposed provisions related to the 
types of trailing cables that could be used with high-voltage 
continuous mining machines and the types of cable handling equipment 
that must be used when handling energized high-voltage trailing cables 
(71 FR 15359, March 28, 2006). In developing the final rule, MSHA 
considered the comments, hearing testimony, and granted PFMs.

B. Petition for Modification Requirements in the Final Rule

    The final rule includes most of the requirements that were in the 
granted PFMs. In each instance where a PFM requirement was not included 
in the rule, MSHA has addressed the Agency's rationale in the section-
by-section analysis of the preamble.
    This final rule supersedes all PFMs granted prior to the effective 
date, and eliminates the need for mine operators to file for a PFM to 
use high-voltage continuous mining machines with voltage up to 2,400 
volts.

II. Discussion of the Final Rule

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

    The final rule addresses design requirements for approval of high-
voltage continuous mining machines. The rule is intended to prevent the 
following hazards:
    (1) High-voltage arcing;
    (2) Ignition of a methane-air mixture surrounding the machine if an 
arc or methane explosion occurs within the explosion-proof enclosure;
    (3) Enclosure failure from an increased pressure rise if an arc or 
methane explosion occurs within the explosion-proof enclosure; and
    (4) Electrical shock hazards to miners when working with or around 
high-voltage equipment.
    One commenter stated that the proposal did not provide the same 
level of safety that some of the granted PFMs provided. This commenter 
expressed concern that MSHA was trying to issue a one-size-fits-all 
regulation while mine-specific PFMs better assure safety. MSHA does not 
believe that the final rule represents a generic approach or 
compromises safety. MSHA reviewed all provisions contained in granted 
PFMs and the final rule includes most of the provisions. However, in 
some cases, the Agency revised the language in the PFMs to allow more 
flexibility for mine specific conditions. The Agency explained at the 
public hearing that Part 18 covers this commenter's examples and should 
eliminate the concerns. Additionally, the final rule incorporates 
additional safety measures such as short-circuit, under-voltage, 
sensitive ground-fault protection, a look-ahead circuit, cable handling 
methods, and cable inspection procedures that would assure the same 
level of safety as the granted PFMs.
    This final rule provides a mining environment as safe as the 
existing environment and facilitates the use of advanced equipment 
designs.

B. General Discussion--Part 75--Mandatory Safety Standards--Underground 
Coal Mines

    This final rule revises 30 CFR Part 75 to establish mandatory 
electrical safety standards for the proper installation of high-voltage 
continuous mining machines, electrical and mechanical protection of the 
equipment, handling of trailing cables, and procedures for performing 
electrical work. These safety standards include new provisions as well 
as most of the provisions contained in granted PFMs.
    There are 27 high-voltage continuous mining machines used in 8 
underground coal mines that have been granted PFMs. Some of the 
requirements in this final rule are not included in those PFMs. 
Accordingly, mine operators with granted PFMs who wish to continue 
using high-voltage continuous mining machines will be required to 
comply with the additional requirements specified in this final rule. 
These additional requirements include new testing and recordkeeping 
requirements for tramming the machine in and out of the mine. In 
addition, there may be other new provisions that mine operators must 
adopt, such as following the cable manufacturers' recommended 
procedures when pulling the trailing cable with equipment other than 
the continuous mining machine (See Sec.  75.828).
    The final rule also revises Sec.  75.1002 by adding paragraph 
(b)(5) to allow the use of high-voltage continuous mining machines in 
areas where permissible equipment is required.

III. Section-by-Section Analysis

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

Section 18.54 High-Voltage Continuous Mining Machines
    Final Sec.  18.54(a) is derived from existing requirements for 
high-voltage longwall mining systems and is similar to the proposal. 
The final rule retains the proposed requirement that low- and medium-
voltage circuits in each motor-starter enclosure be separated from 
high-voltage circuits by barriers, partitions, or covers. The purpose 
of this provision is to protect persons from coming in contact with 
energized high-voltage conductors or parts when testing and 
troubleshooting low- and medium-voltage circuits.
    Several commenters expressed concern over this proposal. They 
indicated that in order to comply with the proposed provisions, 
existing high-voltage continuous mining machines would need to be 
retrofitted with

[[Page 17531]]

additional interlocked barriers and partitions to separate low- and 
medium-voltage from high-voltage components and circuits. One commenter 
stated that it is not the location of components that is the risk, but 
rather the access to energized high-voltage components. The commenter 
further stated that barriers, partitions, or the enclosure itself can 
prevent access. The primary purpose of proposed paragraph (a) is to 
prevent access to energized high-voltage components and circuits. In 
the final rule, MSHA has revised the proposal to clarify its intent to 
assure that existing equipment would not need retrofitting. The final 
rule permits high-voltage and low- and medium-voltage components and 
circuits in the same compartments if barriers are provided and covers 
are arranged so that testing and troubleshooting can be performed 
without exposing persons to any high-voltage conductors or parts. This 
change allows for flexibility in design and does not reduce safety for 
miners.
    Final paragraph (a), like the proposal, requires barriers and 
partitions to be constructed of grounded metal or nonconductive 
insulating board.
    One commenter expressed a preference for using barriers made of 
insulating boards rather than grounded metal, but stated that either is 
acceptable. MSHA agrees that use of either material would meet the 
requirements of final paragraph (a).
    Final paragraph (b) requires that each removable cover, barrier, or 
partition of a motor-starter enclosure that provides access to high-
voltage components be provided with at least two interlock switches 
that automatically de-energize the high-voltage components when the 
cover, barrier, or partition is removed.
    A commenter expressed concern with the proposed requirement for 
interlock switches on all barriers, partitions, and covers. The 
commenter requested that MSHA not require interlock switches except 
when the cover, barrier, or partition provides access to energized 
high-voltage circuits or parts.
    MSHA did not intend to require interlock switches on all barriers, 
partitions, and covers and has clarified the language in the final rule 
to require interlock switches only when there is direct access to high-
voltage circuits. Interlock switches protect miners from shock hazards 
by de-energizing high-voltage circuits when barriers, partitions, or 
covers are removed.
    Final paragraph (c), like the proposal, requires that circuit-
interrupting devices be designed and installed to prevent automatic re-
closure to protect miners from electrical shocks, fires, explosions, 
and unintentional machine movement. For example, a roof-collapse or 
equipment insulation failure can result in short-circuit or ground-
fault condition. This could result in the automatic re-closing of the 
circuit-interrupting device and pose a hazard to miners. MSHA received 
no comments on this proposal.
    Final paragraph (d), like the proposal, includes requirements for 
the grounding of the electrostatic shield for high-voltage transformers 
supplying control voltages on continuous mining machines.
    Final paragraph (d)(1), like the proposal, requires that the 
nominal control voltage not exceed 120 volts line-to-line. Limiting the 
control voltages to 120 volts line-to-line reduces the potential for 
electrocution of miners. This provision is consistent with granted 
PFMs. MSHA received no comments on this proposal.
    Final paragraph (d)(2), like the proposal, requires that control 
transformers with high-voltage primary windings in each high-voltage 
motor-starter enclosure, or that supply control power to multiple 
motor-starter enclosures, have an electrostatic (Faraday) shield 
installed between the primary and secondary windings. The purpose of 
the electrostatic shield is to isolate the high-voltage from lower-
voltage circuit. This protects miners from high-voltage shocks should a 
fault develop between the primary and secondary windings. Electrostatic 
shielding also prevents transients (sudden short-term changes in 
voltage and current) occurring on the primary circuit from being 
transferred to the secondary circuit. These transients can damage 
equipment and create the risk of a fire and electrical shock.
    Final paragraphs (d)(2)(i) and (d)(2)(ii) address requirements for 
grounding the electrostatic shield. If the transformer has an external 
grounding terminal, paragraph (d)(2)(i) requires the shield to be 
connected from the grounding terminal to the equipment ground by a 
minimum of a No. 12 American Wire Gauge (A.W.G.) grounding conductor. 
This requirement will assure proper current carrying capacity and 
mechanical strength of the grounding conductor.
    If the transformer does not have an external terminal, paragraph 
(d)(2)(ii) requires that the electrostatic shield be connected to the 
transformer frame by an internal conductor. This conductor, generally 
installed when the transformer is manufactured, is considered an 
extension of the shield and therefore may be smaller than a No. 12 
A.W.G. In this case, bolting the transformer frame to the equipment 
enclosure will provide the required path to ground, as long as an 
effective low impedance electrical connection is maintained. MSHA 
received no comments on these proposals.
    Final paragraph (e), like the proposal, addresses requirements for 
indicator light circuits. Final paragraph (e)(1) requires a grounded-
phase indicator light on any ungrounded, three-phase power circuit 
onboard the machine to alert the machine operator when a grounded-phase 
condition occurs. Ungrounded circuits include high-voltage transformers 
that power low- and medium-voltage circuits. The secondary windings of 
these transformers are connected in an ungrounded configuration. With 
ungrounded systems, the capacitive coupling between each phase 
conductor and ground can subject the ungrounded system to dangerous 
over-voltages resulting from intermittent ground faults. If a second 
phase is grounded, a short-circuit condition will occur and cause 
arcing between components. This could result in a methane-air 
explosion, cause failure of the enclosure, and expose miners to 
electrical shock. MSHA received a number of comments on this proposal.
    Some commenters stated that a grounded phase indicator light should 
be required on all high-voltage continuous mining machines. MSHA does 
not agree. This requirement is unnecessary when the three-phase power 
circuits onboard are grounded because the circuits are protected with 
ground-fault devices that automatically trip the circuit breaker at the 
power center. Currently, all 2,400-volt continuous mining machines have 
grounded-phase indicator light circuits because they have ungrounded 
power circuits onboard.
    Several commenters stated that lower voltage continuous mining 
machines and high-voltage shearing machines are not required to have a 
grounded-phase indicator light circuit and have operated many years 
without incident. They further stated that grounded-phase indictor 
light circuits are unnecessary and create a shock hazard for those who 
perform maintenance on the machine.
    In response, MSHA notes that lower voltage continuous mining 
machines and high-voltage shearing machines are designed differently 
from high-voltage continuous mining machines. Explosion-proof 
enclosures onboard low- and medium-voltage continuous mining machines 
and explosion-proof enclosures for high-voltage shearing machines are 
designed and tested to withstand arcing faults within the enclosure. On 
a high-voltage continuous

[[Page 17532]]

mining machine, however, only explosion-proof enclosures containing 
high-voltage switchgear are designed and tested to withstand internal 
arc faults. High-voltage continuous mining machines also have 
explosion-proof enclosures that do not contain high-voltage switchgear. 
These enclosures are not designed and tested to withstand high-energy 
arcing faults. Therefore, to prevent ignition hazards, the final rule 
requires indicator light circuits to assure that arcing does not occur 
and injure miners. Additionally, maintenance personnel are not exposed 
to shock hazards if they follow the troubleshooting and testing 
procedures specified in this final rule. MSHA believes that a greater 
hazard exists when a grounded-phase condition goes undetected.
    Final paragraph (e)(2), like the proposal, requires that the 
indicator light be installed so that the machine operator can readily 
observe it from any location where the continuous mining machine is 
normally operated. MSHA received no comments on this proposal.
    Final paragraph (e)(3), like the proposal, requires that the 
onboard ungrounded, three-phase power circuit have a test circuit for 
the grounded-phase indicator light circuit. It also requires that the 
test circuit be designed so that it can be activated without removing 
any enclosure covers and without creating a double-phase-to-ground 
fault. This requirement will assure proper operation of the indicator 
light circuit and that personnel conducting the test are not exposed to 
any hazard. MSHA received no comments on this proposal.
    Final paragraph (f) addresses the current carrying capacity, 
outside diameter, and the physical properties of high-voltage trailing 
cables. Unlike the proposal, the final rule does not incorporate by 
reference the Insulated Cable Engineer's Standards (ICEA) S-75-381/
National Electrical Manufacturer's Association (NEMA) Standard, NEMA WC 
58-1997, but rather includes a table for the outside diameters and 
ampacity ratings for high-voltage trailing cables. This table is 
referenced as Table 10 in Appendix I of 30 CFR Part 18, and is 
consistent with tables contained in the ICEA S-75-381/NEMA WC 58-1997. 
The purpose of the table is to standardize the ampacity and outer 
diameter of cables to ensure the interchangeability of trailing cables 
provided by different manufacturers.
    A commenter expressed concern that proposed paragraph (f) did not 
specifically limit trailing cable length. Existing Sec.  18.35(a)(5) 
specifies the maximum allowable lengths for trailing cables used to 
conduct electrical energy to production equipment, including continuous 
mining machines. For this reason, the Agency does not believe that it 
needs to limit trailing cable length in this provision.
    Final paragraph (f)(1), like the proposal, requires that trailing 
cables be constructed to include 100 percent semi-conductive tape 
shielding over each insulated power conductor. Final paragraph (f)(2) 
requires a grounded metallic braid shielding over each power conductor. 
The combination of semi-conductive tape and grounded metallic shielding 
around each power conductor provides symmetrical distribution of 
voltage stresses on the conductor insulation. Shielding also prevents 
transients on power systems. These provisions protect miners from shock 
and electrocution. MSHA received no comments on these proposals.
    Final paragraph (f)(3) requires that the cable include either a 
ground-check conductor not smaller than a No. 10 A.W.G., or a center 
ground-check conductor not smaller than a No. 16 A.W.G. stranded 
conductor. The term ``stranded'' has been added in the final rule to 
describe the No. 16 A.W.G. ground-check conductor for accuracy. The 
ground-check conductor is either located in the outer interstice of a 
trailing cable along with the grounding conductors or in the center of 
the trailing cable. Cables designed with a No. 16 A.W.G. center ground-
check conductor have been successfully used in high-voltage longwall 
applications for several years.
    A commenter indicated that the reference in the proposed preamble 
to the No. 16 A.W.G. ``stranded'' conductor describing the center 
ground-check conductor is technically incorrect, and suggested 
``special annular stranded with extensibility.'' MSHA does not agree. 
Cable manufacturers and ICEA/NEMA standards reference the center 
ground-check conductor as ``stranded.'' The terminology suggested by 
the commenter is a description of the quality of the No. 16 A.W.G. 
ground-check conductor and is consistent with the cable designs 
specified in the ICEA/NEMA standard.
    Final paragraph (f)(4), like the re-proposal, addresses the design 
and construction of high-voltage trailing cable jackets. MSHA received 
several comments on the proposal.
    Some commenters suggested that the final rule allow single-jacketed 
cables made of thermoplastic polyurethane (TPU) because of its high 
tensile strength and resistance to abrasion and tear. A commenter 
stated that the minimum tensile strengths for the single-jacketed and 
double-jacketed cables are 5,000 and 2,400 pounds per square inch, 
respectively; and tear strengths are 120 and 40 pounds per inch, 
respectively. The commenter also stated that the TPU material can be 
made in a color other than black, that TPU-jacketed trailing cables 
have been in use in the mining industry for 11 or 12 years, and that 
they have been used successfully on mining equipment such as shearing 
machines and medium-voltage continuous mining machines.
    Others stated that at least one granted PFM permitted the use of a 
TPU jacket as an alternative to the double-jacket requirement on two 
high-voltage continuous mining machines and on shuttle cars for over 
two years without any problems.
    Based on the comments, MSHA re-proposed paragraph (f)(4) to allow 
the option of using either a double-jacketed or a single-jacketed 
cable. The final rule contains requirements for both types of trailing 
cables.
    Final paragraph (f)(4)(i) requires that a double-jacketed cable, if 
used, consist of two reinforced layers of jacket material, with the 
inner layer a distinctive color from the outer layer. It also requires 
that black not be used for either layer. If used, a double-jacketed 
cable must have tear strength of more than 40 pounds per inch thickness 
and a tensile strength of more than 2,400 pounds per square inch.
    Final paragraph (f)(4)(ii) specifies the requirements for a single-
jacketed cable. If used, a single-jacketed cable must have tear 
strength of more than 100 pounds per inch thickness and a tensile 
strength of more than 4,000 pounds per square inch, and not be black in 
color. The final rule specifies the minimum values for the tear and 
tensile strength based on granted PFMs.
    In the re-proposal, MSHA requested comments on the minimum tear and 
tensile strength values for single-jacketed cables and received none.
    Final paragraph (g), like the proposal, requires manufacturers to 
provide safeguards against corona on all 4,160-volt circuits in 
explosion-proof enclosures.
    Corona is a luminous discharge that occurs around electric 
conductors that are subject to high electric stresses. Corona can cause 
premature breakdown of insulating materials in explosion-proof 
enclosures onboard the high-voltage continuous mining machine. This 
poses the risk of arcing and may result in explosion. Although corona 
usually does not present a hazard until a voltage of 8,000 volts is 
reached, safeguards should be taken at 4,160

