Title 30—Mineral Resources--Volume 1
PART 75—MANDATORY SAFETY STANDARDS—UNDERGROUND COAL MINES
§ 75.371   Mine ventilation plan; contents.
The mine ventilation plan shall contain the information described below and any additional provisions required by the district manager:
(a) The mine name, company name, mine identification number, and the name of the individual submitting the plan information.
(b) Planned main mine fan stoppages, other than those scheduled for testing, maintenance or adjustment, including procedures to be followed during these stoppages and subsequent restarts (see § 75.311(a)) and the type of device to be used for monitoring main mine fan pressure, if other than a pressure recording device (see 75.310(a)(4)).
(c) Methods of protecting main mine fans and associated components from the forces of an underground explosion if a 15-foot offset from the nearest side of the mine opening is not provided (see § 75.310(a)(6)); and the methods of protecting main mine fans and intake air openings if combustible material will be within 100 feet of the area surrounding the fan or these openings (see § 75.311(f)).
(d) Persons that will be permitted to enter the mine, the work these persons will do while in the mine, and electric power circuits that will be energized when a back-up fan system is used that does not provide the ventilating quantity provided by the main mine fan (see § 75.311(c)).
(e) The locations and operating conditions of booster fans installed in anthracite mines (see § 75.302).
(f) Section and face ventilation systems used and the minimum quantity of air that will be delivered to the working section for each mechanized mining unit, including drawings illustrating how each system is used, and a description of each different dust suppression system used on equipment, identified by make and model, on each working section, including:
(1) The number, types, location, orientation, operating pressure, and flow rate of operating water sprays;
(2) The maximum distance that ventilation control devices will be installed from each working face when mining or installing roof bolts in entries and crosscuts;
(3) Procedures for maintaining the roof bolting machine dust collection system in approved condition; and
(4) Recommended best work practices for equipment operators to minimize dust exposure.
(g) Locations where the air quantities must be greater than 3,000 cubic feet per minute (see § 75.325(a)(1)).
(h) In anthracite mines, locations where the air quantities must be greater than 1,500 cubic feet per minute (see § 75.325(e)(1)).
(i) Working places and working faces other than those where coal is being cut, mined, drilled for blasting or loaded, where a minimum air quantity will be maintained, and the air quantity at those locations (see § 75.325(a)(1)).
(j) The operating volume of machine mounted dust collectors or diffuser fans, if used (see § 75.325(a)(3)), including the type and size of dust collector screen used, and a description of the procedures to maintain dust collectors used on equipment.
(k) The minimum mean entry air velocity in exhausting face ventilation systems where coal is being cut, mined, drilled for blasting, or loaded, if the velocity will be less than 60 feet per minute. Other working places where coal is not being cut, mined, drilled for blasting or loaded, where at least 60 feet per minute or some other minimum mean entry air velocity will be maintained (see § 75.326).
(l) The maximum distance if greater than 10 feet from each working face at which face ventilation control devices will be installed (see § 75.330(b)(2)). The working places other than those where coal is being cut, mined, drilled for blasting or loaded, where face ventilation control devices will be used (see § 75.330(b)(1)(ii).
(m) The volume of air required in the last open crosscut or the quantity of air reaching the pillar line if greater than 9,000 cubic feet per minute (see § 75.325(b)).
(n) In anthracite mines, the volume of air required in the last open crosscut or the quantity of air reaching the pillar line if greater than 5,000 cubic feet per minute (see § 75.325(e)(2)).
(o) Locations where separations of intake and return air courses will be built and maintained to other than the third connecting crosscut outby each working face (see § 75.333(b)(1)).
(p) The volume of air required at the intake to the longwall sections, if different than 30,000 cubic feet per minute (see § 75.325(c)).
(q) The velocities of air on a longwall or shortwall face, and the locations where the velocities must be measured (see § 75.325(c)(2)).
(r) The minimum quantity of air that will be provided during the installation and removal of mechanized mining equipment, the location where this quantity will be provided, and the ventilation controls that will be used (see § 75.325(d), (g), and (i)).
(s) The locations and frequency of the methane tests if required more often by § 75.362(d)(1)(iii) (see § 75.362 (d)(1)(iii).
(t) The locations where samples for “designated areas” will be collected, including the specific location of each sampling device, and the respirable dust control measures used at the dust generating sources for these locations (see §§ 70.207 and 70.209 of this chapter).
(u) The methane and dust control systems at underground dumps, crushers, transfer points, and haulageways.
(v) Areas in trolley haulage entries where the air velocity will be greater than 250 feet per minute and the velocity in these areas (see § 75.327(b)).
(w) Locations where entries will be advanced less than 20 feet from the inby rib without a crosscut being provided where a line brattice will be required. (see § 75.333(g)).
(x) A description of the bleeder system to be used, including its design (see § 75.334).
(y) The means for determining the effectiveness of bleeder systems (see § 75.334(c)(2)).
(z) The locations where measurements of methane and oxygen concentrations and air quantities and tests to determine whether the air is moving in the proper direction will be made to evaluate the ventilation of nonpillared worked-out areas (see § 75.364 (a)(1)) and the effectiveness of bleeder systems (see § 75.364 (a)(2)(iii). Alternative methods of evaluation of the effectiveness of bleeder systems (§ 75.364 (a)(2)(iv)).
(aa) The means for adequately maintaining bleeder entries free of obstructions such as roof falls and standing water (see § 75.334(c)(3)).
(bb) The location of ventilation devices such as regulators, stoppings and bleeder connectors used to control air movement through worked-out areas (see § 75.334(c)(4)). The location and sequence of construction of proposed seals for each worked-out area. (see § 75.334(e)).
(cc) In mines with a demonstrated history of spontaneous combustion: a description of the measures that will be used to detect methane, carbon monoxide, and oxygen concentration during and after pillar recovery and in worked-out areas where no pillars have been recovered (see § 75.334(f)(1); and, the actions which will be taken to protect miners from the hazards associated with spontaneous combustion (see § 75.334(f)(2). If a bleeder system will not be used, the methods that will be used to control spontaneous combustion, accumulations of methane-air mixtures, and other gases, dusts, and fumes in the worked-out area (see § 75.334(f)(3)).
(dd) The location of all horizontal degasification holes that are longer than 1,000 feet and the location of all vertical degasification holes.
(ee) If methane drainage systems are used, a detailed sketch of each system, including a description of safety precautions used with the systems.
(ff) Seal installation requirements provided by § 75.335 and the sampling provisions provided by § 75.336.
(gg) The alternative location for the additional sensing device if the device will not be installed on the longwall shearing machine (see § 75.342(a)(2)).
(hh) The ambient level in parts per million of carbon monoxide, and the method for determining the ambient level, in all areas where carbon monoxide sensors are installed.
(ii) The locations (designated areas) where dust measurements would be made in the belt entry when belt air is used to ventilate working sections or areas where mechanized mining equipment is being installed or removed, in accordance with § 75.350(b)(3).
(jj) The locations and approved velocities at those locations where air velocities in the belt entry are above or below the limits set forth in § 75.350(a)(2) or §§ 75.350(b)(7) and 75.350(b)(8).
(kk) The locations where air quantities are measured as set forth in § 75.350(b)(6).
(ll) The locations and use of point-feed regulators, in accordance with §§ 75.350(c) and 75.350(d)(5).
(mm) The location of any diesel-discriminating sensor, and additional carbon monoxide or smoke sensors installed in the belt air course.
(nn) The length of the time delay or any other method used to reduce the number of non-fire related alert and alarm signals from carbon monoxide sensors.
(oo) The reduced alert and alarm settings for carbon monoxide sensors, in accordance with § 75.351(i)(2).
(pp) The alternate detector and the alert and alarm levels associated with the detector, in accordance with § 75.352(e)(7).
(qq) The distance that separation between the primary escapeway and the belt or track haulage entries will be maintained if other than to the first connecting crosscut outby the section loading point (see § 75.380(g)).
(rr) In anthracite mines, the dimensions of escapeways where the pitch of the coal seam does not permit escapeways to be maintained 4 feet by 5 feet and the locations where these dimensions must be maintained (see § 75.381(c)(4)).
(ss) Areas designated by the district manager where measurements of CO and NO 2 concentrations will be made (see § 70.1900(a)(4)).
(tt) Location where the air quantity will be maintained at the section loading point (see § 75.325(f)(2)).
(uu) Any additional location(s) required by the district manager where a minimum air quantity must be maintained for an individual unit of diesel-powered equipment. (see § 75.325(f)(5)).
(vv) The minimum air quantities that will be provided where multiple units of diesel-powered equipment are operated (see § 75.325(g) (1)-(3) and (i)).
(ww) The diesel-powered mining equipment excluded from the calculation under § 75.325(g). (see § 75.325(h)).
(xx) Action levels higher than the 50 percent level specified by § 70.1900(c). (see § 75.325(j)).
(yy) The locations where the pressure differential cannot be maintained from the primary escapeway to the belt entry.
§ 75.372   Mine ventilation map.
(a)(1) At intervals not exceeding 12 months, the operator shall submit to the district manager 3 copies of an up-to-date map of the mine drawn to a scale of not less than 100 nor more than 500 feet to the inch. A registered engineer or a registered surveyor shall certify that the map is accurate.
(2) In addition to the informational requirements of this section the map may also be used to depict and explain plan contents that are required in § 75.371. Information shown on the map to satisfy the requirements of § 75.371 shall be subject to approval by the district manager.
(b) The map shall contain the following information:
(1) The mine name, company name, mine identification number, a legend identifying the scale of the map and symbols used, and the name of the individual responsible for the information on the map.
(2) All areas of the mine, including sealed and unsealed worked-out areas.
(3) All known mine workings that are located in the same coalbed within 1,000 feet of existing or projected workings. These workings may be shown on a mine map with a scale other than that required by paragraph (a) of this section, if the scale does not exceed 2,000 feet to the inch and is specified on the map.
(4) The locations of all known mine workings underlying and overlying the mine property and the distance between the mine workings.
(5) The locations of all known oil and gas wells and all known drill holes that penetrate the coalbed being mined.
(6) The locations of all main mine fans, installed backup fans and motors, and each fan's specifications, including size, type, model number, manufacturer, operating pressure, motor horsepower, and revolutions per minute.
(7) The locations of all surface mine openings and the direction and quantity of air at each opening.
(8) The elevation at the top and bottom of each shaft and slope, and shaft and slope dimensions, including depth and length.
(9) The direction of air flow in all underground areas of the mine.
(10) The locations of all active working sections and the four-digit identification number for each mechanized mining unit (MMU).
(11) The location of all escapeways and refuge alternatives.
(12) The locations of all ventilation controls, including permanent stoppings, overcasts, undercasts, regulators, seals, airlock doors, haulageway doors and other doors, except temporary ventilation controls on working sections.
(13) The direction and quantity of air—
(i) Entering and leaving each split;
(ii) In the last open crosscut of each set of entries and rooms; and
(iii) At the intake end of each pillar line, including any longwall or shortwall.
(14) Projections for at least 12 months of anticipated mine development, proposed ventilation controls, proposed bleeder systems, and the anticipated location of intake and return air courses, belt entries, and escapeways.
(15) The locations of existing methane drainage systems.
(16) The locations and type of all AMS sensors required by subpart D of this part.
(17) Contour lines that pass through whole number elevations of the coalbed being mined. These lines shall be spaced at 10-foot elevation levels unless a wider spacing is permitted by the district manager.
(18) The location of proposed seals for each worked-out area.
(19) The entry height, velocity and direction of the air current at or near the midpoint of each belt flight where the height and width of the entry are representative of the belt haulage entry.
(20) The location and designation of air courses that have been redesignated from intake to return for the purpose of ventilation of structures, areas or installations that are required by this subpart D to be ventilated to return air courses, and for ventilation of seals.
(c) The mine map required by § 75.1200 may be used to satisfy the requirements for the ventilation map, provided that all the information required by this section is contained on the map.
§ 75.373   Reopening mines.
After a mine is abandoned or declared inactive, and before it is reopened, mining operations shall not begin until MSHA has been notified and has completed an inspection.
§ 75.380   Escapeways; bituminous and lignite mines.
(a) Except in situations addressed in § 75.381, § 75.385 and § 75.386, at least two separate and distinct travelable passageways shall be designated as escapeways and shall meet the requirements of this section.
(b) (1) Escapeways shall be provided from each working section, and each area where mechanized mining equipment is being installed or removed, continuous to the surface escape drift opening or continuous to the escape shaft or slope facilities to the surface.