[[Page 17533]]

volts, the maximum voltage permitted under Part 18. Safeguards 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. MSHA received no comments on this 
proposal.
    Final paragraph (h), like the proposal, 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. The requirement protects miners against explosion 
hazards that may arise from the effects of sustained high-voltage 
arcing faults. Arcing faults may significantly contribute to a pressure 
rise in an explosion-proof enclosure during an internal methane-air 
explosion. A pressure rise above the design limit of the enclosure can 
cause the explosion-proof enclosure to fail to contain the methane 
explosion. MSHA received no comments on the proposal.
    Final paragraph (i), like the proposal, prohibits high-voltage 
electrical components located in explosion-proof enclosures from being 
coplanar with a single-plane flame-arresting path. This provision 
prevents the heat or flame from an arc or methane explosion in an 
explosion-proof enclosure from igniting a methane-air mixture 
surrounding the enclosure by preventing conductor material particles 
from being expelled through the flame-arresting path. The possibility 
of this occurring with multi-plane flame-arresting path surfaces is 
non-existent because deflecting the path prevents ignitions by expelled 
particles. MSHA received no comments on this proposal.
    Final paragraph (j), like the proposal, requires that rigid 
insulation between high-voltage terminals (phase-to-phase or phase-to-
ground) be designed with creepage distances in accordance with the 
table specified in this section. The distances in the table provide 
adequate isolation to prevent a phase-to-phase or phase-to-ground fault 
that could cause a possible explosion. The required creepage distances 
are based on the phase-to-phase use voltage and the Comparative 
Tracking Index (CTI) of the insulation used. An appropriate method of 
determining the CTI of the electrical insulating material is described 
in the American Society for Testing and Materials Standard, ASTM D3638 
``Standard Test Method for Comparative Tracking Index of Electrical 
Insulating Materials.'' The creepage distances in the table are 
consistent with most commercially available high-voltage components to 
which this provision applies. MSHA received no comments on the 
proposal.
    Final paragraph (k), like the proposal, specifies minimum free 
distances (MFDs) in motor-starter enclosures. If the MFDs are below the 
values specified in the table, the enclosure could fail and cause an 
explosion. MFDs are distances between the wall or cover of an enclosure 
and uninsulated electrical conductors inside the enclosure. These MFDs 
are established to prevent wall or cover damage that might result from 
arcing.
    Final paragraph (k)(1), like the proposal, requires that values not 
specified in the table be calculated using a specific engineering 
formula. This formula is based on existing longwall requirements. Final 
paragraph (k)(2) requires that the MFD be increased by 1.5 inches for 
4,160-volt systems and by 0.7 inches for 2,400-volt systems when the 
adjacent wall area is the top of the enclosure. This increase in 
distance is necessary to account for the thermal effects of arcing due 
to heat rising within the enclosure. Final paragraph (k)(2) also 
addresses the use of a steel shield in conjunction with an aluminum 
wall or cover. Under these circumstances, the thickness of the steel 
shield is used to determine the MFD. MSHA received no comments on the 
proposal.
    Final paragraph (l), like the proposal, addresses static pressure 
testing of explosion-proof enclosures containing high-voltage 
switchgear. Final paragraph (l)(1) requires that, prior to performing 
the explosion tests, a static pressure test be performed on each 
prototype design of an explosion-proof enclosure housing high-voltage 
switchgear. It also establishes the static pressure testing and 
performance requirements for explosion-proof enclosures housing the 
high-voltage switchgear.
    Final paragraph (l)(2) requires that every explosion-proof 
enclosure containing high-voltage switchgear manufactured after the 
prototype was tested undergo a static pressure test or follow an MSHA-
accepted quality assurance procedure covering inspection of the 
enclosure. MSHA received no comments on this proposal.

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

Section 75.823 High-Voltage Continuous Mining Machines; Scope
    Final Sec.  75.823 describes the scope of this standard. The 
standard addresses requirements for use of high-voltage continuous 
mining machines of up to 2,400 volts in underground coal mines. Final 
Sec.  75.823 also defines the term ``qualified person'' to mean a 
person meeting the requirements specified in existing Sec.  75.153.
    MSHA received no specific comments on this proposal. However, 
several comments relating to machine voltage are relevant here. One 
commenter agreed with the proposed rule which would have allowed 
machines to operate at 4,160-volts. Other commenters opposed allowing 
the voltage to exceed 2,400-volts, the limit in granted PFMs. They 
stated that the industry has no experience with 4,160-volt continuous 
mining machines and that these machines are more dangerous than 2,400-
volt machines.
    The final rule limits the voltage of the continuous mining machines 
to 2,400 volts because of the Agency's lack of experience with 4,160-
volt continuous mining machines in coal mines. Part 18, however, allows 
for approval of equipment up to 4,160 volts. Mine operators seeking 
MSHA approval to use 4,160-volt continuous mining machines would have 
to file a petition for modification.
Section 75.824 Electrical Protection
    Final Sec.  75.824 establishes the electrical protection 
requirements for high-voltage continuous mining machines. Effective 
electrical protection reduces the likelihood of ignitions, fires, and 
electrical shocks. With the exception of (a)(2)(ii), this section is 
based on granted PFMs. This section of the final rule is the same as 
the proposed rule except that non-substantive changes have been made 
for clarity.
    Final paragraph (a) requires the use of an adequate circuit-
interrupting device capable of providing short-circuit, overload, 
ground-fault, and under-voltage protection. The purpose of a circuit-
interrupting device is to interrupt the circuit in which it is used 
without damage to itself when subjected to the maximum voltage and 
current of the system. Short-circuit and overload protection prevent 
damage to cables and motors that can result from arcing and 
overheating. Ground-fault protection minimizes the risk of shock and 
electrocution. Under-voltage protection prevents the unintentional 
movement of equipment which can place miners at risk when power is lost 
and then restored.
    Final paragraph (a)(1)(i) specifies the current setting for a 
short-circuit protective device. The device is required to be set at 
the lower of: (1) The setting specified in the approval documentation, 
or (2) 75 percent of the minimum available phase-to-phase

[[Page 17534]]

short-circuit current at the continuous mining machine.
    The approval documentation specifies the maximum allowable setting 
of the breaker required to protect the trailing cable. This setting 
takes into consideration the cable size and length, and the motor 
starting current. If 75 percent of the minimum available short-circuit 
current is less than the setting specified in the approval, the breaker 
setting will be based on that amount.
    One commenter suggested that MSHA eliminate the phrase ``whichever 
is less'' from the rule to allow the design of systems that could 
utilize smaller cables and reduce injuries from handling cables. MSHA 
does not agree with this commenter. If the size of the trailing cable 
used is different than the cable size specified in the approval 
documentation, the machine would not be permissible. Furthermore, 
eliminating the words ``whichever is less,'' would allow the mine 
operator to set the circuit-interrupting device at a value that may 
cause it not to trip. For example, if the mine operator chooses to set 
the circuit-interrupting device at 1,200 amps as required in the 
approval, and 75 percent of the minimum available short-circuit current 
is only 750 amps, the circuit-interrupting device would not trip.
    Final paragraph (a)(1)(ii) revises the proposed rule to allow the 
short-circuit device protecting the trailing cable to have an 
intentional time delay not exceeding 0.050 seconds. The purpose of 
permitting a time delay is to eliminate nuisance tripping during motor 
starting.
    Proposed paragraph (a)(1)(ii) required that the time delay not 
exceed the setting specified in the approval documentation or 0.050 
seconds, whichever is less. After further review, MSHA found that the 
approval documentation does not specify a time delay. No comments were 
received on this proposal.
    Final paragraph (a)(2) establishes requirements for ground-fault 
protection.
    Final paragraph (a)(2)(i) requires a neutral grounding resistor to 
limit ground-fault currents to not more than 0.5 amps. Neutral 
grounding resistors are used in resistance grounded systems to limit 
the level of ground-fault current in a circuit. The use of a 0.5 amps 
neutral grounding resistor in conjunction with the ground-fault device 
specified in final paragraph (a)(2)(ii) will provide additional 
protection to miners from shock and fire hazards. MSHA received no 
comments on this proposal.
    Final paragraph (a)(2)(ii) requires that the circuit extending to 
the continuous mining machine be protected by a ground-fault device set 
at not more than 0.125 amps. The provision also allows a maximum time 
delay of up to 0.050 seconds. The 0.125-amps limit is based on MSHA's 
experience and knowledge that sensitive ground-fault devices are 
commercially available and have been successfully used to detect 
ground-fault currents. The ground-fault device would have to operate 
within 0.050 seconds when exposed to 0.125 amps or more. MSHA received 
no comments on this proposal.
    Final paragraph (a)(2)(iii) requires a look-ahead circuit to detect 
a ground-fault condition and prevent the closing of a circuit-
interrupting device when the ground-fault exists in a circuit. 
Detection of the ground-fault condition prior to energizing the circuit 
will protect miners from the risk of electrical shock. Additionally, 
the final rule incorporates the best practice to prevent the circuit-
interrupting device from repeatedly closing when a ground-fault 
condition exists because that could create a second ground-fault which 
would result in a short-circuit condition. MSHA received no comments on 
this proposal.
    Final paragraph (a)(2)(iv) requires a backup ground-fault device to 
detect an open neutral grounding resistor under a ground-fault 
condition. This device will provide additional protection. Once an open 
neutral grounding resistor is detected, the backup device will cause 
the circuit-interrupting device to de-energize that circuit at 40 
percent of the voltage developed across the resistor. This value 
provides a safety factor. Additionally, this provision allows the 
backup device to have a maximum time-delay setting of 0.250 seconds. 
The time-delay setting is low enough to assure quick de-energization of 
the circuit when the neutral resistor opens and a ground-fault exists, 
while also allowing for selective tripping with the ground-fault 
protective device in final paragraph (a)(2)(ii).
    One commenter had several concerns about this provision. The 
commenter stated that there were numerous problems with the potential 
transformer and voltage relay monitoring method as a backup device, 
which was used in MSHA's example. The commenter stated that potential 
transformers are not able to detect rectified faults because of 
ferroresonance. The potential transformer and voltage relay monitoring 
method has been widely used in the industry and MSHA is not aware of 
any problems associated with it. It is important to note that the 
proposal did not require the use of a particular backup device to 
detect an open neutral grounding resistor. Although MSHA listed this 
method as an example of a backup device in the proposal as one means of 
compliance, the Agency noted that other alternatives were acceptable.
    The commenter also expressed concern that the proposal did not 
include a requirement for detecting a shorted resistor. The commenter 
stated that a shorted grounding resistor will not limit the voltage on 
the frame of portable equipment to 100 volts or less. The purpose of 
requiring a backup device is to detect a ground-fault condition when 
the neutral grounding resistor is open. The commenter's recommendation 
is not necessary because the ground-fault protection required in final 
paragraph (a)(2)(ii) will detect that condition and de-energize the 
circuit.
    This commenter also suggested that the proposal be changed to 
require de-energization of the circuit within a certain time if the 
neutral grounding resistor opens, such as within 30 to 60 seconds. MSHA 
is not aware of any device that monitors a shorted neutral grounding 
resistor, nor does the Agency see the need for such a device. For the 
reasons stated above, no changes have been made to this section, and 
the final rule is the same as the proposal.
    Final paragraph (a)(2)(v), like the proposal, requires a thermal 
device to detect an overheated neutral grounding resistor caused by 
sustained ground-fault current, and de-energize the incoming power. 
This device provides an added safety measure for miners.
    The rule also requires that the overtemperature rating or setting 
of the device be the lower of: (1) 50 percent of the maximum 
temperature rise of the neutral grounding resistor, or (2) 302 [deg]F 
(150 [deg]C). Exposure of the neutral grounding resistor to sustained 
ground-fault currents generates heat which can cause the resistor to 
fail in the open mode. Failure of the resistor in an open mode will not 
provide ground-fault protection and increases the risk of shock 
hazards. The overtemperature setting requirement assures that the 
affected circuit is quickly de-energized under a sustained fault. 
MSHA's experience is that the temperature settings specified are high 
enough to prevent nuisance tripping while providing safe operating 
temperatures. Under the final rule, thermal protection must not be 
dependent on control power. This requirement recognizes that the loss 
of control power would prevent the operation of the detection device. 
Thermal protection includes, but is not

[[Page 17535]]

limited to, current transformers and thermal relays, thermostats, and 
other devices that sense overtemperature. MSHA did not receive any 
comments on the proposal.
    Final paragraph (a)(2)(vi), like the proposal, requires a single 
window-type current transformer to encircle the three-phase conductors 
to activate the ground-fault device required in final paragraph 
(a)(2)(ii). It also prohibits the equipment grounding conductors from 
passing through the current transformer as this defeats operation of 
the ground-fault device and eliminates protection. Using the single-
window type current transformer in conjunction with a ground-fault 
relay provides ground-fault protection for the circuit extending from 
the power center to the continuous mining machine. MSHA received no 
comments on this proposal.
    Final paragraph (a)(2)(vii), like the proposal, requires a ground-
fault test circuit for each ground-fault device. This provision 
requires that the test circuit inject no more than 50 percent of the 
current rating of the neutral grounding resistor through the current 
transformer. The purpose of the test circuit is to verify that a 
ground-fault condition will cause the corresponding circuit-
interrupting device to open. MSHA received no comments on this 
proposal.
    Final paragraph (a)(3), like the proposal, requires that the under-
voltage device operate on a loss of voltage, de-energize the circuit, 
and prevent the equipment from automatically restarting. This provision 
is performance-oriented, which allows any under-voltage protective 
device that will operate on loss of voltage and prevent the circuit-
interrupting device from automatically closing upon restoration of 
power. This requirement will reduce pinning and crushing risks to 
miners in case the equipment automatically restarts upon restoration of 
power. MSHA received no comments on this proposal.
    Final paragraph (b), like the proposal, prohibits use of circuit-
interrupting devices that automatically re-close after opening. 
Automatic re-closure allows a circuit that has been de-energized to 
become automatically re-energized. This provision will prevent 
automatic re-closing under fault conditions. Typically, faults occur in 
trailing cables due to damage from roof falls or when equipment runs 
over the cables. If this occurs, the use of a circuit-interrupting 
device designed to re-close automatically could present a risk of 
electrical shock and fire. MSHA received no comments on this proposal.
    Final paragraph (c) requires a mine operator to take certain 
actions when a grounded-phase indicator light, if used, indicates a 
grounded-phase condition. Detection of a grounded-phase condition will 
reduce risks of electrical shock and arcing. The capacitive coupling 
between each phase conductor and ground can subject an ungrounded 
circuit to dangerous over-voltages from intermittent ground faults, 
which in turn can lead to arcing and insulation failure. Arcing can 
ignite methane and create a hazard to miners. Insulation failure can 
lead to another phase-to-ground failure and create a shock hazard.
    Final paragraphs (c)(1) and (c)(2) specify the actions to be taken 
when a grounded-phase condition is indicated. Under paragraph (c)(1), 
once the indicator light shows that a grounded-phase condition has 
occurred, the machine must immediately be moved to an area where the 
roof is supported. This will minimize miners' exposure to roof falls 
while the equipment is being repaired. Final paragraph (c)(2) requires 
that that the grounded-phase condition be located and corrected prior 
to placing the machine back into operation. This requirement will 
protect miners from risks of electrical shocks.
    MSHA received a number of comments concerning the indicator light 
circuit, and has addressed these comments in Sec.  18.54(e). Except for 
minor editorial changes, the final provision is the same as the 
proposed rule.
Section 75.825 Power Centers
    Final Sec.  75.825 revises the proposal, and addresses the 
requirements for power centers that supply high-voltage continuous 
mining machines. The final rule includes provisions for disconnecting 
switches and devices, barriers and covers, interlocks, emergency stop 
switches, grounding sticks, and caution labels. These provisions reduce 
risks of electrical shocks, fires, and explosions.
    Final paragraph (a), like the proposal, requires a main 
disconnecting switch in the power center that supplies power to the 
high-voltage continuous mining machines. The main disconnecting switch, 
when open, must de-energize the input power to all power transformers 
in the power center. This will provide a safe means of de-energizing 
high-voltage circuits in the power center without affecting the feed-
through circuits. MSHA received no comments on the proposal.
    Final paragraph (b), like the proposal, requires a disconnecting 
device for each circuit that powers a continuous mining machine. 
Disconnecting devices in power centers de-energize the power to the 
machine. Power must be de-energized prior to performing electrical 
work.
    MSHA received no comments on this provision. In the final rule, 
MSHA has added clarifying language and defined ``disconnecting device'' 
as either a disconnecting switch or cable coupler.
    Final paragraph (c), which was paragraph (c)(7) in the proposal, 
addresses labeling, design, and installation requirements for 
disconnecting switches specified in this final rule. This provision 
requires that each switch be labeled to clearly identify the circuit 
that it disconnects. MSHA's experience is that identifying the circuit 
being de-energized by the switch assures that the proper circuit is de-
energized, which protects miners from exposure to electrical hazards. 
The design and installation requirements are specified in paragraphs 
(c)(1) through (c)(6) of the final rule.
    Final paragraphs (c)(1) and (c)(2), like the proposal, require each 
disconnecting switch to have voltage and current ratings compatible 
with the circuits in which they are used. Improperly rated switches can 
cause overheating and arcing and may create a shock or fire hazard for 
miners. MSHA received no comments on these proposals.
    Final paragraph (c)(3), like the proposal, requires that the 
disconnecting switch be designed and installed so that one can visually 
verify, without removing any covers, that the contacts of the device 
are open. If miners had to remove the cover to verify that the contacts 
are open, they could be exposed to energized high-voltage circuits and 
electrical shock risks. MSHA received no comments on the proposal.
    Final paragraph (c)(4), like the proposal, requires the 
disconnecting switch to ground all power conductors on the ``load'' 
side when the switch is in the ``open and grounded'' position. It 
assures the discharge of any voltage caused by capacitance between the 
power conductors and ground. Grounding the circuit on the load side 
reduces the risk of shocks to miners who are working on the trailing 
cable or continuous mining machine. MSHA received no comments on the 
proposal.
    Final paragraph (c)(5), like the proposal, requires that each 
disconnecting switch be designed so that it can only be locked when in 
the ``open and grounded'' position. A disconnecting switch that locks 
in the closed position could delay opening the switch during an 
emergency. This provision, in conjunction with the