(2) During equipment installation, these escapeways shall begin at the projected location for the section loading point. During equipment removal, they shall begin at the location of the last loading point.
(c) The two separate and distinct escapeways required by this section shall not end at a common shaft, slope, or drift opening, except that multiple compartment shafts or slopes separated by walls constructed of noncombustible material may be used as separate and distinct passageways.
(d) Each escapeway shall be—
(1) Maintained in a safe condition to always assure passage of anyone, including disabled persons;
(2) Clearly marked to show the route and direction of travel to the surface;
(3) Maintained to at least a height of 5 feet from the mine floor to the mine roof, excluding the thickness of any roof support, except that the escapeways shall be maintained to at least the height of the coalbed, excluding the thickness of any roof support, where the coalbed is less than 5 feet. In areas of mines where escapeways pass through doors, the height may be less than 5 feet, provided that sufficient height is maintained to enable miners, including disabled persons, to escape quickly in an emergency. In areas of mines developed before November 16, 1992, where escapeways pass over or under overcasts or undercasts, the height may be less than 5 feet provided that sufficient height is maintained to enable miners, including disabled persons, to escape quickly in an emergency. When there is a need to determine whether sufficient height is provided, MSHA may require a stretcher test where 4 persons carry a miner through the area in question on a stretcher;
(4) Maintained at least 6 feet wide except—
(i) Where necessary supplemental roof support is installed, the escapeway shall not be less than 4 feet wide; or
(ii) Where the route of travel passes through doors or other permanent ventilation controls, the escapeway shall be at least 4 feet wide to enable miners to escape quickly in an emergency, or
(iii) Where the alternate escapeway passes through doors or other permanent ventilation controls or where supplemental roof support is required and sufficient width is maintained to enable miners, including disabled persons, to escape quickly in an emergency. When there is a need to determine whether sufficient width is provided, MSHA may require a stretcher test where 4 persons carry a miner through the area in question on a stretcher, or
(iv) Where mobile equipment near working sections, and other equipment essential to the ongoing operation of longwall sections, is necessary during normal mining operations, such as material cars containing rock dust or roof control supplies, or is to be used for the evacuation of miners off the section in the event of an emergency. In any instance, escapeways shall be of sufficient width to enable miners, including disabled persons, to escape quickly in an emergency. When there is a need to determine whether sufficient width is provided, MSHA may require a stretcher test where 4 persons carry a miner through the area in question on a stretcher;
(5) Located to follow the most direct, safe and practical route to the nearest mine opening suitable for the safe evacuation of miners; and
(6) Provided with ladders, stairways, ramps, or similar facilities where the escapeways cross over obstructions.
(7) Provided with a continuous, durable directional lifeline or equivalent device that shall be—
(i) Installed and maintained throughout the entire length of each escapeway as defined in paragraph (b)(1) of this section;
(ii) Flame-resistant in accordance with the requirements of part 18 of this chapter upon replacement of existing lifelines; but in no case later than June 15, 2009;
(iii) Marked with a reflective material every 25 feet;
(iv) Located in such a manner for miners to use effectively to escape;
(v) Equipped with one directional indicator cone securely attached to the lifeline, signifying the route of escape, placed at intervals not exceeding 100 feet. Cones shall be installed so that the tapered section points inby;
(vi) Equipped with one sphere securely attached to the lifeline at each intersection where personnel doors are installed in adjacent crosscuts;
(vii) Equipped with two securely attached cones, installed consecutively with the tapered section pointing inby, to signify an attached branch line is immediately ahead.
(A) A branch line leading from the lifeline to an SCSR cache will be marked with four cones with the base sections in contact to form two diamond shapes. The cones must be placed within reach of the lifeline.
(B) A branch line leading from the lifeline to a refuge alternative will be marked with a rigid spiraled coil at least eight inches in length. The spiraled coil must be placed within reach of the lifeline (see Illustration 1 below).
(e) Surface openings shall be adequately protected to prevent surface fires, fumes, smoke, and flood water from entering the mine.
(f) Primary escapeway. (1) One escapeway that is ventilated with intake air shall be designated as the primary escapeway. The primary escapeway shall have a higher ventilation pressure than the belt entry unless the mine operator submits an alternative in the mine ventilation plan to protect the integrity of the primary escapeway, based on mine specific conditions, which is approved by the district manager.
(2) Paragraphs (f)(3) through (f)(7) of this section apply as follows:
(i) To all areas of a primary escapeway developed on or after November 16, 1992;
(ii) Effective as of June 10, 1997, to all areas of a primary escapeway developed between March 30, 1970 and November 16, 1992; and
(iii) Effective as of June 10, 1997, to all areas of the primary escapeway developed prior to March 30, 1970 where separation of the belt and trolley haulage entries from the primary escapeway existed prior to November 16, 1992.
(3) The following equipment is not permitted in the primary escapeway:
(i) Mobile equipment hauling coal except for hauling coal incidental to cleanup or maintenance of the primary escapeway.
(ii) Compressors, except—
(A) Compressors necessary to maintain the escapeway in safe, travelable condition;
(B) Compressors that are components of equipment such as locomotives and rock dusting machines; and
(C) Compressors of less than five horsepower.
(iii) Underground transformer stations, battery charging stations, substations, and rectifiers except—
(A) Where necessary to maintain the escapeway in safe, travelable condition; and
(B) Battery charging stations and rectifiers and power centers with transformers that are either dry-type or contain nonflammable liquid, provided they are located on or near a working section and are moved as the section advances or retreats.
(iv) Water pumps, except—
(A) Water pumps necessary to maintain the escapeway in safe, travelable condition;
(B) Submersible pumps;
(C) Permissible pumps and associated permissible switchgear;
(D) Pumps located on or near a working section that are moved as the section advances or retreats;
(E) Pumps installed in anthracite mines; and
(F) Small portable pumps.
(4) Mobile equipment operated in the primary escapeway, except for continuous miners and as provided in paragraphs (f)(5), (f)(6), and (f)(7) of this section, shall be equipped with a fire suppression system installed according to §§ 75.1107-3 through 75.1107-16 that is—
(i) Manually operated and attended continuously by a person trained in the systems function and use, or
(ii) A multipurpose dry chemical type capable of both automatic and manual activation.
(5) Personnel carriers and small mobile equipment designed and used only for carrying people and small hand tools may be operated in primary escapeways if—
(i) The equipment is provided with a multipurpose dry chemical type fire suppression system capable of both automatic and manual activation, and the suppression system is suitable for the intended application and is listed or approved by a nationally recognized independent testing laboratory, or,
(ii) Battery powered and provided with two 10 pound multipurpose dry chemical portable fire extinguishers.
(6) Notwithstanding the requirements of paragraph (f)(3)(i), mobile equipment not provided with a fire suppression system may operate in the primary escapeway if no one is inby except those persons directly engaged in using or moving the equipment.
(7) Notwithstanding the requirements of paragraph (f)(3)(i), mobile equipment designated and used only as emergency vehicles or ambulances, may be operated in the primary escapeway without fire suppression systems.
(g) Except where separation of belt and trolley haulage entries from designated escapeways did not exist before November 15, 1992, and except as provided in § 75.350(c), the primary escapeway must be separated from belt and trolley haulage entries for its entire length, to and including the first connecting crosscut outby each loading point except when a greater or lesser distance for this separation is specified and approved in the mine ventilation plan and does not pose a hazard to miners.
(h) Alternate escapeway. One escapeway shall be designated as the alternate escapeway. The alternate escapeway shall be separated from the primary escapeway for its entire length, except that the alternate and primary escapeways may be ventilated from a common intake air shaft or slope opening.
(i) Mechanical escape facilities shall be provided and maintained for—
(1) Each shaft that is part of a designated escapeway and is greater than 50 feet in depth; and
(2) Each slope from the coal seam to the surface that is part of a designated escapeway and is inclined more than 9 degrees from the horizontal.
(j) Within 30 minutes after mine personnel on the surface have been notified of an emergency requiring evacuation, mechanical escape facilities provided under paragraph (i) of this section shall be operational at the bottom of shaft and slope openings that are part of escapeways.
(k) Except where automatically activated hoisting equipment is used, the bottom of each shaft or slope opening that is part of a designated escapeway shall be equipped with a means of signaling a surface location where a person is always on duty when anyone is underground. When the signal is activated or the evacuation of persons underground is necessary, the person shall assure that mechanical escape facilities are operational as required by paragraph (j) of this section.
(l)(1) Stairways or mechanical escape facilities shall be installed in shafts that are part of the designated escapeways and that are 50 feet or less in depth, except ladders may be used in shafts that are part of the designated escapeways and that are 5 feet or less in depth.
(2) Stairways shall be constructed of concrete or metal, set on an angle not to exceed 45 degrees from the horizontal, and equipped on the open side with handrails. In addition, landing platforms that are at least 2 feet by 4 feet shall be installed at intervals not to exceed 20 vertical feet on the stairways and equipped on the open side with handrails.
(3) Ladders shall be constructed of metal, anchored securely, and set on an angle not to exceed 60 degrees from the horizontal.
(m) A travelway designed to prevent slippage shall be provided in slope and drift openings that are part of designated escapeways, unless mechanical escape facilities are installed.
§ 75.381   Escapeways; anthracite mines.
(a) Except as provided in §§ 75.385 and 75.386, at least two separate and distinct travelable passageways shall be designated as escapeways and shall meet the requirements of this section.
(b) Escapeways shall be provided from each working section continuous to the surface.
(c) Each escapeway shall be—
(1) Maintained in a safe condition to always assure passage of anyone, including disabled persons;
(2) Clearly marked to show the route of travel to the surface;
(3) Provided with ladders, stairways, ramps, or similar facilities where the escapeways cross over obstructions; and
(4) Maintained at least 4 feet wide by 5 feet high. If the pitch or thickness of the coal seam does not permit these dimensions to be maintained other dimensions may be approved in the ventilation plan.
(5) Provided with a continuous, durable directional lifeline or equivalent device that shall be—
(i) Installed and maintained throughout the entire length of each escapeway as defined in paragraph (b) of this section;
(ii) Flame-resistant in accordance with the requirements of part 18 of this chapter upon replacement of existing lifelines; but in no case later than June 15, 2009;
(iii) Marked with a reflective material every 25 feet;
(iv) Located in such a manner for miners to use effectively to escape;
(v) Equipped with one directional indicator cone securely attached to the lifeline, signifying the route of escape, placed at intervals not exceeding 100 feet. Cones shall be installed so that the tapered section points inby;
(vi) Equipped with one sphere securely attached to the lifeline at each intersection where personnel doors are installed in adjacent crosscuts;
(vii) Equipped with two securely attached cones, installed consecutively with the tapered section pointing inby, to signify an attached branch line is immediately ahead.
(A) A branch line leading from the lifeline to an SCSR cache will be marked with four cones with the base sections in contact to form two diamond shapes. The cones must be placed within reach of the lifeline.
(B) A branch line leading from the lifeline to a refuge alternative will be marked with a rigid spiraled coil at least eight inches in length. The spiraled coil must be placed within reach of the lifeline.
(d) Surface openings shall be adequately protected to prevent surface fires, fumes, smoke, and flood water from entering the mine.
(e) Primary escapeway. One escapeway that shall be ventilated with intake air shall be designated as the primary escapeway. The primary escapeway shall have a higher ventilation pressure than the belt entry unless the mine operator submits an alternative in the mine ventilation plan to protect the integrity of the primary escapeway, based on mine specific conditions, which is approved by the district manager.
(f) Alternate escapeway. One escapeway that shall be designated as the alternate escapeway shall be separated from the primary escapeway for its entire length.
(g) Mechanical escape facilities shall be provided—
(1) For each shaft or slope opening that is part of a primary escapeway; and
(2) For slopes that are part of escapeways, unless ladders are installed.
(h) Within 30 minutes after mine personnel on the surface have been notified of an emergency requiring evacuation, mechanical escape facilities shall be operational at the bottom of each shaft and slope opening that is part of an escapeway.
(i) Except where automatically activated hoisting equipment is used, the bottom of each shaft or slope opening that is part of a primary escapeway shall be equipped with a means of signaling a surface location where a person is always on duty when anyone is underground. When the signal is activated or the evacuation of personnel is necessary, the person on duty shall assure that mechanical escape facilities are operational as required by paragraph (h) of this section.
§ 75.382   Mechanical escape facilities.