[[Page 17536]]

requirements of final Sec.  75.831, assures that the circuit will 
remain de-energized until work is completed. MSHA received no comments 
on the proposal.
    Final paragraph (c)(6), like the proposal, requires that the 
disconnecting switch safely interrupt the full-load current in the 
circuit. A switch that is not capable of safely interrupting the full-
load current could result in its destruction and injuries to miners 
from flash burns or flying parts.
    The final rule provides an alternative if the switch is not 
designed to interrupt the full-load current of the circuit. It requires 
that the switch be designed to cause the circuit-interrupting device to 
automatically de-energize the incoming power before the disconnecting 
switch opens the circuit. MSHA received no comments on this provision 
and the requirement of the final rule is identical to the proposed 
rule.
    Final paragraph (d) requires all compartments that provide access 
to high-voltage conductors or parts to have barriers or covers to 
prevent miners from coming into contact with energized circuits.
    A commenter was concerned that the proposed rule would require that 
both a cover and a barrier be installed. This was not MSHA's intent. 
MSHA has revised the final rule to clarify that barriers or covers, or 
both, can be used.
    Final paragraph (e), like the proposal, addresses the interlocking 
requirements between the control circuit and the main disconnecting 
switch.
    Final paragraph (e)(1) requires that the interlock allow the 
control circuit to be energized through an auxiliary switch in the 
``test'' position only when the main disconnecting switch is in the 
``open and grounded'' position. When the main disconnecting switch is 
in the ``open and grounded'' position, the power conductors on the load 
side of the disconnecting switch are de-energized and grounded. The 
interlocking feature assures that, before the auxiliary switch can be 
placed in the ``test'' position, the main disconnecting switch is open 
and grounded.
    Final paragraph (e)(2), like the proposal, requires that when the 
main disconnecting switch is ``closed,'' the control circuit can only 
be powered through an auxiliary switch that is in the ``normal'' 
position. These requirements will prevent energization of the high-
voltage circuits during testing and troubleshooting. MSHA received no 
comments on the proposed paragraph (e).
    Final paragraph (f), like the proposal, was derived from granted 
PFMs. It requires that each cover or removable barrier of any 
compartment providing access to energized high-voltage conductors or 
parts have at least two interlock switches for the purpose of de-
energizing exposed high-voltage conductors or parts when the cover or 
barrier is removed. While the granted PFMs did not specify how many 
interlock switches were required, the proposed rule required a minimum 
of two interlock switches as an added safety measure to protect miners 
against accidental contact with energized high-voltage circuits.
    In the proposal, MSHA specifically requested comments on whether to 
add an exception for troubleshooting control circuits. A commenter 
suggested that each removable cover or barrier be interlocked to remove 
all power in the compartment before entering it, except when testing 
and troubleshooting control circuits. The commenter gave an example of 
some power centers that are designed with a circuit breaker in a 
separate incoming high-voltage compartment where the circuit breaker 
will remove power in other compartments instead of removing the 
incoming power.
    MSHA believes that it is crucial to miners' safety that incoming 
power be de-energized when miners remove covers prior to performing 
electrical work. De-energizing incoming power rather than only the 
power in the compartment being accessed assures that miners will not be 
exposed to energized high-voltage circuits.
    This commenter further suggested that MSHA require a single 
interlock switch instead of the two switches required in the proposed 
rule. The commenter stated that interlock switches expose miners to 
hazards when they troubleshoot failed switches. As noted in the 
proposal, MSHA has found that interlock switches might not operate 
effectively after exposure to the mine environment. To protect miners 
against accidental contact with energized high-voltage circuits, the 
final rule, like the proposal, requires two interlock switches to 
assure that at least one switch will function.
    Another commenter stated that MSHA should not allow an exception 
for troubleshooting control circuits in the high-voltage compartments. 
MSHA believes that miners who troubleshoot and test energized circuits 
in accordance with the provisions in this and other existing rules, 
will be protected.
    MSHA has considered comments and revised the proposal to allow 
troubleshooting and testing energized circuits when the control circuit 
is powered through an auxiliary switch in the ``test'' position.
    Final paragraph (g), like the proposal, requires that an emergency 
stop switch be located on the outside of the power center. The switch 
will de-energize the incoming high-voltage if an emergency arises. This 
provision also requires that the switch be hard-wired to a fail-safe 
ground-wire monitor. In emergency situations, reliability of the stop-
switch is critical. MSHA received no comments on the proposal.
    Final paragraph (h), like the proposal, requires that the power 
center be equipped with a grounding stick to be used to discharge 
capacitors and circuits before electrical work is performed. The 
purpose of the grounding stick is to assure that all high-voltage 
capacitors are discharged and that all circuits and components are de-
energized before electrical work is performed.
    Capacitors are energy storage devices; they continue to be 
energized even after the circuit is de-energized. Although some 
capacitors are supplied with bleed-off resistors, these resistors can 
open and the capacitor will continue to be energized. A disconnecting 
switch blade may stick in the closed position with the switch in the 
open position. If this happens, one or more phases of the circuit would 
remain energized. Use of a grounding stick provides a last line of 
defense to assure that the person performing electrical work will not 
be exposed to energized high-voltage circuits.
    Although there is no generally accepted definition, MSHA considers 
a grounding stick to be a live line tool (hot stick) made of either 
wood or fiberglass with a grounding attachment bonded to a No. \1/0\ 
A.W.G. copper grounding conductor. To safely discharge the capacitors 
and parts, the grounding conductor would need to be permanently bonded 
to the power center frame.
    The final rule requires that the power center have a label that 
identifies the location of the grounding stick to assure that the 
person performing the electrical work can easily find it. The rule 
requires that the grounding stick be stored in a dry location to 
maintain its effectiveness.
    A commenter suggested that MSHA allow alternatives to the grounding 
stick to discharge capacitors or circuits. At this time, MSHA is not 
aware of any alternatives to the grounding stick. This provision will 
assure that energy storing components and circuits are discharged and 
de-energized before miners come in contact with them.
    Another commenter agreed with the grounding stick requirement, 
stating that it will allow the safe discharge of stored energy and 
assure that miners

[[Page 17537]]

will not be exposed to high-voltage circuits. This commenter suggested 
that MSHA require steps to assure that energy stored in the cable after 
it is disconnected is discharged. Final paragraph (c)(4) requires that 
the disconnecting device ground all power conductors of the trailing 
cable when the device is in the ``open and grounded'' position. 
Therefore, MSHA has addressed this concern.
    A third commenter stated that power centers that have a visual 
disconnect should not be required to have a grounding stick. Although 
the visual disconnecting device de-energizes the circuit it 
disconnects, it does not discharge capacitors and other circuits. 
Therefore, MSHA has not adopted the comment.
    Based on comments, MSHA has clarified that the intent of the 
grounding stick is to discharge capacitors and de-energize high-voltage 
circuits.
    Final paragraph (i), like the proposal, requires that all 
compartments that provide access to energized high-voltage conductors 
and parts display a caution label that warns miners against entering 
the compartment before de-energizing the incoming high-voltage. The 
label serves as a reminder to miners that the line side of a 
disconnecting switch remains energized when the switch is opened unless 
the incoming power to the switch is de-energized. The Agency did not 
receive any comments on the proposal.
Section 75.826 High-Voltage Trailing Cables
    Final Sec.  75.826, like the proposal, is derived from existing 
Sec. Sec.  75.804 and 18.35 and specifies the requirements for high-
voltage trailing cables.
    Final paragraph (a) requires that the high-voltage trailing cable 
meet the design requirements of existing Sec.  18.35 and the approval 
requirements of high-voltage continuous mining machines.
    Final paragraph (b) allows two sizes of ground-check conductors 
depending on the cable design. The first option allows the use of a 
ground-check conductor not smaller than a No. 10 A.W.G. as required in 
existing Sec.  75.804. This minimum size is required because the 
ground-check conductor is located on the periphery of the cable and is 
subjected to more flexing and bending, weakening the conductor and 
resulting in possible breakage or damage. As an alternative, the cable 
can have a ground-check conductor not smaller than the No. 16 A.W.G. 
located in the center of the cable. This design does not subject the 
ground-check conductor to the same stresses as the No. 10 A.W.G. when 
the cable is flexed. The main advantage of this alternative is the 
reduction of inter-machine arcing because the cable design will include 
three grounding conductors placed symmetrically. This cable design has 
been used successfully with high-voltage longwall equipment. It 
eliminates the need to petition for modification of Sec.  75.804(a) 
when the cable is designed with a center ground-check conductor smaller 
than No. 10 A.W.G. but not smaller than a No. 16 A.W.G. No comments 
were received on the proposed section.
Section 75.827 Guarding of Trailing Cables
    Final Sec.  75.827 addresses requirements for guarding trailing 
cables. It renumbers proposed Sec.  75.827(c) and (d) as final 
paragraphs (a) and (b).
    Proposed Sec.  75.827(a) would have required the high-voltage 
trailing cable to be supported on insulators or placed in an unused 
entry from the power center to the last open crosscut during advance 
mining, to within 150 feet outby any pillar workings during second 
mining, and to within 150 feet of the continuous mining machine when 
used in outby areas.
    Some commenters were concerned that supporting the cable on 
insulators may subject shuttle or ram car operators to injuries if the 
cable is supported at canopy height. They stated that in muddy 
conditions, shuttle or ram cars could slide into the coal ribs and 
cause the equipment to hit and damage the cable, exposing the equipment 
operators to possible arc burns and electrical shock. They also stated 
that by placing the cable on the floor, the machine tires and not the 
canopy would hit the cable, and any resulting hazard would occur away 
from the machine operator. Other commenters agreed with the proposed 
language requiring that the cables be supported on insulators but 
suggested that the cable be installed only when it is de-energized. 
Others suggested that the cable be installed on insulators at a minimum 
height of 6.5 feet and 7.5 feet.
    Commenters stated that an unused entry may not always be available 
to meet the proposed requirement to place the cable in an unused entry. 
After evaluating the comments, MSHA agrees that suspending the cable 
may be more of a hazard to miners than placing the cable on the mine 
floor. MSHA also agrees that an unused entry may not always be 
available. Therefore, the final rule does not contain the proposed 
requirements that the cable must be supported or placed in an unused 
entry.
    Proposed Sec.  75.827(b) permitted the temporary storage of cables 
on a sled or in a crosscut located between the power center and the 
last open crosscut. It required these storage locations to be 
barricaded and to have warning signs posted.
    One commenter stated that in many cases, allowing temporary storage 
of trailing cables at the locations in the proposal would encourage 
storage of cables in mining sections, posing a safety threat to miners. 
The commenter further stated that the proposal was not practical or 
safe. In response to comments, the final rule does not contain the 
requirement for temporary storage of cables.
    One commenter stated that the requirements of Sec.  75.827 are 
excessive because the cable leaving the power center is the safest 
cable on the section and should not be required to meet additional 
requirements. MSHA does not agree with this commenter because the cable 
is still susceptible to damage by mobile equipment. Consequently, 
guarding and protecting the cable from damage by mobile equipment are 
important safety measures for the protection of miners.
    Proposed Sec.  75.827(c), redesignated as final Sec.  75.827(a), 
addresses guarding of the trailing cable. Final paragraph (a)(1) 
specifies the locations where the high-voltage trailing cable must be 
guarded. These locations are: (1) From the power center cable coupler 
for a distance of 10 feet inby the power center; (2) from the entrance 
gland for a distance of 10 feet outby the last strain clamp on the 
continuous mining machine; and (3) any location where the cable could 
be damaged by moving equipment. These are locations where miners are 
likely to come in contact with the cable and where the cable could be 
damaged. To be effectively guarded, the cable must be fully covered, so 
that there is a physical barrier between the cables and miners. One 
commenter suggested that the trailing cable be guarded for 10 feet inby 
the power center. MSHA agrees that this is the location that miners are 
most likely to come in contact with the cable. In response to comments, 
the final rule requires that the cable be guarded for 10 feet inby the 
power center. The proposed requirement for guarding the trailing cable 
between the power center and the first cable insulator is not included 
in the final rule since insulators are not required.
    Final paragraph (a)(1)(ii) requires that the high-voltage trailing 
cable be guarded from the entrance gland for a distance of 10 feet 
outby the last strain clamp on the continuous mining machine. The 
proposal required guarding for a ``minimum'' of 10 feet. Some 
commenters suggested that this distance be increased from 10 feet to 35 
feet or more. The proposal would have

[[Page 17538]]