(a) Mechanical escape facilities shall be provided with overspeed, overwind, and automatic stop controls.
(b) Every mechanical escape facility with a platform, cage, or other device shall be equipped with brakes that can stop the fully loaded platform, cage, or other device.
(c) Mechanical escape facilities, including automatic elevators, shall be examined weekly. The weekly examination of this equipment may be conducted at the same time as a daily examination required by § 75.1400-3.
(1) The weekly examination shall include an examination of the headgear, connections, links and chains, overspeed and overwind controls, automatic stop controls, and other facilities.
(2) At least once each week, the hoist shall be run through one complete cycle of operation to determine that it is operating properly.
(d) A person trained to operate the mechanical escape facility always shall be available while anyone is underground to provide the mechanical escape facilities, if required, to the bottom of each shaft and slope opening that is part of an escapeway within 30 minutes after personnel on the surface have been notified of an emergency requiring evacuation. However, no operator is required for automatically operated cages, platforms, or elevators.
(e) Mechanical escape facilities shall have rated capacities consistent with the loads handled.
(f) Manually-operated mechanical escape facilities shall be equipped with indicators that accurately and reliably show the position of the facility.
(g) Certification. The person making the examination as required by paragraph (c) of this section shall certify by initials, date, and the time that the examination was made. Certifications shall be made at or near the facility examined.
§ 75.384   Longwall and shortwall travelways.
(a) If longwall or shortwall mining systems are used and the two designated escapeways required by § 75.380 are located on the headgate side of the longwall or shortwall, a travelway shall be provided on the tailgate side of that longwall or shortwall. The travelway shall be located to follow the most direct and safe practical route to a designated escapeway.
(b) The route of travel shall be clearly marked.
(c) When a roof fall or other blockage occurs that prevents travel in the travelway—
(1) Work shall cease on the longwall or shortwall face;
(2) Miners shall be withdrawn from face areas to a safe area outby the section loading point; and
(3) MSHA shall be notified.
(d) Work may resume on the longwall or shortwall face after the procedures set out in §§ 75.215 and 75.222 are implemented.
§ 75.385   Opening new mines.
When new mines are opened, no more than 20 miners at a time shall be allowed in any mine until a connection has been made between the mine openings, and these connections shall be made as soon as possible.
§ 75.386   Final mining of pillars.
When only one mine opening is available due to final mining of pillars, no more than 20 miners at a time shall be allowed in the mine, and the distance between the mine opening and working face shall not exceed 500 feet.
§ 75.388   Boreholes in advance of mining.
(a) Boreholes shall be drilled in each advancing working place when the working place approaches—
(1) To within 50 feet of any area located in the mine as shown by surveys that are certified by a registered engineer or registered surveyor unless the area has been preshift examined;
(2) To within 200 feet of any area located in the mine not shown by surveys that are certified by a registered engineer or registered surveyor unless the area has been preshift examined; or
(3) To within 200 feet of any mine workings of an adjacent mine located in the same coalbed unless the mine workings have been preshift examined.
(b) Boreholes shall be drilled as follows:
(1) Into the working face, parallel to the rib, and within 3 feet of each rib.
(2) Into the working face, parallel to the rib, and at intervals across the face not to exceed 8 feet.
(3) At least 20 feet in depth in advance of the working face, and always maintained to a distance of 10 feet in advance of the working face.
(c) Boreholes shall be drilled in both ribs of advancing working places described in paragraph (a) of this section unless an alternative drilling plan is approved by the District Manager in accordance with paragraph (g) of this section. These boreholes shall be drilled—
(1) At an angle of 45 degrees to the direction of advance;
(2) At least 20 feet in depth; and
(3) At intervals not to exceed 8 feet.
(d) When a borehole penetrates an area that cannot be examined, and before mining continues, a certified person shall, if possible, determine—
(1) The direction of airflow in the borehole;
(2) The pressure differential between the penetrated area and the mine workings;
(3) The concentrations of methane, oxygen, carbon monoxide, and carbon dioxide; and
(4) Whether water is impounded within the penetrated area.
(e) Unless action is taken to dewater or to ventilate penetrated areas, boreholes shall be plugged with wooden plugs or similar devices when—
(1) Tests conducted at the boreholes show that the atmosphere in the penetrated area contains more than 1.0 percent methane, less than 19.5 percent oxygen, or harmful concentrations of carbon monoxide, carbon dioxide or other explosive, harmful or noxious gases;
(2) Tests for methane, oxygen, carbon monoxide, and carbon dioxide cannot be made because air from mine workings is flowing into the penetrated area; or
(3) Water is discharging through the boreholes from the penetrated area into the mine workings.
(f) If mining is to be conducted within 50 feet above or below an inaccessible area of another mine, boreholes shall be drilled, as necessary, according to a plan approved by the district manager.
(g) Alternative borehole patterns that provide the same protection to miners as the pattern established by paragraphs (b) and (c) of this section may be used under a plan approved by the district manager.
§ 75.389   Mining into inaccessible areas.
(a) (1) The operator shall develop and follow a plan for mining into areas penetrated by boreholes drilled under § 75.388.
(2) Mining shall not resume into any area penetrated by boreholes until conditions in the penetrated area can be determined under § 75.388 and the plan for mining-through into the area has been approved by the district manager.
(3) A copy of the procedures to be followed shall be posted near the site of the mining-through operations and the operator shall explain these procedures to all miners involved in the operations.
(b) The procedures specified in the plan shall include—
(1) The method of ventilation, ventilation controls, and the air quantities and velocities in the affected working section and working place;
(2) Dewatering procedures to be used if a penetrated area contains a water accumulation; and
(3) The procedures and precautions to be followed during mining-through operations.
(c) Except for routine mining-through operations that are part of a retreat section ventilation system approved in accordance with § 75.371(f) and (x), the following provisions shall apply:
(1) Before and during mining-through operations, a certified person shall perform air quality tests at intervals and at locations necessary to protect the safety of the miners.
(2) During mining-through operations, only persons involved in these operations shall be permitted in the mine; and
(3) After mining-through, a certified person shall determine that the affected areas are safe before any persons enter the underground areas of the mine.
§ 75.400   Accumulation of combustible materials.
Coal dust, including float coal dust deposited on rock-dusted surfaces, loose coal, and other combustible materials, shall be cleaned up and not be permitted to accumulate in active workings, or on diesel-powered and electric equipment therein.
§ 75.400-1   Definitions.
(a) The term coal dust means particles of coal that can pass a No. 20 sieve.
(b) The term float coal dust means the coal dust consisting of particles of coal that can pass a No. 200 sieve.
(c) The term loose coal means coal fragments larger in size than coal dust.
§ 75.400-2   Cleanup program.
A program for regular cleanup and removal of accumulations of coal and float coal dusts, loose coal, and other combustibles shall be established and maintained. Such program shall be available to the Secretary or authorized representative.
§ 75.401   Abatement of dust; water or water with a wetting agent.
Where underground mining operations in active workings create or raise excessive amounts of dust, water or water with a wetting agent added to it, or other no less effective methods approved by the Secretary or his authorized representative, shall be used to abate such dust. In working places, particularly in distances less than 40 feet from the face, water, with or without a wetting agent, or other no less effective methods approved by the Secretary or his authorized representative, shall be applied to coal dust on the ribs, roof, and floor to reduce dispersibility and to minimize the explosion hazard.
§ 75.401-1   Excessive amounts of dust.
The term “excessive amounts of dust” means coal and float coal dust in the air in such amounts as to create the potential of an explosion hazard.
§ 75.402   Rock dusting.
All underground areas of a coal mine, except those areas in which the dust is too wet or too high in incombustible content to propagate an explosion, shall be rock dusted to within 40 feet of all working faces, unless such areas are inaccessible or unsafe to enter or unless the Secretary or his authorized representative permits an exception upon his finding that such exception will not pose a hazard to the miners. All crosscuts that are less than 40 feet from a working face shall also be rock dusted.
§ 75.402-1   Definition.
The term too wet means that sufficient natural moisture is retained by the dust that when a ball of finely divided material is squeezed in the hands water is exuded.
§ 75.402-2   Exceptions.
Exceptions granted under § 75.402 by the Secretary or his authorized representative shall be reviewed periodically.
§ 75.403   Maintenance of incombustible content of rock dust.
Where rock dust is required to be applied, it shall be distributed upon the top, floor, and sides of all underground areas of a coal mine and maintained in such quantities that the incombustible content of the combined coal dust, rock dust, and other dust shall be not less than 80 percent. Where methane is present in any ventilating current, the percent of incombustible content of such combined dust shall be increased 0.4 percent for each 0.1 percent of methane.
§ 75.403-1   Incombustible content.
Moisture contained in the combined coal dust, rock dust and other dusts shall be considered as a part of the incombustible content of such mixture.
§ 75.404   Exemption of anthracite mines.
Sections 75.401, 75.402, and 75.403 shall not apply to underground anthracite mines.
§ 75.500   Permissible electric equipment.
On and after March 30, 1971:
(a) All junction or distribution boxes used for making multiple power connections inby the last open crosscut shall be permissible;
(b) All handheld electric drills, blower and exhaust fans, electric pumps, and such other low horsepower electric face equipment as the Secretary may designate on or before May 30, 1970, which are taken into or used inby the last open crosscut of any coal mine shall be permissible;
(c) All electric face equipment which is taken into or used inby the last open crosscut of any coal mine classified under any provision of law as gassy prior to March 30, 1970, shall be permissible; and
(d) All other electric face equipment which is taken into or used inby the last crosscut of any coal mine, except a coal mine referred to in § 75.501, which has not been classified under any provision of law as a gassy mine prior to March 30, 1970, shall be permissible.
§ 75.500-1   Other low horsepower electric face equipment.
Other low horsepower electric face equipment designated pursuant to the provisions of § 75.500(b) is all other electric-driven mine equipment, except low horsepower rock dusting equipment, and employs an electric current supplied by either a power conductor or battery and consumes not more than 2,250 watts of electricity and which is taken into or used inby the last open crosscut.
§ 75.501   Permissible electric face equipment; coal seams above water table.
On and after March 30, 1974, all electric face equipment, other than equipment referred to in paragraph (b) of § 75.500, which is taken into and used inby the last open crosscut of any coal mine which is operated entirely in coal seams located above the water table and which has not been classified under any provision of law as a gassy mine prior to March 30, 1970, and in which one or more openings were made prior to December 30, 1969, shall be permissible.
§ 75.501-1   Coal seams above the water table.
As used in § 75.501, the phrase “coal seams above the water table” means coal seams in a mine which are located at an elevation above a river or the tributary of a river into which a local surface water system naturally drains.
§ 75.501-2   Permissible electric face equipment.
(a) On and after March 30, 1971, in mines operated entirely in coal seams which are located at elevations above the water table:
(1) All junction or distribution boxes used for making multiple power connections inby the last open crosscut shall be permissible; and
(2) All handheld electric drills, blower and exhaust fans, electric pumps, and all other electric-driven mine equipment, except low horsepower rock dusting equipment, that employs an electric current supplied by either a power conductor or battery and consumes not more than 2,250 watts of electricity, which is taken into or used inby the last open crosscut shall be permissible.
(b) On and after March 30, 1974, in mines operated entirely in coal seams which are located at elevations above the water table, all electric face equipment which is taken into or used inby the last crosscut shall be permissible.
§ 75.501-3   New openings; mines above water table and never classed gassy.
(a) Where a new opening(s) is proposed to be developed by shaft, slope, or drift from the surface to, or in, any coalbed and the operator considers such proposed new opening(s) to be a part of a mine coming under section 305(a)(2) of the Act and § 75.501 the operator shall so notify the District Manager for the District in which the mine is located in writing prior to the date any actual development (in coal) through such opening(s) is undertaken. Such notification shall include the following information:
(1) Name, address, and identification number of the existing mine.
(2) A current map of the existing mine clearly setting out the proposed new opening(s), mining plan and planned interconnection, if any, with existing workings.
(3) A statement as to when the operator obtained the right to mine the coal which the proposed new opening(s) will traverse.
(4) The name of the coalbeds currently being mined and those which the new opening(s) will traverse.
(5) The expected life of the mine.
(6) The reason(s) for the proposed new opening(s) (for example, haulage, ventilation, drainage, to avoid bad roof, escapeway).
(b) The District Manager shall make a determination based on all of the information submitted by the operator as to whether the proposed new opening(s) will be considered as a part of the existing mine or as a new mine. The following guidelines and criteria shall be used by the District Manager in making his determination:
(1) The effect that the proposed new opening(s) will have on the safety of the men working in the existing mine shall be considered of primary importance.