allowed guarding for a distance of 35 feet or more. However, requiring 
guarding for a distance longer than 10 feet, as suggested by the 
commenters, would preclude detection of a damaged cable in the guarded 
area because the final rule does not require removal of guarding when 
inspecting the cable. The final rule does not contain the term minimum 
and does not require guarding beyond 10 feet.
    Final paragraph (a)(1)(iii), like the proposal, requires guarding 
at any location where the cable could be damaged by moving equipment. 
MSHA received no comments on this proposal.
    Final paragraph (a)(2), like the proposal, requires that guarding 
be constructed of nonconductive flame-resistant material, or grounded 
metal. If a marking does not appear on the guarding to indicate that it 
is flame-resistant, MSHA will request documentation to substantiate 
that the material is flame-resistant. Metal and non-conductive guarding 
may be of a continuous length or overlapping shorter pieces. Shorter 
pieces of metal guarding must be bonded together to assure a continuous 
metallic path. MSHA received no comments on this proposal.
    Final paragraph (b) addresses requirements when equipment must 
cross any portion of the cable. It allows two alternatives for 
protecting the cable from mobile equipment: (1) Suspension of the cable 
from the mine roof; or (2) the use of commercially available cable 
crossovers. MSHA encourages mine operators to establish work practices 
that minimize the need for cable crossovers, such as placing the cable 
in locations where mobile equipment is not likely to travel.
    Final paragraphs (b)(2)(i) through (b)(2)(vii), like the proposal, 
specify minimum design requirements for cable crossovers. Cable 
crossovers are commercially available and are used throughout the 
industry to protect cables from mobile equipment damage. These minimum 
design requirements will assure that the largest piece of equipment 
used would be able to cross over the cable without damaging it. MSHA's 
experience is that cable crossovers provide effective protection when 
properly used. MSHA received no comments on the proposal. However, the 
phrase ``in or inby the last open crosscut'' is not included in the 
final rule and the requirement is not limited to any section of the 
mine.
Section 75.828 Trailing Cable Pulling
    Final Sec.  75.828 addresses procedures for pulling high-voltage 
trailing cable with equipment other than the continuous mining machine.
    In the proposal, Sec.  75.828 was titled ``Trailing Cable Handling 
and Pulling''. Proposed Sec.  75.828(a), dealing with handling 
energized cables, is renumbered Sec.  75.833(a) and addressed in the 
discussion of that provision. Except for editorial changes, final Sec.  
75.828 is identical to proposed Sec.  75.828(b). It requires that the 
mine operator de-energize the high-voltage trailing cable and follow 
manufacturer's procedures for pulling the cable. Cable manufacturers' 
recommendations usually include: The proper application of a rope or 
sling to pull the cable; minimum bending diameter; maximum length of 
trailing cable that can be safely pulled; and the number of corners 
that the cable can be pulled around. The purpose of this requirement is 
to prevent damage to the cable while it is being pulled. For example, 
when pulling a cable with ropes, if a loop smaller than the minimum 
bending diameter for the size of the trailing cable is created, the 
cable can be damaged.
    One commenter suggested that this proposed requirement be 
eliminated. Another stated that there was no safety benefit from 
requiring the trailing cable to be de-energized since the high-voltage 
trailing cable is significantly safer than other cables. These 
necessary requirements are included in the final rule as it has been 
MSHA's experience that pulling long lengths of cable around corners 
with shuttle cars or scoops may cause the ropes or slings to penetrate 
the cable and roll back the jacket, shielding, and insulation, thereby 
exposing energized conductors. If these conditions occur while the 
cable is energized, miners will be exposed to the risk of an electrical 
shock. De-energizing the trailing cable prior to pulling will assure 
that exposed conductors will not present shock hazards to miners.
Section 75.829 Tramming Continuous Mining Machines In and Out of the 
Mine and From Section to Section
    Final Sec.  75.829 addresses tramming continuous mining machines in 
and out of the mine or from one section to another, and testing 
required prior to tramming.
    Final paragraph (a) revises the proposal for clarity and sets forth 
procedures for tramming the continuous mining machine. It also requires 
that the applicable power sources used to tram the machine not be moved 
while energized as specified in existing Sec.  75.812.
    Final paragraph (a)(1), like the proposal, requires that when 
tramming the continuous mining machine the power source must not be 
located where permissible equipment is required. This provision is 
adapted from existing Sec.  75.500, which prohibits non-permissible 
equipment from being used in specific areas of the mine. Typically, 
power sources listed in Sec.  75.829(c) are not ``permissible'' and, 
therefore, must not be used in areas where permissible equipment is 
required. MSHA received no comments on this proposal.
    Final paragraph (a)(2) prohibits the mining machine from being used 
for mining while being trammed except when using a power source that is 
appropriate for this activity. Typically, the power sources used to 
tram the machine do not have the capacity to provide for mining or 
cutting functions. If mining or cutting were attempted while the 
machine was powered by sources other than a power center, overloading 
and loss of power could occur.
    Although MSHA received no comments on proposed Sec.  75.829(a)(2), 
the final rule clarified the proposal by specifying when a power center 
used for tramming is appropriate for mining and cutting.
    Final paragraph (a)(3), like the proposal, requires that low-, 
medium-, and high-voltage cables comply with the applicable provisions 
dealing with flame resistance qualities and design requirements of low, 
medium, and high voltages when using the power sources specified in 
Sec.  75.829(c). MSHA received no comments on this proposal.
    Final paragraph (a)(4), like the proposal, requires that the high-
voltage cable be mechanically secured onboard the continuous mining 
machine. This requirement applies to the high-voltage portable 
transformer specified in paragraph (c)(2) of this section. If the 
trailing cable does not fit on the machine, a shorter length of cable 
should be used to connect the diesel-generator output to the continuous 
mining machine. The purpose of this requirement is to prevent anyone 
from handling energized high-voltage cables and to minimize damage to 
the cable while tramming the continuous mining machine. MSHA received 
no comments on this proposal.
    Final paragraph (b), like the proposal, requires specific tests to 
be conducted prior to tramming. Final paragraph (b)(1) requires that 
ground-fault and ground-wire monitor tests be performed by a qualified 
person. The purpose of these tests is to assure proper operation of the 
ground-fault and ground-wire monitor. It is not the Agency's intent 
that these tests be performed after momentary or incidental stops 
during the tramming process. The testing

[[Page 17539]]

requirements assure that these devices operate properly to protect 
miners from electrical shocks. The final rule clarifies the meaning of 
a functional test. This provision also requires that corrective actions 
and recordkeeping resulting from these tests be performed in accordance 
with Sec. Sec.  75.832(f) and (g) of this final rule.
    The ground-fault test assures that the circuit will be de-energized 
if a ground-fault condition exists. Most manufacturers of power centers 
provide ground-fault test circuits so that the circuit can be tested 
without creating an actual ground-fault condition, which would expose 
miners to the risk of burns and shocks. The test will assure that the 
ground-wire monitor will de-energize the circuit if the ground-check or 
grounding circuit is opened. Manufacturers of ground-wire monitors 
provide a built-in test switch for this purpose. When low- and medium-
voltage power sources are used, a ground-wire monitor is required in 
accordance with Sec.  75.902. A ground-wire monitor is not required for 
the high-voltage power sources because these power sources use external 
bonding.
    One commenter suggested that a record be made only of the 
corrective actions and that such a record be kept on the machine with 
the date, time, and initials of the qualified person when the work is 
completed. MSHA's data and experience show that all records and 
certifications of tests and repairs are valuable tools for both mine 
operators and MSHA. Records and certifications can be used to determine 
trends with respect to equipment failure and/or design problems. They 
have also been useful sources of information during accident 
investigations. Records are required to be kept on the surface because 
they will be more readily accessible to mine personnel and inspectors. 
Therefore, final Sec.  75.829(b)(1) retains the requirements of the 
proposal.
    Final paragraph (b)(2), like the proposal, requires that prior to 
tramming the continuous mining machine, where applicable, a person 
designated by the operator must activate the test circuit for the 
grounded-phase detection circuit on the continuous mining machine. This 
test is applicable only if a grounded-phase detection circuit is 
required. The purpose of requiring this test is to assure that the 
detection circuit will successfully detect a grounded-phase condition. 
If the test indicates that the detection circuit is not functioning 
properly, corrective action must be taken in accordance with Sec.  
75.832(f) of the final rule. A record of this test is not required. 
MSHA received no comments on this proposal.
    Final paragraph (c) specifies the power sources, in addition to the 
power center, that may be used when the mining machine is trammed. 
Power sources specified in this section have been selected to minimize 
the need to handle energized high-voltage cables. It also specifies the 
requirements that different power sources, such as generators or 
stationary power supplies found at belt drives, must meet. These 
sources can provide: (1) Low or medium voltage to portable transformers 
that are either mounted on or attached to the high-voltage continuous 
mining machine; or (2) high-voltage power sources. The source is a 
generator set that includes a low- or medium-voltage diesel-generator 
and a step-up transformer that provides high voltage to the continuous 
mining machine.
    Final paragraph (c)(1), like the proposal, addresses the use of a 
medium-voltage power source that supplies 995 volts to the continuous 
mining machine. To use this type of power source, the machine circuitry 
would need to be rewired to allow the 995-volt trailing cable to 
energize the tram and hydraulic pump motor circuits. Figure 1 of the 
standard illustrates a high-voltage continuous mining machine using a 
995-volt power source. The 995 volts can be supplied by the mine's 
power system or a low- or medium-voltage diesel-generator set. If a 
low- or medium-voltage diesel-generator set is used as the power 
source, the generator set may be moved while energized in accordance 
with existing regulations. MSHA received no comments on the proposal.
    Final paragraph (c)(1)(i), like the proposal, prohibits back-
feeding the continuous mining machine with medium voltage to energize 
the high-voltage circuits. This provision will prevent the high-voltage 
motors from being powered by medium-voltage sources that do not meet 
necessary requirements. MSHA received no comments on this proposal.
    Final paragraph (c)(1)(ii) requires compliance with all applicable 
requirements for medium-voltage circuits in 30 CFR Part 75, such as 
overcurrent, ground-fault, under-voltage, and ground-wire monitors. 
MSHA received no comments on this proposal.
    Proposed Sec.  75.829(c)(1)(iii) is not included in the final rule. 
It would have prohibited moving the medium-voltage portable transformer 
while energized. This section was initially included in the proposed 
rule because it would not have been practical to move the energized 
portable transformer and comply with 30 CFR 75.516, which requires the 
power cable feeding the portable transformer to be supported on well-
insulated insulators. Additionally, if the portable transformer has a 
high-voltage primary winding that provides a medium-voltage output for 
tramming the continuous mining machine, the movement of the transformer 
would be prohibited by Sec.  75.812, unless the conditions specified in 
Sec.  75.812 are met. However, neither Sec. Sec.  75.516 nor 75.812 
prohibit movement of this equipment.
    Therefore, upon reconsideration, MSHA has decided not to include 
the proposed provision in the final rule to avoid any conflict with 
existing standards.
    Final paragraph (c)(2) addresses the use of step-up transformers to 
convert low or medium voltage to high voltage to power the continuous 
mining machine. Figure 2 of the standard illustrates this 
configuration. Unlike the proposal, the final rule does not include the 
term ``onboard'' to allow for other step-up transformers. The term 
``temporary,'' used in the proposed rule to define an ``onboard step-up 
transformer,'' is not used in the final rule.
    Final paragraph (c)(2)(i) requires that the trailing cable 
supplying low- or medium-voltage to the step-up transformer meet the 
applicable requirements of 30 CFR Part 75. For example, the trailing 
cable must meet the overcurrent, ground-fault, and under-voltage 
protection requirements for underground low- and medium-voltage 
alternating current circuits (Subpart J). The term ``input'' describing 
the trailing cable was removed, as unnecessary. This requirement 
remains unchanged from the proposed rule.
    Final paragraph (c)(2)(ii), like the proposal, requires that the 
high-voltage circuit output of the step-up transformer supplying power 
to the mining machine meet the applicable provisions of final Sec.  
75.824.
    Final paragraph (c)(2)(iii)(A) requires the step-up transformer to 
be securely mounted on either the continuous mining machine or a sled/
cart connected to the machine. This will minimize vibration that can 
lead to an internal ground fault or damage to the transformer. The 
proposal would have required the step-up transformer to be securely 
mounted onboard the continuous mining machine.
    Some commenters suggested that MSHA allow the installation of the 
transformer on a sled/cart connected by a tow-bar and in close 
proximity to the continuous mining machine. MSHA agrees that this 
alternative provides

[[Page 17540]]

effective protection and has revised the proposal accordingly.
    Final paragraph (c)(2)(iii)(B), like the proposal, requires that 
the frame of the transformer be bonded to the frame of the continuous 
mining machine and the metallic shell of each cable coupler by a No. 1/
0 A.W.G. or larger conductor, and connected to the incoming ground 
conductor of the trailing cable. These grounding requirements assure a 
low impedance grounding path from the transformer to the outby power 
source should a ground-fault condition occur. MSHA received no comments 
on the proposal.
    Final paragraph (c)(2)(iii)(C), like the proposal, requires that 
each of the transformer enclosure covers be equipped with at least two 
interlock switches and that an external emergency stop switch be 
provided to de-energize the input power to the step-up transformer when 
activated in emergency situations. MSHA received no comments on the 
proposal and the final rule includes clarifying changes.
    Proposed paragraph (c)(3) is not included in the final rule in 
response to comments.
    One commenter objected to addressing high-voltage diesel-powered 
generators in the proposed rule, stating that the equipment was not 
relevant to the rulemaking and should be dealt with in a separate 
rulemaking. The commenter requested that MSHA conduct public hearings 
on the issue and suggested that MSHA include these requirements in the 
rulemaking on low- and medium-voltage diesel-powered electrical 
generators if necessary. In response to comments, the final rule does 
not include the high-voltage diesel generator option.
Section 75.830 Splicing and Repair of Trailing Cables
    Final Sec.  75.830 defines and addresses requirements for splices 
and repairs of trailing cables.
    Final paragraph (a) is derived from granted PFMs and addresses 
requirements for persons performing splices and repairs. It also 
specifies the manner in which the trailing cable must be spliced or 
repaired to assure that miners are not exposed to shock and burn 
hazards.
    Commenters stated that the proposal did not distinguish between a 
splice and a repair, and suggested that MSHA define these terms. In 
response, MSHA has defined the terms in final paragraphs (a)(1) and 
(a)(2) based on existing Sec.  7.402 and granted PFMs.
    Another commenter stated that MSHA should use the language from the 
Program Policy Manual relating to the existing standard for temporary 
splice of trailing cable (Sec.  75.603) to identify whether cable 
damage requires a splice or repair. This existing standard is not 
applicable here because the proposed rule addressed permanent cable 
repairs. The final rule does not use temporary or permanent. It 
requires the use of an MSHA-approved kit, which precludes the use of 
temporary splices.
    Final paragraph (a)(3)(i), like the proposal, requires that cable 
splicing and repair be performed only by a qualified person who is 
trained in cable splicing and repair of high-voltage cables. From 
MSHA's experience, hands-on training provides effective training. These 
requirements will assure that the individual performing cable splicing 
and repair understands the construction of the cable, the purpose of 
every component, and the hazards associated with failure to replace 
each component with a component similar to the original.
    Some commenters suggested that the proposal be revised to allow 
splices to be made under the direction of a qualified person. MSHA has 
not incorporated this suggestion because a qualified person has the 
knowledge and experience to make an effective splice that will protect 
miners from electrical shocks. MSHA is concerned that a person who is 
not qualified may not have the knowledge, training, or experience to 
perform splicing and repairs safely.
    Final paragraph (a)(3)(ii), like the proposal, requires that 
splicing and repairs be made in a workman-like manner. The quality of 
workmanship is vital to maintaining the same level of protection to 
miners as that provided by the original cable. MSHA received no 
comments on the proposal.
    Final paragraph (a)(3)(iii), like the proposal, requires that 
splices and repairs of trailing cables meet the requirements of 
existing Sec.  75.810. This existing standard requires that the spliced 
or repaired cable be mechanically strong, provide the same flexibility 
and conductivity as the original cable, be insulated and sealed to 
exclude moisture, preserve the cable's flame-resistance quality, and 
have good bonding to the outer jacket. MSHA received no comments on 
this proposal.
    Final paragraph (a)(3)(iv) revises proposed Sec.  75.830(b) by 
deleting the reference to permanent cable repair and requires that the 
trailing cable be repaired using an MSHA-approved splice kit that 
contains specific instructions.
    MSHA prohibited the use of a permanent tape-type splice in granted 
PFMs. The final rule does not prohibit this type of splice. Tape-type 
splices can be used to make an effective splice when proper procedures 
are followed. MSHA did not allow them in granted PFMs because the 
splice materials were often used improperly and allowed moisture to 
enter the splice. Moisture degrades the insulation and ultimately 
creates a risk of electrical shock. Instead of prohibiting all tape-
type splices, the final rule requires that all splices be made with an 
MSHA-approved splice kit. The approved kits contain materials and 
appropriate instructions on the proper methods for making a splice. The 
kit includes tape that is self-vulcanizing so it will exclude moisture 
when applied as instructed, thereby preventing the risk of electrical 
shock.
    MSHA received several comments concerning tape-type splices. Some 
commenters suggested that only vulcanized splices be used because 
moisture cannot be kept out of tape splices. These commenters stated 
that although tape-type splices are good when first made, after 
dragging the cable the tape splices become damaged. MSHA does not agree 
that only vulcanized splices can be effective. If a splice is made in 
accordance with the instructions included in the MSHA-approved high-
voltage splice kit, the splice should be effective and exclude 
moisture.
    Another commenter stated that electricians need more training on 
cable splicing and repair because not everyone reads the instructions 
provided in the kits. MSHA agrees and, in response, the final rule 
includes a new requirement for specialized training for persons who 
perform maintenance on high-voltage mining machines which includes the 
cable.
    Final Sec.  75.830(b) limits the number of splices in a certain 
portion of the trailing cable. Final Sec.  75.830(b)(1), as in the 
proposal, prohibits splicing of the high-voltage trailing cable within 
35 feet of the continuous mining machine.
    Some commenters suggested that splicing should be prohibited within 
50 to 60 feet from the continuous mining machine. MSHA's experience 
with low- and medium-voltage equipment is that the portion of the cable 
within 35 feet of the continuous mining machine is subjected to more 
strains, stresses, and cable handling than the rest of the cable. The 
probability that a miner will be shocked by an inadequate splice is 
greatest within this portion of the cable due to weakened and damaged 
cable.
    Several commenters stated that the number of splices should be 
limited because cable splicing causes the resistance of the cable to go 
up. MSHA asked commenters during public