(2) Whether the operator had a right to mine the coal which the proposed new openings will traverse prior to the date of enactment of the Act (December 30, 1969) and whether the original mining plan included mining such coal.
(3) Whether, in accordance with the usual mining practices common to the particular district, the proposed new openings would have been considered a new mine or part of the existing mine. A number of factors will be considered including, but not limited to:
(i) The relationship between the coalbeds currently being mined, and those proposed to be mined;
(ii) The distance between existing openings and the proposed new opening(s);
(iii) The projected time elapsing between the start of the new opening(s) and planned interconnection, if any, with the existing mine; and
(iv) The projected tonnage of coal which is expected to be mined prior to interconnection where interconnection is planned.
(c) All new opening(s) shall be operated as a new mine prior to receiving a written notification from the District Manager that such new opening(s) will be considered part of an existing mine coming under section 305(a)(2) of the Act and § 75.501.
(d) Nothing in this § 75.501-3 shall be construed to relieve the operator from compliance with any of the mandatory standards contained in this Part 75.
§ 75.502   Permits for noncompliance.
An operator need not comply with paragraph (d) of § 75.500 or with § 75.501 during the period of time specified in a permit issued by the Interim Compliance Panel established by the Act.
§ 75.503   Permissible electric face equipment; maintenance.
The operator of each coal mine shall maintain in permissible condition all electric face equipment required by §§ 75.500, 75.501, 75.504 to be permissible which is taken into or used inby the last open crosscut of any such mine.
§ 75.503-1   Statement listing all electric face equipment.
Each operator of a coal mine shall complete and file Mine Safety and Health Administration Form No. 6-1496 entitled “Coal Operator's Electrical Survey” and Form 6-1496 Supplemental entitled “Operator's Survey of Electrical Face Equipment.” Forms may be obtained from any MSHA Coal Mine Safety and Health district office. Separate forms shall be filed for each mine. Copies one and two of the completed form shall be filed with the Coal Mine District Manager for the district in which each mine is located on or before May 30, 1970. An operator must list all electric face equipment being used at each mine as of the time of filing, all such equipment being repaired, and all standby electric equipment stored at or in the mine which the operator intends to use as face equipment.
§ 75.504   Permissibility of new, replacement, used, reconditioned, additional, and rebuilt electric face equipment.
On and after March 30, 1971, all new, replacement, used, reconditioned, and additional electric face equipment used in any mine referred to in §§ 75.500, 75.501, and 75.503 shall be permissible and shall be maintained in a permissible condition, and in the event of any major overhaul of any item of electric face equipment in use on or after March 30, 1971, such equipment shall be put in, and thereafter maintained in, a permissible condition, unless in the opinion of the Secretary, such equipment or necessary replacement parts are not available.
§ 75.505   Mines classed gassy; use and maintenance of permissible electric face equipment.
Any coal mine which, prior to March 30, 1970, was classed gassy under any provision of law and was required to use permissible electric face equipment and to maintain such equipment in a permissible condition shall continue to use such equipment and to maintain such equipment in such condition.
§ 75.506   Electric face equipment; requirements for permissibility.
(a) Electric-driven mine equipment and accessories manufactured on or after March 30, 1973, will be permissible electric face equipment only (1) if they are fabricated, assembled, or built under an approval, or any extension thereof, issued by the Bureau of Mines or the Mine Safety and Health Administration in accordance with schedule 2G, or any subsequent Bureau of Mines schedule promulgated by the Secretary after March 30, 1970, which amends, modifies, or supersedes the permissibility requirements of schedule 2G, and (2) if they are maintained in a permissible condition.
(b) Except as provided in paragraph (c) of this § 75.506 electric-driven mine equipment and accessories manufactured prior to March 30, 1973, will be permissible electric face equipment (1) if they were fabricated, assembled, or built under an approval, or any extension thereof, issued by the Bureau of Mines in accordance with the schedules set forth below, and (2) if they are maintained in a permissible condition.
(c) Electric driven mine equipment and accessories bearing the Bureau of Mines approval numbers listed in Appendix A to this subpart are permissible electric face equipment only if they are maintained in a permissible condition.
(d) The following equipment will be permissible electric face equipment only if it is approved under the appropriate parts of this chapter, or former Bureau of Mines' approval schedules, and if it is in permissible condition:
(1) Multiple-Shot Blasting Units, part 7 subpart D;
(2) Electric Cap Lamps, part 19;
(3) Electric Mine Lamps Other than Standard Cap Lamps, part 20;
(4) Flame Safety Lamps;
(5) Portable Methane Detectors, part 22;
(6) Telephone and Signaling Devices, part 23;
(7) Single-Shot Blasting Units;
(8) Lighting Equipment for Illuminating Underground Workings;
(9) Methane-Monitoring Systems, part 27; and
(10) Continuous Duty, Warning Light, Portable Methane Detectors, 30 CFR part 29 contained in the 30 CFR, parts 1-199, edition, revised as of July 1, 1999.
§ 75.506-1   Electric face equipment; permissible condition; maintenance requirements.
(a) Except as provided in paragraph (b) of this section, electric face equipment which meets the requirements for permissibility set forth in § 75.506 will be considered to be in permissible condition only if it is maintained so as to meet the requirements for permissibility set forth in the Bureau of Mines schedule under which such electric face equipment was initially approved, or, if the equipment has been modified, it is maintained so as to meet the requirements of the schedule under which such modification was approved.
(b) Electric face equipment bearing the Bureau of Mines approval number listed in Appendix A of this subpart will be considered to be in permissible condition only if it is maintained so as to meet the requirements for permissibility set forth in Bureau of Mines Schedule 2D or, if such equipment has been modified, it is maintained so as to meet the requirements of the schedule under which the modification was approved.
(c) Notwithstanding the provisions of paragraphs (a) and (b) of this section, where the minimum requirements for permissibility set forth in the appropriate Bureau of Mines schedule under which such equipment or modifications were approved have been superseded by the requirements of this Part 75, the latter requirements shall be applicable.
§ 75.507   Power connection points.
Except where permissible power connection units are used, all power-connection points outby the last open crosscut shall be in intake air.