[[Page 17541]]

hearings for suggestions on a reasonable limit for the number of 
splices. No number was suggested. Final paragraph (b)(2) limits to four 
(4) the splices in the portion of the trailing cable that extends from 
the continuous mining machine outby for a distance of 300 feet. Granted 
PFMs contained a 4-splice limitation. Based on Agency experience with 
PFMs, the final rule includes this limit.
Section 75.831 Electrical Work; Troubleshooting and Testing
    Final Sec.  75.831 includes requirements for performing electrical 
work, including troubleshooting and testing. It contains editorial 
changes for clarity.
    Final paragraph (a) requires that prior to performing electrical 
work, other than troubleshooting and testing, on the trailing cable or 
continuous mining machine, a qualified person must de-energize the 
trailing cable in accordance with either paragraph (a)(1) or (a)(2). 
De-energization is usually accomplished by opening the circuit-
interrupting device. The qualified person must follow the required work 
procedures to prevent inadvertent re-energization. These procedures are 
important to assure that miners are not exposed to potential shock, 
fire, or other hazards when performing electrical work.
    Final paragraphs (a)(1) and (a)(2) specify the two lock-out and 
tagging procedures. Depending on the power center design, a 
disconnecting switch or a cable coupler (plug and receptacle) would be 
used to lock-out and tag the trailing cable. Final paragraph (a)(1) 
specifies work procedures if a disconnecting switch is used on the 
output circuit of the power center supplying power to the continuous 
mining machine. If a disconnecting switch is used, final paragraph 
(a)(1)(i) requires the switch to be opened to provide visual evidence 
that the output is de-energized, grounded, and locked out and tagged in 
the open and grounded position. This allows the cable coupler plug to 
remain connected to the power receptacle. No comments were received on 
this proposal.
    Final paragraph (a)(1)(ii), like the proposal, requires the plug 
and receptacle to be locked together and tagged. This requirement will 
assure that the cable coupler plug cannot be disconnected from the 
receptacle and connected to a spare circuit. When this procedure is 
used, connection to a grounding receptacle is unnecessary because 
opening the disconnecting switch grounds the power conductors of the 
high-voltage trailing cable.
    MSHA understands that some mine operators prefer not to disconnect 
high-voltage couplers since this may lead to problems when re-
energizing the circuit. The main problem with disconnecting high-
voltage couplers is the risk of contaminating the couplers' insulation 
with dust. Using a disconnecting switch to ground and isolate power 
from the trailing cable and continuous mining machine would eliminate 
the need to remove the cable coupler plug from the receptacle.
    One commenter suggested that the proposal be revised to allow other 
means of locking-out and tagging, such as requiring all spare circuit 
visual disconnects to be locked-out and tagged. This suggestion may 
require the person performing the work to carry more keys and locks 
because there may be more than one spare circuit and each must be 
locked. Also, MSHA believes that most of the plugs and receptacles are 
designed with means to lock them together.
    Final paragraph (a)(2), like the proposal, addresses the use of a 
cable coupler as a disconnecting device. After power has been removed, 
final paragraph (a)(2)(i) requires the plug to be disconnected from the 
receptacle and connected to a grounding receptacle. The grounding 
receptacle, which is mounted on the power center, will cause all power 
conductors of the cable to be grounded to the power center frame. 
Connecting the plug to the grounding receptacle assures that no voltage 
will be present in the cable conductors. MSHA received no comments on 
this proposal.
    Final paragraph (a)(2)(ii) requires the plug and grounding 
receptacle to be locked together and tagged. Tagging will alert miners 
that work is being done on the circuit, and the lock will prevent the 
circuit from being re-energized and ungrounded while work is being 
performed. These requirements will prevent shock hazards to miners 
while performing electrical work. MSHA received no comments on this 
proposal.
    Final paragraph (a)(2)(iii) requires that a dust cover be placed 
over the power receptacle to protect it from becoming contaminated by 
dust when the trailing cable is disconnected. Dust is a conducting 
medium and can create ground faults. The dust cover will also prevent 
miners from contacting energized parts of the receptacle. MSHA received 
no comments on this proposal.
    Final paragraph (b) addresses all troubleshooting requirements. It 
contains only minor clarifying changes from the proposal. It requires 
that during troubleshooting and testing, the de-energized cable may be 
disconnected from the grounding receptacle only for that period of time 
necessary to locate the defective condition. Generally, when the cable 
is disconnected from the power receptacle, it is connected to the 
grounding receptacle. It also requires that prior to troubleshooting 
and testing the trailing cable, a qualified person must follow one of 
the lock-out and tagging procedures specified in paragraphs (b)(1) and 
(b)(2). Following these procedures prevents inadvertent re-energization 
of the circuits being tested and protects miners from shock, fire, or 
other hazards.
    Final paragraphs (b)(1) and (b)(2), like the proposal, address 
lock-out and tagging procedures based on the design of the power 
center. These procedures are the same as discussed in paragraph (a) of 
this section.
    One commenter suggested that since the high-voltage trailing cable 
is not subject to accumulation of static charges, as in the case of a 
surface high-voltage line which is subject to wind and other sources of 
charge buildup, the Agency should not require constant grounding. MSHA 
does not agree and, consistent with existing rules, the final rule 
contains grounding requirements to assure the safety of personnel 
performing electrical work on high-voltage circuits.
    Final paragraph (c), re-numbered from proposed paragraph (d), 
addresses limitations on troubleshooting and testing. It is derived 
from granted PFMs and existing troubleshooting requirements for 
longwalls. The final rule recognizes that it may be necessary for 
circuits or equipment to remain energized for troubleshooting and 
testing, such as when taking voltage and current readings to identify a 
problem. It contains conditions under which this can be done.
    Final paragraph (c)(1), like the proposal, limits troubleshooting 
and testing of energized circuits to low- and medium-voltage systems 
because troubleshooting and testing energized circuits is known to be 
inherently hazardous work. Further, there are no adequate equipment and 
insulation ratings for testing energized high-voltage circuits and 
equipment. MSHA received no comments on this proposal.
    Final paragraph (c)(2), like the proposal, permits troubleshooting 
and testing of energized circuits only for the purpose of determining 
voltages and currents, including evaluation of waveforms or other 
electrical diagnostic testing. MSHA received no comments on this 
proposal.
    Final paragraph (c)(3), like the proposed (d)(3), requires that 
troubleshooting and testing of energized circuits be performed only by 
a qualified person. This requirement assures that the person conducting 
the

[[Page 17542]]

testing is aware of the hazards associated with these tests. The 
requirement for wearing properly rated gloves has been moved to final 
paragraph (c)(4). MSHA received no comments on this proposal.
    Final paragraph (c)(4) requires that the qualified person wear 
protective gloves when the voltage of the circuit is 40 volts or more. 
It also specifies the types of gloves to be used for different 
voltages. Based on MSHA's experience and electrical accident data, the 
Agency has concluded that 40 volts is the lowest voltage level that is 
likely to cause electrocution. The final rule requires gloves to 
protect miners who might inadvertently contact energized circuits 
during troubleshooting and testing.
    Dry work gloves or rubber insulating gloves with leather 
protectors, in good condition, i.e., free of holes, etc., can be used 
when troubleshooting 40-volt to 120-volt circuits nominal. Normally, 
the nominal control voltage for mining equipment is 120 volts. If 
miners are testing intrinsically safe circuits, dry gloves can be used 
for circuits that exceed 120 volts nominal. When the circuit is not 
intrinsically safe, rubber insulating gloves with leather protectors 
rated for at least the nominal voltage of the circuit and equipment are 
required to be used on circuits that exceed 120 volts nominal. 
Typically, mining equipment is rated as 220, 480, 995 volts and higher. 
Commercially available rubber insulating gloves are rated for 1,000 
volts but are not rated for each of these voltages. Therefore, when 
testing or troubleshooting low- and medium-voltage circuits, 1,000-volt 
rated gloves must be used. MSHA received no comments on this proposal.
    Final paragraph (d), re-numbered from proposed paragraph (e), 
specifies the work procedures to be followed when performing electrical 
work, other than troubleshooting and testing, in any compartment of the 
power center. These procedures will assure that miners are not exposed 
to potential shock, fire, or other hazards when performing electrical 
work.
    Final paragraph (d)(1), re-numbered from proposed (e)(1), requires 
that affected circuits be de-energized in accordance with existing de-
energization requirements (see Sec.  75.509). MSHA received no comments 
on the proposal.
    Final paragraph (d)(2), re-numbered from proposed paragraphs (e)(2) 
and (4), requires that a qualified person open the corresponding 
disconnecting switch and lock it out and tag it to isolate the circuit. 
MSHA received no comments on the proposal.
    Final paragraph (d)(3), re-numbered from proposed (e)(3), requires 
that a qualified person visually verify that the contacts of the 
disconnecting switch are open and grounded. To verify, the qualified 
person views the position of the contacts through a window. Opening the 
disconnecting switch grounds the high-voltage conductors. Grounding the 
conductors protects the miner working on a circuit from exposure to 
energized high-voltage circuits which reduces the risk of electrical 
shock and electrocution. MSHA received no comments on the proposal.
    Final paragraph (d)(4), re-numbered from proposed paragraph (e)(5), 
requires that all high-voltage capacitors and circuits in the power 
center be discharged prior to performing electrical work. Because 
capacitors are energy storage devices, they may continue to hold a 
charge even after the disconnecting switch is opened and the circuit is 
de-energized. Therefore, to assure that miners are not exposed to shock 
hazards, capacitors and circuits must be discharged before performing 
work. MSHA received no comments on the proposal.
    Final paragraph (e), re-numbered from proposed paragraph (f), 
requires that when more than one qualified person is working on the 
same circuit or equipment, each person must install their own lock and 
tag on the circuit or equipment on which work is being performed. It 
also requires that each lock and tag be removed by the individual who 
installed them. Limiting removal of the lock to the person who 
installed it will prevent accidental re-energization of equipment or 
circuits before all persons have completed their work.
    MSHA's accident investigation experience reveals that failure to 
lock out and tag circuits and equipment prior to performing maintenance 
is the root cause of many accidents. This finding is supported in both 
the National Safety Council's Data Sheet 237 Revision B, ``Methods of 
Locking Out Electrical Switches'' (1971) and the National Fire 
Protection Association's NFPA 70E ``Standard for Electrical Safety 
Requirements for Employee Workplaces'' (2000 Edition). If persons are 
required to place and remove their own locks, they will be more aware 
of and responsible for their own safety as well as safety of others. 
Following these procedures, miners will take the steps necessary to 
assure proper de-energization. This requirement reduces the risk of 
error due to lack of communication or inadvertent re-energization. MSHA 
received no comments on this proposal.
    Final paragraph (e)(2), like proposed paragraph (f)(2), includes 
requirements for removing locks and tags. If the person who installed 
the lock and tag is not available, the mine operator can authorize a 
qualified person to remove that person's lock and tag. In this case, 
the mine operator must notify the person who installed the lock and tag 
that they have been removed. MSHA received no comments on this 
proposal.
Section 75.832 Frequency of Examinations; Recordkeeping
    Final Sec.  75.832 includes non-substantive editorial changes for 
clarity. It specifies the frequency of testing certain equipment and 
circuits, and the requirements for creating and maintaining adequate 
records. Unlike granted PFMs that required some tests to be done 
weekly, the final rule requires those tests to be conducted at least 
every 7 days. Frequent examination and testing of the trailing cable 
and the high-voltage continuous mining machine, as well as testing of 
the ground-fault test circuit and ground-wire monitor circuit, is 
necessary because moving this equipment increases the likelihood of 
component failure and break down. MSHA's enforcement experience with 
existing weekly examination and testing requirements indicates that the 
actual frequency between examinations and tests is sometimes as long as 
13 days. By changing the requirement to testing every 7 days, MSHA will 
avoid prolonged periods between tests and examinations.
    Final paragraph (a) requires that a qualified person examine the 
high-voltage continuous mining machine at least once every 7 days to 
verify that electrical protection, equipment grounding, permissibility, 
cable insulation, and control devices are properly installed and 
maintained. The purpose of the examination is to assure that the 
equipment is operating safely. The examination will also advance 
miners' safety and minimize their exposure to fire, electric shock, 
ignition, or operational hazards.
    Final paragraph (b) requires that, at least once every 7 days and 
prior to tramming the machine, a qualified person activate the ground-
fault test circuit to verify that it will cause the corresponding 
circuit-interrupting device to open. Activating the ground-fault test 
circuit verifies that the ground-fault protection circuit is operating 
properly. Failure of the ground-fault circuit to function properly when 
a

[[Page 17543]]

ground fault exists would expose miners to shock hazards.
    Final paragraph (c), like the proposal, requires that, at least 
once every 7 days and prior to tramming the machine, a qualified person 
test the ground-wire monitor circuit to verify that it will cause the 
corresponding circuit-interrupting device to open. Testing of a ground-
wire monitor circuit normally requires activation of a test switch.
    MSHA received a number of comments on this proposal. Some 
commenters suggested that the 7-day examination requirement be changed 
to a weekly examination. They stated that the 7-day requirement will be 
confused with other electrical examinations performed on a weekly or 
monthly basis and recommended that, for consistency purposes, testing 
should be done on a weekly basis. Other commenters supported the 7-day 
requirement, stating that the weekly requirement can provide a gap of 
13 days between tests. MSHA agrees and the final rule includes the 7-
day requirement for testing and examination.
    Final paragraph (d) addresses inspection of the high-voltage 
trailing cable.
    Final paragraph (d)(1) requires that once each day, during the 
shift that the continuous mining machine is first energized, a 
qualified person de-energize and inspect the entire length of cable 
from the power center to the machine. This inspection must include all 
areas of the cable where guarding is required, the outer jacket 
repairs, and splices for damage or deterioration. The cable inspection 
does not require removal of the guarding but rather, requires assuring 
that the guarding is provided where required. In response to comments, 
MSHA has replaced production day that was in the proposal with the more 
clarifying phrase ``during the shift that the continuous mining machine 
is first energized''.
    Final paragraph (d)(2) requires that at the beginning of each shift 
that the continuous mining machine is energized, a person designated by 
the mine operator de-energize and visually inspect the high-voltage 
trailing cable from the mining machine: (1) To the last open crosscut; 
(2) to within 150 feet of the working place during retreat or second 
mining; or (3) up to 150 feet of the machine when it is used in outby 
areas for cutting overcasts, underpasses, sumps, etc. The inspection 
must include an examination of the outer jacket of the cable for 
damage. The specified locations are areas where the trailing cable is 
most likely to be damaged by mobile equipment. Visual inspection will 
assure the integrity of the cable and increase miners' safety.
    MSHA received a number of comments on the proposed provisions 
relating to trailing cable inspections. One commenter suggested that 
the proposed requirements be deleted due to the superior design and 
construction of high-voltage trailing cables. Although MSHA agrees that 
the high-voltage trailing cable design and construction is superior to 
low- and medium-voltage cable designs, the Agency continues to believe 
that the requirements in the final rule are necessary to assure 
integrity of the cable while in use.
    Others recommended changing the proposal from each production shift 
to each shift. They stated that such a change would be necessary in 
order to include idle shifts during which equipment is moved for 
section setup and maintenance. Another commenter suggested that MSHA 
change the proposal to allow for hot seat change-outs. Some commenters 
disagreed with this suggestion because this change would allow 
inspections to be made at the end of the shift and could result in a 
damaged cable remaining undetected for eight hours.
    MSHA agrees with the suggestion to inspect the cable at the 
beginning of each shift the machine is energized, which would include 
idle shifts. MSHA believes that it is important to examine the trailing 
cable in all shifts where the machine is energized to detect any damage 
and has revised the proposal accordingly.
    Another commenter objected to the proposed provision requiring the 
high-voltage trailing cable to be de-energized, suggesting instead that 
the miner wear high-voltage gloves when handling the energized cable. 
MSHA does not agree because when visually examining the high-voltage 
trailing cable, the miner may need to handle, move, or bend the cable. 
Handling, moving, or bending a damaged energized cable can result in an 
internal short-circuit and subsequent arc-flash injuries to the miner. 
Using high-voltage gloves to handle a damaged energized cable would not 
protect miners from arc-flash injuries. Therefore, it is necessary to 
de-energize the cable prior to the examination.
    Final paragraph (e), like the proposal, is derived from granted 
PFMs and requires that at the beginning of each production shift, a 
person designated by the operator must test the grounded-phase 
detection circuit on the high-voltage continuous mining machine. This 
provision will assure that the detection circuit functions properly and 
that it will detect a grounded-phase condition. If the detection 
circuit is defective, a grounded-phase condition will remain undetected 
and miners will be exposed to the risk of electrical shock. MSHA 
received no comments on the proposal.
    Final paragraph (f), like the proposal, requires equipment to be 
removed from service or repaired when any examinations or tests reveal 
damage that could lead to a risk of fire, electric shock, ignition, or 
operational hazard. This provision will assure that equipment that may 
pose a danger to miners is not used until the hazardous condition is 
corrected. For example, if examination of a trailing cable reveals an 
exposed conductor, miners would be at risk of potential fire, 
electrical shock, and methane gas ignition when the cable is energized. 
MSHA received no comments on this proposal.
    Final paragraph (g) specifies the recordkeeping requirements for 
the examinations and tests in the final rule and is consistent with 
existing recordkeeping requirements. Records and certifications of 
tests and repairs are valuable tools for mine operators. Records and 
certifications are used by MSHA to identify trends in equipment failure 
and design problems so that the Agency can disseminate necessary best 
practice information to the mining community.
    Final paragraph (g)(1)(i), like the proposal, requires that the 
person who examines and tests the equipment certify by signature and 
date that the tests and examinations have been conducted. Only the 
person conducting the examinations and tests can provide the 
certification because that person would have direct knowledge of the 
test results.
    Final paragraph (g)(1)(ii) requires that a record be kept of any 
unsafe conditions found by the individual who conducted the tests 
because that person would have direct knowledge of the unsafe 
conditions. Unlike the proposal, which did not identify who must record 
corrective action, final paragraph (g)(2) specifies that the individual 
who takes any corrective action must be the one to record that action. 
The clarification is important because the person conducting the tests 
may not be the one who takes the corrective action.
    Final paragraphs (g)(3) and (g)(4) are new provisions added in 
response to comments. Final paragraph (g)(3) requires that records must 
be countersigned by the mine foreman or equivalent mine official by the 
end of their next regularly scheduled working shift. Final paragraph 
(g)(4) requires that records be maintained either in a secure book that 
is not susceptible to alteration or electronically in a computer system

[[Page 17544]]

that is also secure and not susceptible to alteration.
    Some commenters suggested that mine management share the 
responsibility of assuring that records are properly documented and 
stored. In so doing, these commenters raised the fact that the proposal 
did not require records to be countersigned and that they have made 
this suggestion on several occasions during previous rulemakings. MSHA 
has re-evaluated this issue. In the preamble to the proposed rule, MSHA 
stated that the Agency accepts certification only from the person who 
examines and tests the equipment because that person will have 
knowledge of the results of the examination and tests. MSHA 
reconsidered its position and the final rule requires countersigning of 
records by a foreman or equivalent. In making this change, the Agency 
determined that countersigning of records by a foreman or equivalent 
will help to assure accuracy of the records. Additionally, as mentioned 
earlier, records are an important tool in maintaining miners' health 
and safety. The countersigning requirement will provide important 
corroboration of this vital action.
    One commenter requested that the recordkeeping requirement be more 
specific. This commenter requested clarification on alternate methods 
of recordkeeping, specifically questioning electronic signatures for 
electronic records.
    The final rule requires that examination, testing, and repair 
records for mine equipment must not be susceptible to alteration. MSHA 
recognizes that electronic storage of records is becoming a more 
valuable alternative for the mining industry. In response to comments, 
the final rule includes a new provision to require that records be 
maintained either in a secure book that is not susceptible to 
alteration or electronically in a computer system that is also secure 
and not susceptible to alteration. MSHA defines the phrase ``secure and 
not susceptible to alteration'' to mean that the stored record, 
including signatures, cannot be tampered with or modified. Examples of 
books that are considered secure and not susceptible to alteration 
include, but are not limited to, record books that are currently 
approved by state mine safety agencies and permanently bound books. 
Examples of books that are not considered secure and are susceptible to 
alteration include loose leaf binders and spiral note books. An example 
of an acceptable electronic record storage that is secure would be a 
record stored in a ``write once, read many'' drive. MSHA believes that 
electronic records meeting these criteria are practical and reliable as 
traditional records.
    Final paragraph (g)(5), like the proposal, requires that 
certifications and records, including those in electronic form, be kept 
for at least one year and be made available at the mine for inspection 
by authorized representatives of the Secretary and representatives of 
miners. MSHA received no comments on this proposal.
Section 75.833 Handling High-Voltage Trailing Cables
    Final Sec.  75.833 addresses the requirements for handling 
energized trailing cables. It requires that energized trailing cable 
not be handled unless high-voltage insulating gloves or insulated cable 
handling tools are used.
    Based on comments received on the proposed rule, the re-proposal 
contained the option of providing high-voltage insulating gloves, which 
include both the rubber gloves and the leather outer protector gloves, 
or insulated cable handling tools. MSHA received two comments on the 
re-proposal. Both commenters suggested that MSHA should not require the 
use of insulating high-voltage gloves because the high-voltage trailing 
cable is safer than current trailing cables already permitted for use 
without gloves. Under the final rule, gloves are not required if cable 
handling tools are used.
    Some commenters on the proposal recommended that personal 
protective equipment (PPE) be required in addition to the cable 
handling tools. MSHA considered this comment and decided that because 
PPE is not tested to a nationally-recognized standard, it may not 
provide protection to miners. For that reason the final rule does not 
require PPE.
    Final paragraph (a), like the re-proposal, prohibits handling 
energized trailing cables unless high-voltage insulating gloves or 
insulating cable handling tools are used.
    Final paragraph (b), like the re-proposal, requires that mine 
operators make either the insulating gloves or cable handling tools 
available for miners to use.
    Final paragraph (c), like the re-proposal, addresses the 
requirements for insulating gloves and cable handling tools. Final 
paragraph (c)(1) addresses the design requirements for rubber gloves 
and incorporates by reference the American Society for Testing and 
Materials (ASTM) publication ASTM F496-02a, ``Standard Specification 
for In-Service Care of Insulating Gloves and Sleeves'' (2002). Final 
paragraph (c)(2) requires that the rubber gloves be air-tested to 
assure their effectiveness. Final paragraph (c)(3) requires that both 
the leather protector and the rubber insulating glove be visually 
examined before each use. Final paragraph (c)(4) requires that damaged 
rubber gloves be removed from service or destroyed, and that the 
leather protector be maintained in good condition or replaced.
    Final paragraph (d), like the re-proposal, addresses the 
requirements for insulated cable handling tools. Final paragraph (d)(1) 
requires that insulated cable handling tools be rated and maintained to 
withstand at least 7,500 volts to assure that the handling tools 
provide at least the same level of protection to miners as the 
insulating high-voltage gloves.
    Final paragraph (d)(2) requires that insulated cable handling tools 
be designed and manufactured for cable handling to protect miners from 
shock hazards. Examples of insulated cable handling tools are hooks, 
slings, and tongs, when designed and manufactured for cable handling.
    Final paragraph (d)(3) requires that the insulated cable handling 
tools be visually examined before each use for signs of damage or 
defects.
    Final paragraph (d)(4) requires that damaged or defective insulated 
cable handling tools be removed from the underground area of the mine 
or destroyed to assure that they are not available to use.
Section 75.834 Training
    Final Sec.  75.834 is new and addresses training requirements based 
on comments received on the proposal. One commenter stated that it is 
important to train miners on safety practices where new technologies 
are utilized and requested that specific training be required for those 
who test and repair high-voltage cables. MSHA originally believed that 
part 48 provides sufficient training requirements. Upon consideration, 
the final rule contains specific training requirements that are 
consistent with the provisions in granted PFMs. It also requires that 
the specialized training be specified in the part 48 plans.
    Final paragraph (a) requires that miners who perform maintenance on 
high-voltage continuous mining machines be trained in high-voltage 
safety, testing, and repair and maintenance procedures. Final paragraph 
(b) requires that miners who work in the vicinity of high-voltage 
continuous mining machines or who move the high-voltage equipment or 
cables also be trained in high-voltage safety procedures and 
precautions. MSHA's experience is that not only miners who work on 
equipment are

[[Page 17545]]

exposed to hazards, but also miners in the vicinity.
Section 75.1002 Installation of Electric Equipment and Conductors; 
Permissibility
    Existing Sec.  75.1002 addresses requirements for conductors and 
cables used in or in by the last open crosscut as well as electrical 
equipment, conductors and cables used within 150 feet of pillar 
workings. Final Sec.  75.1002 allows the use of shielded, high-voltage 
cables that supply power to permissible continuous mining machines in 
underground coal mines. No comments were received on this proposal.

IV. Executive Order 12866: Regulatory Planning and Review

    Executive Order (E.O.) 12866, as amended, requires that regulatory 
agencies assess both the costs and benefits of intended regulations. To 
comply with Executive Order 12866, MSHA has prepared a Regulatory 
Economic Analysis (REA) for the final rule. The REA contains supporting 
data and explanations for the summary materials presented in sections 
IV through VII of this preamble, including the covered mining industry, 
benefits and costs, feasibility, small business impact, and information 
collection requirements. The REA is located on MSHA's Web site at 
http://www.msha.gov/rea.HTM#final. A copy of the REA can be obtained 
from MSHA's Office of Standards, Regulations and Variances. MSHA has 
determined that the final rule will not have an annual effect of $100 
million or more on the economy and, therefore, it is not an 
economically ``significant regulatory action'' pursuant to section 3(f) 
of E.O. 12866.

A. Population at Risk

    The final rule applies to all underground coal mines in the United 
States. Based on MSHA data, there were 583 underground coal mines 
reporting production, employing 44,456 miners, operating in the U.S. in 
2008.

B. Benefits

    The final rule will reduce the potential for electrical-related 
fatalities and injuries when using high-voltage continuous mining 
machines due to: Better design and construction criteria; improved 
ground-fault protection; handling of lighter cables; and increased 
safety requirements for work practices. These design and work practice 
requirements offer greater protection against electrical shock, cable 
overheating, fire hazards, unsafe work and repair practices, and back 
injuries and other sprains caused by handling trailing cables. These 
benefits are described in more detail in Chapter III of the REA 
associated with this rulemaking.

C. Compliance Costs

    MSHA estimates that the final rule will result in total yearly net 
compliance cost of approximately $50,100 for all the underground 
operators that use high-voltage continuous mining machines. MSHA 
estimates that for all underground coal mine operators that use high-
voltage continuous mining machines with 20-500 employees, yearly costs 
will be approximately $85,875 and yearly cost savings will be 
approximately $45,200, which results in a net cost of approximately 
$40,675. For all underground coal mine operators using high-voltage 
continuous mining machines with 501+ employees, MSHA estimates yearly 
costs of approximately $16,225 and yearly cost savings of approximately 
$6,800, which results in a net cost of $9,425. For a complete breakdown 
of the compliance costs and savings of the final rule, see Chapter IV 
of the REA associated with this rulemaking.

V. Feasibility

    MSHA has concluded that the requirements of the final rule are 
technologically and economically feasible.

A. Technological Feasibility

    High-voltage continuous mining machines have been used to produce 
coal in underground coal mines since 1997. Underground coal mine 
operators that use high-voltage continuous mining machines are 
currently following most of the provisions of the final rule through 
conditions set forth in their granted Petitions for Modification 
(PFMs). Any requirements in the final rule that are different from 
those currently being followed in granted PFMs will not make the 
implementation of the final rule technologically infeasible for 
underground coal mine operators who choose to use high-voltage 
continuous mining machines for extracting coal. MSHA therefore 
concludes that the final rule is technologically feasible.

B. Economic Feasibility

    MSHA has traditionally used a revenue screening test--whether the 
yearly compliance costs of a regulation are less than 1 percent of 
revenues, or are negative (i.e., provide net cost savings)--to 
establish presumptively that compliance with the regulation is 
economically feasible for the mining industry. As estimated in the REA 
that accompanies this final rule, the underground coal mining industry 
will incur a net yearly compliance cost of approximately $50,100 versus 
annual revenue of approximately $18.4 billion per year. On this basis, 
the Agency concludes that the rule is economically feasible.

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

    Pursuant to the Regulatory Flexibility Act (RFA) of 1980, as 
amended by the Small Business Regulatory Enforcement Fairness Act 
(SBREFA), MSHA has analyzed the impact of the final rule on small 
businesses. Based on that analysis, MSHA has notified the Chief Counsel 
for Advocacy, Small Business Administration, and made the certification 
under the Regulatory Flexibility Act at 5 U.S.C. 605(b) that the final 
rule will not have a significant economic impact on a substantial 
number of small entities. The factual basis for this certification is 
presented in full in Chapter V of the REA and in summary form below.

A. Definition of a Small Mine

    Under the RFA, in analyzing the impact of the final rule on small 
entities, MSHA must use the Small Business Administration (SBA) 
definition for a small entity or, after consultation with the SBA 
Office of Advocacy, establish an alternative definition for the mining 
industry by publishing that definition in the Federal Register for 
notice and comment. MSHA has not taken such an action and hence is 
required to use the SBA definition. The SBA defines a small entity in 
the mining industry as an establishment with 500 or fewer employees.
    In addition to examining small entities as defined by SBA, MSHA has 
also looked at the impact of this final rule on underground coal mines 
with fewer than 20 employees, which MSHA and the mining community have 
traditionally referred to as ``small mines.'' These small mines differ 
from larger mines not only in the number of employees, but also in 
economies of scale in material produced, in the type and amount of 
production equipment, and in supply inventory. Therefore, the cost of 
complying with MSHA's final rule and the impact of the final rule on 
small mines will also be different. It is for this reason that small 
mines are of special concern to MSHA.
    Although the final rule does apply to mine operators with fewer 
than 20 employees that choose to use high-

[[Page 17546]]

voltage continuous mining machines, MSHA's experience has been that no 
underground coal mine operator with fewer than 20 employees has ever 
requested a PFM to use high-voltage continuous mining machines. MSHA 
has analyzed the economic impact of the final rule on all underground 
coal mine operators with 500 or fewer employees, which conforms to the 
requirements of the RFA. The Agency concludes that it can certify that 
the final rule will not have a significant economic impact on a 
substantial number of small entities that are covered by this final 
rule.

B. Factual Basis for Certification

    Using SBA's definition of a small mine operator, the estimated 
yearly net compliance cost of the final rule on small underground coal 
mine operators is approximately $40,675. The estimated yearly net 
compliance cost is less than one percent of the estimated annual 
revenues of approximately $14.5 billion for small underground coal mine 
operators with 500 or fewer employees.
    Based on this analysis, MSHA has determined that the final rule 
will not have a significant economic impact on a substantial number of 
small underground coal mine operators with 500 or fewer employees. MSHA 
has certified these findings to the SBA. The factual basis for this 
certification is discussed in Chapter V of the REA associated with this 
final rule.

VII. Paperwork Reduction Act of 1995

    As a result of this final rule there will be: (1) An elimination of 
burden hours and related cost approved under OMB control numbers 1219-
0065 and (2) burden hours in the Information Collection Request (ICR) 
that accompanies this final rule. The burden hours and related cost for 
these two items are discussed below. For a more detailed explanation of 
how the burden hours and related cost for the two items were 
determined, see Chapter VII of the REA associated with this final rule.

A. Elimination of Burden Hours

    As a result of this final rule, mine operators will no longer need 
a PFM of existing 30 CFR 75.1002 to use a high-voltage continuous 
mining machine. Existing OMB control number 1219-0065 includes annual 
burden hours and cost related to the time it takes mine operators to 
prepare and file petitions with MSHA, including petitions to use a 
high-voltage continuous mining machine. As a result of this rulemaking, 
the burden hours and cost approved under OMB control number 1219-0065 
that relate to the time it takes operators to prepare and file 
petitions need to be reduced to reflect the fact that petitions to use 
a high-voltage continuous mining machine will no longer be needed. 
Therefore, the burden hours and cost in OMB control number 1219-0065 
should be reduced by approximately 48 hours and $3,700 annually.

B. Burden Hours

    The final rule will impose approximately 819 first-year burden 
hours and related cost of $50,200 on underground coal mine operators 
using high-voltage continuous mining machines. Of the 819 first-year 
burden hours, 12 hours and related costs of $700 are associated with 
conducting a ground-fault and ground-wire monitor circuit test prior to 
tramming the high-voltage continuous mining machine as required by 
final Sec.  75.829. In addition, 242 hours and related cost of $9,450 
are associated with tagging requirements that are required by final 
Sec.  75.831. Also, 565 hours and related cost of $40,050 are 
associated with final Sec.  75.832(c), which requires a ground-wire 
monitor circuit test, and final Sec.  75.832(g), which requires 
countersigning of records concerning examinations and tests specified 
in final Sec.  75.832(a), (b), and (c).
    The following final requirements do not have burden hours 
associated with them. Final Sec.  75.825(i) requires that all 
compartments providing access to energized high-voltage conductors and 
parts display a caution label to warn miners against entering the 
compartment(s) before de-energizing incoming high-voltage circuits. 
This requirement is not a paperwork burden to mine operators because it 
is currently a normal business practice of manufacturers to place such 
warning labels on the compartments noted above.
    Final Sec.  75.832(a) and (b) require that examinations or tests be 
conducted at least once every seven days, and final Sec.  75.832(g) 
requires that a record be made of these examinations or tests. 
Paragraph (a) requires an examination of the high-voltage continuous 
mining machine. Paragraph (b) requires a test of the ground-fault test 
circuit. The examinations required by final Sec.  75.832(a) and (b) are 
already being conducted as part of a larger weekly examination of 
electrical equipment required under existing Sec.  75.512 (electrical 
equipment; examination, testing and maintenance). Existing Sec.  75.512 
also requires that records be made of these examinations and tests. 
Since the burden for conducting examinations and tests required by 
final Sec.  75.832(a) and (b) and making records of them is already 
accounted for under existing Sec.  75.512 (which is approved under OMB 
control number 1219-0116), such activity is not included in the ICR 
accompanying this final rule. However, the countersigning of these 
records is not part of any existing requirement, and is, therefore, 
accounted for in the ICR that accompanies this rulemaking.

C. Details

    The information collection package has been submitted to the Office 
of Management and Budget (OMB) for review under 44 U.S.C. 3504(h) of 
the Paperwork Reduction Act of 1995, as amended. A copy of the 
information collection package can be obtained from the Department of 
Labor by email request to [email protected] or by phone request at 
202-693-4129.

VIII. Other Regulatory Considerations

A. The Unfunded Mandates Reform Act of 1995

    MSHA has reviewed the final rule under the Unfunded Mandates Reform 
Act of 1995 (2 U.S.C. 1501 et seq.). MSHA has determined that this 
final rule does not include any federal mandate that may result in 
increased expenditures by State, local, or tribal governments; nor will 
it increase private sector expenditures by more than $100 million in 
any one year or significantly or uniquely affect small governments. 
Accordingly, the Unfunded Mandates Reform Act of 1995 (2 U.S.C. 1501 et 
seq.) requires no further Agency action or analysis.

B. Executive Order 13132: Federalism

    The final rule does not have ``federalism implications'' because it 
will not ``have substantial direct effects on the States, on the 
relationship between the national government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government.'' Accordingly, under E.O. 13132, no further Agency action 
or analysis is required.

C. The Treasury and General Government Appropriations Act of 1999: 
Assessment of Federal Regulations and Policies on Families

    Section 654 of the Treasury and General Government Appropriations 
Act of 1999 (5 U.S.C. 601 note) requires agencies to assess the impact 
of Agency action on family well-being. MSHA has determined that the 
final rule will have no effect on family stability or safety, marital 
commitment, parental rights and authority, or income or poverty of 
families and children. The final rule impacts only the underground coal 
mine industry. Accordingly, MSHA

[[Page 17547]]

certifies that the final rule will not impact family well-being.

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

    This final rule does not implement a policy with takings 
implications. Accordingly, under E.O. 12630, no further Agency action 
or analysis is required.

E. Executive Order 12988: Civil Justice Reform

    The final rule was written to provide a clear legal standard for 
affected conduct and was carefully reviewed to eliminate drafting 
errors and ambiguities, so as to minimize litigation and undue burden 
on the Federal court system. Accordingly, the final rule will meet the 
applicable standards provided in section 3 of E.O. 12988, Civil Justice 
Reform.

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

    The final rule will have no adverse impact on children. 
Accordingly, under E.O. 13045, no further Agency action or analysis is 
required.

G. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    The final rule does not have ``tribal implications'' because it 
will not ``have substantial direct effects on one or more Indian 
tribes, on the relationship between the Federal government and Indian 
tribes, or on the distribution of power and responsibilities between 
the Federal government and Indian tribes.'' Accordingly, under E.O. 
13175, no further Agency action or analysis is required.

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

    Executive Order 13211 requires agencies to publish a statement of 
energy effects when a rule has a significant energy action that 
adversely affects energy supply, distribution or use. MSHA has reviewed 
this final rule for its energy effects because the final rule applies 
to the underground mining sector. Because this final rule will result 
in yearly net compliance cost of approximately $50,100 to the 
underground coal mining industry, relative to annual revenues of $18.4 
billion in 2008, MSHA has concluded that it is not a significant energy 
action because it is not likely to have a significant adverse effect on 
the supply, distribution, or use of energy. Accordingly, under this 
analysis, no further Agency action or analysis is required.

List of Subjects in 30 CFR Parts 18 and 75

    Coal mining, Incorporation by reference, Mine safety and health, 
Reporting and recordkeeping requirements, Underground mining.

    Dated: March 29, 2010.
Joseph A. Main,
Assistant Secretary of Labor for Mine Safety and Health.

0
For the reasons set out in the preamble and under the authority of the 
Mine Safety and Health Act of 1977, as amended, Chapter I of Title 30, 
Code of Federal Regulations, Parts 18 and 75 are amended as follows:

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

0
1. The authority citation for part 18 continues to read as follows:

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


0
2. Add Sec.  18.54 to subpart B to read as follows:


Sec.  18.54  High-voltage continuous mining machines.

    (a) Separation of high-voltage components from lower voltage 
components. In each motor-starter enclosure, barriers, partitions, and 
covers must be provided and arranged so that personnel can test and 
troubleshoot low- and medium-voltage circuits without being exposed to 
energized high-voltage circuits. Barriers or partitions must be 
constructed of grounded metal or nonconductive insulating board.
    (b) Interlock switches. Each removable cover, barrier, or partition 
of a compartment in the motor-starter enclosure providing direct access 
to high-voltage components must be equipped with at least two interlock 
switches arranged to automatically de-energize the high-voltage 
components within that compartment when the cover, barrier, or 
partition is removed.
    (c) Circuit-interrupting devices. Circuit-interrupting devices must 
be designed and installed to prevent automatic re-closure.
    (d) Transformers supplying control voltages.
    (1) Transformers supplying control voltages must not exceed 120 
volts line to line.
    (2) Transformers with high-voltage primary windings that supply 
control voltages must incorporate a grounded electrostatic (Faraday) 
shield between the primary and secondary windings. Grounding of the 
shield must be as follows:
    (i) Transformers with an external grounding terminal must have the 
shield grounded by a minimum of No. 12 A.W.G. grounding conductor 
extending from the grounding terminal to the equipment ground.
    (ii) Transformers with no external grounding terminal must have the 
shield grounded internally through the transformer frame to the 
equipment ground.
    (e) Onboard ungrounded, three-phase power circuit. A continuous 
mining machine designed with an onboard ungrounded, three-phase power 
circuit must:
    (1) Be equipped with a light that will indicate a grounded-phase 
condition;
    (2) Have the indicator light installed so that it can be observed 
by the operator from any location where the continuous mining machine 
is normally operated; and
    (3) Have a test circuit for the grounded-phase indicator light 
circuit to assure that the circuit is operating properly. The test 
circuit must be designed so that, when activated, it does not require 
removal of any electrical enclosure cover or create a double-phase-to-
ground fault.
    (f) High-voltage trailing cable(s). High-voltage trailing cable(s) 
must conform to the ampacity and outer dimensions specified in Table 10 
of Appendix I to Subpart D of this part. In addition, the cable must be 
constructed with:
    (1) 100 percent semi-conductive tape shielding over each insulated 
power conductor;
    (2) A grounded metallic braid shielding over each insulated power 
conductor;
    (3) A ground-check conductor not smaller than a No. 10 A.W.G.; or 
if a center ground-check conductor is used, not smaller than a No. 16 
A.W.G. stranded conductor; and
    (4) Either a double-jacketed or single-jacketed cable as follows:
    (i) Double jacket. A double-jacketed cable consisting of reinforced 
outer and inner protective layers. The inner layer must be a 
distinctive color from the outer layer. The color black must not be 
used for either protective layer. The tear strength for each layer must 
be more than 40 pounds per inch thickness and the tensile strength must 
be more than 2,400 pounds per square inch.
    (ii) Single jacket. A single-jacketed cable consisting of one 
protective layer. The tear strength must be more than 100 pounds per 
inch thickness, and the

[[Page 17548]]

tensile strength must be more than 4,000 pounds per square inch. The 
cable jacket must not be black in color.
    (g) Safeguards against corona. Safeguards against corona must be 
provided on all 4,160-voltage circuits in explosion-proof enclosures.
    (h) Explosion-proof enclosure design. The maximum pressure rise 
within an explosion-proof enclosure containing high-voltage switchgear 
must be limited to 0.83 times the design pressure.
    (i) Location of high-voltage electrical components near flame 
paths. High-voltage electrical components located in high-voltage 
explosion-proof enclosures must not be coplanar with a single plane 
flame-arresting path.
    (j) Minimum creepage distances. Rigid insulation between high-
voltage terminals (Phase-to-Phase or Phase-to-Ground) must be designed 
with creepage distances in accordance with the following table:

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                    Minimum creepage distances (inches) for comparative tracking index
                                                                    Points of                                 (CTI) range \1\
                    Phase-to-phase voltage                           measure     -----------------------------------------------------------------------
                                                                                     CTI >= 500     380 <= CTI < 500  175 <= CTI < 380      CTI < 175
--------------------------------------------------------------------------------------------------------------------------------------------------------
2,400.........................................................               0-0              1.50              1.95              2.40              2.90
                                                                             0-G              1.00              1.25              1.55              1.85
4,160.........................................................               0-0              2.40              3.15              3.90              4.65
                                                                             0-G              1.50              1.95              2.40              2.90
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Assumes that all insulation is rated for the applied voltage or higher.

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

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

    (1) For values not included in the table, the following formulas, 
on which the table is based, may be used to determine the minimum free 
distance.
    (i) Steel Wall/Cover:
    [GRAPHIC] [TIFF OMITTED] TR06AP10.000
    
    (ii) Aluminum Wall/Cover:
    [GRAPHIC] [TIFF OMITTED] TR06AP10.001
    

Where ``C'' is 1.4 for 2,400 volt systems or 3.0 for 4,160 volt 
systems; ``Isc'' is the three-phase, short-circuit current 
in amperes of the system; ``t'' is the clearing time in seconds of the 
outby circuit-interrupting device; and ``d'' is the thickness in inches 
of the metal wall/cover adjacent to an area of potential arcing.
    (2) The minimum free distance must be increased by 1.5 inches for 
4,160 volt systems and 0.7 inches for 2,400 volt systems when the 
adjacent wall area is the top of the enclosure. If a steel shield is 
mounted in conjunction with an aluminum wall or cover, the thickness of 
the steel shield is used to determine the minimum free distances.
    (l) Static pressure testing of explosion-proof enclosures 
containing high-voltage switchgear.
    (1) Prototype enclosures. The following static pressure test must 
be performed on each prototype design of an explosion-proof enclosure 
containing high-voltage switchgear prior to the explosion tests.

[[Page 17549]]

    (i) Test procedure.
    (A) The enclosure must be internally pressurized to at least the 
design pressure, maintaining the pressure for a minimum of 10 seconds.
    (B) Following the pressure hold, the pressure must be removed and 
the pressurizing agent removed from the enclosure.
    (ii) Acceptable performance.
    (A) During pressurization, the enclosure must not exhibit:
    (1) Leakage through welds or casting; or
    (2) Rupture of any part that affects the explosion-proof integrity 
of the enclosure.
    (B) Following removal of the pressurizing agents, the enclosure 
must not exhibit:
    (1) Cracks in welds visible to the naked eye;
    (2) Permanent deformation exceeding 0.040 inches per linear foot; 
or
    (3) Excessive clearances along flame-arresting paths following 
retightening of fastenings, as necessary.
    (2) Enclosures for production. Every explosion-proof enclosure 
containing high-voltage switchgear manufactured after the prototype was 
tested must undergo one of the following tests or procedures:
    (i) The static pressure test specified in paragraph (l)(1)(i) of 
this section; or
    (ii) An MSHA-accepted quality assurance procedure covering 
inspection of the enclosure.
    (A) The quality assurance procedure must include a detailed check 
of parts against the drawings to determine that--
    (1) The parts and the drawings coincide; and
    (2) The requirements stated in part 18 have been followed with 
respect to materials, dimensions, configuration and workmanship.
    (B) [Reserved]

Appendix I to Subpart D [Amended]

0
3. Add Table 10 to Appendix I to Subpart D of Part 18 to read as 
follows:
* * * * *

                     Table 10--High Voltage Trailing Cable Ampacities and Outside Diameters
----------------------------------------------------------------------------------------------------------------
             Power conductor                 Ampacity *                 Outside diameter **  (inches)
----------------------------------------------------------------------------------------------------------------
                                             Amperes per     SHD-GC 2001 to    SHD-CGC 2001 to   SHD-PCG 2001 to
            Size AWG or kcmil                 conductor        5000 volts        5000 volts        5000 volts
----------------------------------------------------------------------------------------------------------------
6.......................................                93              1.56              1.62  ................
4.......................................               122              1.68              1.73  ................
3.......................................               140              1.78              1.82              1.94
2.......................................               159              1.87              1.91              2.03
1.......................................               184              1.95              1.98              2.12
1/0.....................................               211              2.08              2.10              2.26
2/0.....................................               243              2.20              2.20              2.40
3/0.....................................               279              2.36              2.36              2.58
4/0.....................................               321              2.50              2.50              2.76
250.....................................               355              2.69              2.69  ................
300.....................................               398              2.81              2.81  ................
350.....................................               435              2.95              2.95  ................
500.....................................               536              3.31              3.31  ................
----------------------------------------------------------------------------------------------------------------
 These ampacities are based on single isolated conductor in air, operated with open-circuited shield for a 90
  [deg]C conductor temperature and an ambient temperature of 40 [deg]C.
** Tolerances for the outside diameter are +8%/-5%.

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

0
4. The authority citation for Part 75 continues to read as follows:

    Authority:  30 U.S.C. 811.

0
5. Add Sec. Sec.  75.823 through 75.834 to subpart I, to read as 
follows:


Sec.  75.823  Scope.

    Sections 75.823 through 75.834 of this part are electrical safety 
standards applicable to 2,400 volt continuous mining machines and 
circuits. A ``qualified person'' as used in these sections means a 
person meeting the requirements of Sec.  75.153. Other standards in 30 
CFR apply to these circuits and equipment where appropriate.


Sec.  75.824  Electrical protection.

    (a) Trailing cable protection. The trailing cable extending to the 
high-voltage continuous mining machine must be protected by a circuit-
interrupting device of adequate interrupting capacity and voltage that 
provides short-circuit, overload, ground-fault, and under-voltage 
protection as follows:
    (1) Short-circuit protection.
    (i) The current setting of the device must be the setting specified 
in the approval documentation or 75 percent of the minimum available 
phase-to-phase short-circuit current, whichever is less; and
    (ii) The time-delay setting must not exceed 0.050 seconds.
    (2) Ground-fault protection.
    (i) Neutral grounding resistors must limit the ground-fault current 
to no more than 0.5 ampere.
    (ii) Ground-fault devices must cause de-energization of the circuit 
extending to the continuous mining machine at not more than 0.125 
ampere. The time-delay of the device must not exceed 0.050 seconds.
    (iii) Look-ahead circuits must detect a ground-fault condition and 
prevent the circuit-interrupting device from closing as long as the 
ground-fault condition exists.
    (iv) Backup ground-fault devices must cause de-energization of the 
circuit extending to the continuous mining machine at not more than 40 
percent of the voltage developed across the neutral grounding resistor 
when a ground fault occurs with the neutral grounding resistor open. 
The time-delay setting of the backup device must not exceed 0.25 
seconds.
    (v) Thermal devices must detect a sustained ground-fault current in 
the neutral grounding resistor and must de-energize the incoming power. 
The device must operate at either 50 percent of the maximum temperature 
rise of the neutral grounding resistor or 302[deg] F (150[deg] C), 
whichever is less. Thermal protection must not be dependent on control 
power and may consist of a current transformer and over-current

[[Page 17550]]

relay in the neutral grounding resistor circuit.
    (vi) A single window-type current transformer that encircles all 
three-phase conductors must be used to activate the ground-fault device 
protecting the continuous mining machine. Equipment grounding 
conductors must not pass through the current transformer.
    (vii) A test circuit for the ground-fault device must be provided. 
The test circuit must inject no more than 50 percent of the current 
rating of the neutral grounding resistor through the current 
transformer. When the test circuit is activated, the circuit-
interrupting device must open.
    (3) Under-voltage protection. The under-voltage device must operate 
on a loss of voltage, de-energize the circuit, and prevent the 
equipment from automatically restarting.
    (b) Re-closing. Circuit-interrupting devices must not re-close 
automatically.
    (c) Onboard Power Circuits. When a grounded-phase indicator light 
circuit is used and it indicates a grounded-phase fault, the following 
corrective actions must be taken:
    (1) The machine must be moved immediately to a location with a 
properly supported roof; and
    (2) The grounded-phase condition must be located and corrected 
prior to placing the continuous mining machine back into operation.


Sec.  75.825  Power centers.

    (a) Main disconnecting switch. The power center supplying high 
voltage power to the continuous mining machine must be equipped with a 
main disconnecting switch that, when in the open position, de-energizes 
input to all power transformers.
    (b) Trailing cable disconnecting device. In addition to the main 
disconnecting switch required in paragraph (a) of this section, the 
power center must be equipped with a disconnecting device for each 
circuit that supplies power to a high-voltage continuous mining 
machine. A disconnecting device is defined as a disconnecting switch or 
a cable coupler.
    (c) Disconnecting switches. Each disconnecting switch must be 
labeled to clearly identify the circuit it disconnects, and be designed 
and installed as follows:
    (1) Rated for the maximum phase-to-phase voltage of the circuit;
    (2) Rated for the full-load current of the circuit that is supplied 
power through the device.
    (3) Allow for visual observation, without removing any covers, to 
verify that the contacts are open;
    (4) Ground all power conductors on the load side when the switch is 
in the ``open and grounded'' position;
    (5) Can only be locked out in the ``open and grounded'' position; 
and
    (6) Safely interrupts the full-load current of the circuit or 
causes the current to be interrupted automatically before the 
disconnecting switch opens.
    (d) Barriers and covers. All compartments that provide access to 
high-voltage circuits must have barriers and/or covers to prevent 
miners from contacting energized high-voltage circuits.
    (e) Main disconnecting switch and control circuit interlocking. The 
control circuit must be interlocked with the main disconnecting switch 
in the power center so that:
    (1) When the main disconnecting switch is in the ``open'' position, 
the control circuit can only be powered through an auxiliary switch in 
the ``test'' position; and
    (2) When the main disconnecting switch is in the ``closed'' 
position, the control circuit can only be powered through an auxiliary 
switch in the ``normal'' position.
    (f) Interlocks. Each cover or removable barrier providing access to 
high-voltage circuits must be equipped with at least two interlock 
switches. Except when the auxiliary switch is on the ``test'' position, 
removal of any cover or barrier that exposes energized high-voltage 
circuits must cause the interlock switches to automatically de-energize 
the incoming circuit to the power center.
    (g) Emergency stop switch. The power center must be equipped with 
an externally accessible emergency stop switch hard-wired into the 
incoming ground-wire monitor circuit that de-energizes the incoming 
high-voltage in the event of an emergency.
    (h) Grounding stick. The power center must be equipped with a 
grounding stick to be used prior to performing electrical work to 
assure that high-voltage capacitors are discharged and circuits are de-
energized. The power center must have a label readily identifying the 
location of the grounding stick. The grounding stick must be stored in 
a dry location.
    (i) Caution label. All compartments providing access to energized 
high-voltage conductors and parts must display a caution label to warn 
miners against entering the compartments before de-energizing incoming 
high-voltage circuits.


Sec.  75.826  High-voltage trailing cables.

    High-voltage trailing cables must:
    (a) Meet existing trailing cable requirements and the approval 
requirements of the high-voltage continuous mining machine; and
    (b) Meet existing ground-check conductor requirements (Sec.  
75.804) or have a stranded center ground-check conductor not smaller 
than a No. 16 A.W.G.


Sec.  75.827  Guarding of trailing cables.

    (a) Guarding.
    (1) The high-voltage cable must be guarded in the following 
locations:
    (i) From the power center cable coupler for a distance of 10 feet 
inby the power center;
    (ii) From the entrance gland for a distance of 10 feet outby the 
last strain clamp on the continuous mining machine; and,
    (iii) At any location where the cable could be damaged by moving 
equipment.
    (2) Guarding must be constructed using nonconductive flame-
resistant material or grounded metal.
    (b) Suspended cables and cable crossovers. When equipment must 
cross any portion of the cable, the cable must be either:
    (1) Suspended from the mine roof; or
    (2) Protected by a cable crossover having the following 
specifications:
    (i) A minimum length of 33 inches;
    (ii) A minimum width of 17 inches;
    (iii) A minimum height of 3 inches;
    (iv) A minimum cable placement area of two and one half-inches 
(2\1/2\) high by four and one-quarter inches (4\1/
4\) wide;
    (v) Made of nonconductive material;
    (vi) Made of material with a distinctive color. The color black 
must not be used; and
    (vii) Made of material that has a minimum compressive strength of 
6,400 pounds per square inch (psi).


Sec.  75.828  Trailing cable pulling.

    The trailing cable must be de-energized prior to being pulled by 
any equipment other than the continuous mining machine. The cable 
manufacturer's recommended pulling procedures must be followed when 
pulling the trailing cable with equipment other than the continuous 
mining machine.


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

    (a) Conditions of use. Tramming the continuous mining machine in 
and out of the mine and from section to section must be done in 
accordance with movement requirements of high-voltage power centers and 
portable transformers (Sec.  75.812) and as follows:
    (1) The power source must not be located in areas where permissible 
equipment is required;

[[Page 17551]]

    (2) The continuous mining machine must not be used for mining or 
cutting purposes, unless a power center is used in accordance with 
Sec. Sec.  75.823 through 75.828 and Sec. Sec.  75.830 through 75.833;
    (3) Low-, medium-, and high-voltage cables must comply with 
Sec. Sec.  75.600-1, 75.907, and 75.826, as applicable; and
    (4) The energized high-voltage cable must be mechanically secured 
onboard the continuous mining machine. This provision applies only when 
using the power sources specified in paragraphs (c)(2) and (c)(3) of 
this section.
    (b) Testing prior to tramming. Prior to tramming the continuous 
mining machine,
    (1) A qualified person must activate the ground-fault and ground-
wire monitor test circuits of the power sources specified in paragraph 
(c) of this section to assure that the corresponding circuit-
interrupting device opens the circuit. Corrective actions and 
recordkeeping resulting from these tests must be in accordance with 
Sec. Sec.  75.832(f) and (g).
    (2) Where applicable, a person designated by the mine operator must 
activate the test circuit for the grounded-phase detection circuit on 
the continuous mining machine to assure that the detection circuit is 
functioning properly. Corrective actions resulting from this test must 
be in accordance with Sec.  75.832(f).
    (c) Power sources. In addition to the power center specified in 
Sec.  75.825, the following power sources may be used to tram the 
continuous mining machine.
    (1) Medium-voltage power source. A medium-voltage power source is a 
source that supplies 995 volts through a trailing cable (See Figure 1 
of this section) to the continuous mining machine. The medium-voltage 
power source must--
    (i) Not be used to back-feed the high-voltage circuits of the 
continuous mining machine; and
    (ii) Meet all applicable requirements for medium-voltage circuits 
in 30 CFR 75.
[GRAPHIC] [TIFF OMITTED] TR06AP10.002

    (2) Step-up transformer. A step-up transformer is a transformer 
that steps up the low or medium voltage to high voltage (See Figure 2 
in this section) and must meet the following requirements:
    (i) The trailing cable supplying low or medium voltage to the step-
up transformer must meet the applicable requirements of 30 CFR part 75;
    (ii) The high-voltage circuit output of the step-up transformer 
supplying power to the continuous mining machine must meet the 
applicable provisions of Sec.  75.824;
    (iii) The step-up transformer enclosure must be--
    (A) Securely mounted to minimize vibration on:
    (1) The continuous mining machine; or
    (2) A sled/cart that must be connected to the continuous mining 
machine by a tow-bar and be in close proximity to the mining machine.
    (B) Grounded as follows:
    (1) Connected to the incoming ground conductor of the low- or 
medium-voltage trailing cable;
    (2) Bonded by a No. 1/0 A.W.G. or larger external grounding 
conductor to the continuous mining machine frame; and
    (3) Bonded by a No. 1/0 A.W.G. or larger external grounding 
conductor to the metallic shell of each cable coupler.
    (C) Equipped with:
    (1) At least two interlock switches for each of the enclosure 
covers; and
    (2) An external emergency stop switch to remove input power to the 
step-up transformer.
[GRAPHIC] [TIFF OMITTED] TR06AP10.003

Sec.  75.830  Splicing and repair of trailing cables.

    (a) Splices and repairs.
    (1) Splicing means the mechanical joining of one or more severed 
conductors in a single length of a cable including the replacement of: 
Insulation, semi-conductive tape, metallic shielding, and the outer 
jacket(s).
    (2) Repair means to fix damage to any component of the cable other 
than the conductor.
    (3) Splices and repairs to high-voltage trailing cables must be 
made:
    (i) Only by a qualified person trained in the proper methods of 
splicing and repairing high-voltage trailing cables;
    (ii) In a workman-like manner;
    (iii) In accordance with Sec.  75.810; and
    (iv) Using only MSHA-approved high-voltage kits that include 
instructions for outer-jacket repairs and splices.

[[Page 17552]]

    (b) Splicing limitations.
    (1) Splicing of the high-voltage trailing cable within 35 feet of 
the continuous mining machine is prohibited.
    (2) Only four (4) splices will be allowed at any one time for the 
portion of the trailing cable that extends from the continuous miner 
outby for a distance of 300 feet.


Sec.  75.831  Electrical work; troubleshooting and testing.

    (a) Trailing cable and continuous mining machine electrical work 
procedures. Prior to performing electrical work, other than 
troubleshooting and testing, on the high-voltage trailing cable or the 
continuous mining machine, a qualified person must de-energize the 
power center and follow procedures specified in paragraph (1) or (2):
    (1) If a trailing cable disconnecting switch is provided:
    (i) Open and ground the power conductors, lock out and tag the 
disconnecting switch; and
    (ii) Lock out and tag the plug to the power receptacle.
    (2) If a trailing cable disconnecting switch is not provided and a 
cable coupler is used as a disconnecting device:
    (i) Remove the plug from the power receptacle and connect it to the 
grounding receptacle;
    (ii) Lock out and tag the plug to the grounding receptacle; and
    (iii) Place a dust cover over the power receptacle.
    (b) Troubleshooting and testing the trailing cable. During 
troubleshooting and testing, the de-energized high-voltage cable may be 
disconnected from the power center only for that period of time 
necessary to locate the defective condition. Prior to troubleshooting 
and testing trailing cables, a qualified person must perform the 
following:
    (1) If a trailing cable disconnecting switch is provided:
    (i) Open and ground power conductors and lock out and tag the 
disconnecting switch;
    (ii) Disconnect the plug from the power receptacle;
    (iii) Lock out and tag the plug; and
    (iv) Place a dust cover over the power receptacle.
    (2) If a trailing cable disconnecting switch is not provided and a 
cable coupler is used as a disconnecting device:
    (i) Remove the plug from the power receptacle and connect it to the 
grounding receptacle to ground the power conductors;
    (ii) Remove the plug from the grounding receptacle and install a 
lock and tag on the plug; and
    (iii) Place a dust cover over the power receptacle.
    (c) Troubleshooting and testing limitations. Troubleshooting and 
testing energized circuits must be performed only:
    (1) On low- and medium-voltage circuits;
    (2) When the purpose of troubleshooting and testing is to determine 
voltages and currents;
    (3) By qualified persons; and
    (4) When using protective gloves in accordance with the following 
table:

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

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


Sec.  75.832  Frequency of examinations; recordkeeping.

    (a) Continuous mining machine examination. At least once every 7 
days, a qualified person must examine each high-voltage continuous 
mining machine to verify that electrical protection, equipment 
grounding, permissibility, cable insulation, and control devices are 
properly installed and maintained.
    (b) Ground-fault test circuit. At least once every 7 days, and 
prior to tramming the high-voltage continuous mining machine, a 
qualified person must activate the ground-fault test circuit to verify 
that it will cause the corresponding circuit-interrupting device to 
open.
    (c) Ground-wire monitor test. At least once every 7 days, and prior 
to tramming the high-voltage continuous mining machine, a qualified 
person must examine and test each high-voltage continuous mining 
machine ground-wire monitor circuit to verify that it will cause the 
corresponding circuit-interrupting device to open.
    (d) Trailing cable inspections.
    (1) Once each day during the shift that the continuous mining 
machine is first energized, a qualified person must de-energize and 
inspect the entire length of the high-voltage trailing cable from the 
power center to the continuous mining machine. The inspection must 
include examination of the outer jacket repairs and splices for damage, 
and assure guarding is provided where required.
    (2) At the beginning of each shift that the continuous mining 
machine is energized, a person designated by the mine operator must de-
energize and visually inspect the high-voltage trailing cable for 
damage to the outer jacket. This inspection must be conducted from the 
continuous mining machine to the following locations:
    (i) The last open crosscut;
    (ii) Within 150 feet of the working place during retreat or second 
mining; or
    (iii) Up to 150 feet from the continuous mining machine when the 
machine is used in outby areas.

[[Page 17553]]

    (e) Grounded-phase detection test. When a grounded-phase test 
circuit is provided on a high-voltage continuous mining machine, a 
person designated by the mine operator must activate the test circuit 
at the beginning of each production shift to assure that the detection 
circuit is functioning properly.
    (f) Corrective action. When examinations or tests of equipment 
reveal a risk of fire, electrical shock, ignition, or operational 
hazard, the equipment must be immediately removed from service or 
repaired.
    (g) Record of tests.
    (1) At the completion of examinations and tests required under 
paragraphs (a), (b), and (c) of this section, the person conducting the 
examinations and tests must:
    (i) Certify by signature and date that the examinations and tests 
have been conducted.
    (ii) Make a record of any unsafe condition found.
    (2) Any corrective action(s) must be recorded by the person taking 
the corrective action.
    (3) The record must be countersigned by the mine foreman or 
equivalent mine official by the end of the mine foreman's or the 
equivalent mine official's next regularly scheduled working shift.
    (4) Records must be maintained in a secure book that is not 
susceptible to alteration or electronically in a computer system so as 
to be secure and not susceptible to alteration.
    (5) Certifications and records must be kept for at least 1 year and 
must be made available for inspection by authorized representatives of 
the Secretary and representatives of miners.


Sec.  75.833  Handling high-voltage trailing cables.

    (a) Cable handling.
    (1) Miners must not handle energized trailing cables unless they 
are wearing high-voltage insulating gloves, which include the rubber 
gloves and leather outer protector gloves, or are using insulated cable 
handling tools that meet the requirements of paragraph (c) or (d) of 
this section.
    (2) Miners must not handle energized high-voltage cables with any 
parts of their bodies except by hand in accordance with paragraph (1) 
above.
    (b) Availability. Each mine operator must make high-voltage 
insulating gloves or insulated cable handling tools available to miners 
handling energized high-voltage trailing cables.
    (c) High-voltage insulating gloves. High-voltage insulating gloves 
must meet the following requirements:
    (1) The rubber gloves must be designed and maintained to have a 
voltage rating of at least Class 1 (7,500 volts) and tested every 30 
days in accordance with publication ASTM F496-02a, ``Standard 
Specification for In-Service Care of Insulating Gloves and Sleeves'' 
(2002). The Director of the Federal Register approved this 
incorporation by reference in accordance with 5 U.S.C. 522(a) and 1 CFR 
part 51. ASTM F496-02a may be obtained from the American Society for 
Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, 
Pennsylvania 19428-2959, call 610-832-9500 or go to http://astm.org. 
ASTM F496-02a is available for inspection at any MSHA Coal Mine Safety 
and Health District office, at the MSHA Office of Standards, 
Regulations, and Variances, 1100 Wilson Boulevard, Room 2350, 
Arlington, VA 22209-3939, 202-693-9440, or at the National Archives and 
Records Administration (NARA). For information on the availability of 
this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
    (2) The rubber glove portion must be air-tested at the beginning of 
each shift to assure its effectiveness.
    (3) Both the leather protector and rubber insulating gloves must be 
visually examined before each use for signs of damage or defects.
    (4) Damaged rubber gloves must be removed from the underground area 
of the mine or destroyed. Leather protectors must be maintained in good 
condition or replaced.
    (d) Insulated cable handling tools. Insulated cable handling tools 
must be:
    (1) Rated and properly maintained to withstand at least 7,500 
volts;
    (2) Designed and manufactured for cable handling;
    (3) Visually examined before each use for signs of damage or 
defects; and
    (4) Removed from the underground area of the mine or destroyed if 
damaged or defective.


Sec.  75.834  Training.

    In addition to existing part 48 task training, hazard training, 
training for qualified persons under existing Sec.  75.153, and annual 
refresher training, the following specialized training shall be 
provided and specified in the part 48 plan:
    (a) Training for miners who perform maintenance on high-voltage 
continuous mining machines in high-voltage safety, testing, and repair 
and maintenance procedures.
    (b) Training for personnel who work in the vicinity of high-voltage 
continuous mining machines in safety procedures and precautions for 
moving the high-voltage machines or the trailing cables.

0
6. Amend Sec.  75.1002 by adding paragraph (b)(5) to read as follows:


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

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

[FR Doc. 2010-7309 Filed 4-5-10; 8:45 am]
BILLING CODE 4510-13-P