§ 75.507-1   Electric equipment other than power-connection points; outby the last open crosscut; return air; permissibility requirements.
(a) All electric equipment, other than power-connection points, used in return air outby the last open crosscut in any coal mine shall be permissible except as provided in paragraphs (b) and (c) of this section.
(b) Notwithstanding the provisions of paragraph (a) of this section, in any coal mine where nonpermissible electric face equipment may be taken into or used inby the last open crosscut until March 30, 1974, such nonpermissible electric face equipment may be used in return air outby the last open crosscut.
(c) Notwithstanding the provisions of paragraph (a) of this section, in any coal mine where a permit for noncompliance is in effect, nonpermissible electric face equipment specified in such permit for noncompliance may be used in return air outby the last open crosscut for the duration of such permit.
§ 75.508   Map of electrical system.
The location and the electrical rating of all stationary electric apparatus in connection with the mine electric system, including permanent cables, switchgear, rectifying substations, transformers, permanent pumps, and trolley wires and trolley feeder wires, and settings of all direct-current circuit breakers protecting underground trolley circuits, shall be shown on a mine map. Any changes made in a location, electric rating, or setting shall be promptly shown on the map when the change is made. Such map shall be available to an authorized representative of the Secretary and to the miners in such mine.
§ 75.508-1   Mine tracks.
When mine track is used as a conductor of a trolley system, the location of such track shall be shown on the map required by § 75.508, with a notation of the number of rails and the size of such track expressed in pounds per yard.
§ 75.508-2   Changes in electric system map; recording.
Changes made in the location, electrical rating or setting within the mine electrical system shall be recorded on the map of such system no later than the end of the next workday following completion of such changes.
§ 75.509   Electric power circuit and electric equipment; deenergization.
All power circuits and electric equipment shall be deenergized before work is done on such circuits and equipment, except when necessary for trouble shooting or testing.
§ 75.510   Energized trolley wires; repair.
Energized trolley wires may be repaired only by a person trained to perform electrical work and to maintain electrical equipment and the operator of a mine shall require that such person wear approved and tested insulated shoes and wireman's gloves.
§ 75.510-1   Repair of energized trolley wires; training.
The training referred to in § 75.510 must include training in the repair and maintenance of live trolley wires, and in the hazards involved in making such repairs, and in the limitations of protective clothing used to protect against such hazards.
§ 75.511   Low-, medium-, or high-voltage distribution circuits and equipment; repair.
No electrical work shall be performed on low-, medium-, or high-voltage distribution circuits or equipment, except by a qualified person or by a person trained to perform electrical work and to maintain electrical equipment under the direct supervision of a qualified person. Disconnecting devices shall be locked out and suitably tagged by the persons who perform such work, except that in cases where locking out is not possible, such devices shall be opened and suitably tagged by such persons. Locks or tags shall be removed only by the persons who installed them or, if such persons are unavailable, by persons authorized by the operator or his agent.
§ 75.511-1   Qualified person.
To be a qualified person within the meaning of § 75.511, an individual must meet the requirements of § 75.153.
§ 75.512   Electric equipment; examination, testing and maintenance.
All electric equipment shall be frequently examined, tested, and properly maintained by a qualified person to assure safe operating conditions. When a potentially dangerous condition is found on electric equipment, such equipment shall be removed from service until such condition is corrected. A record of such examinations shall be kept and made available to an authorized representative of the Secretary and to the miners in such mine.
§ 75.512-1   Qualified person.
To be a qualified person within the meaning of § 75.512, an individual must meet the requirements of § 75.153.
§ 75.512-2   Frequency of examinations.
The examinations and tests required by § 75.512 shall be made at least weekly. Permissible equipment shall be examined to see that it is in permissible condition.
§ 75.513   Electric conductor; capacity and insulation.
All electric conductors shall be sufficient in size and have adequate current carrying capacity and be of such construction that a rise in temperature resulting from normal operation will not damage the insulating materials.
§ 75.513-1   Electric conductor; size.
An electric conductor is not of sufficient size to have adequate carrying capacity if it is smaller than is provided for in the National Electric Code, 1968. In addition, equipment and trailing cables that are required to be permissible must meet the requirements of the appropriate schedules of the Bureau of Mines.
§ 75.514   Electrical connections or splices; suitability.
All electrical connections or splices in conductors shall be mechanically and electrically efficient, and suitable connectors shall be used. All electrical connections or splices in insulated wire shall be reinsulated at least to the same degree of protection as the remainder of the wire.
§ 75.515   Cable fittings; suitability.
Cables shall enter metal frames of motors, splice boxes, and electric compartments only through proper fittings. When insulated wires other than cables pass through metal frames, the holes shall be substantially bushed with insulated bushings.
§ 75.516   Power wires; support.
All power wires (except trailing cables on mobile equipment, specially designed cables conducting high-voltage power to underground rectifying equipment or transformers, or bare or insulated ground and return wires) shall be supported on well-insulated insulators and shall not contact combustible material, roof, or ribs.
§ 75.516-1   Installed insulators.
Well-insulated insulators is interpreted to mean well-installed insulators. Insulated J-hooks may be used to suspend insulated power cables for temporary installation not exceeding 6 months and for permanent installation of control cables such as may be used along belt conveyors.
§ 75.516-2   Communication wires and cables; installation; insulation; support.
(a) All communication wires shall be supported on insulated hangers or insulated J-hooks.
(b) All communication cables shall be insulated as required by § 75.517-1, and shall either be supported on insulated or uninsulated hangers or J-hooks, or securely attached to messenger wires, or buried, or otherwise protected against mechanical damage in a manner approved by the Secretary or his authorized representative.
(c) All communication wires and cables installed in track entries shall, except when a communication cable is buried in accordance with paragraph (b) of this section, be installed on the side of the entry opposite to trolley wires and trolley feeder wires. Additional insulation shall be provided for communication circuits at points where they pass over or under any power conductor.
(d) For purposes of this section, communication cable means two or more insulated conductors covered by an additional abrasion-resistant covering.
§ 75.517   Power wires and cables; insulation and protection.
Power wires and cables, except trolley wires, trolley feeder wires, and bare signal wires, shall be insulated adequately and fully protected.
§ 75.517-1   Power wires and cables; insulation and protection.
Power wires and cables installed on or after March 30, 1970, shall have insulation with a dielectric strength at least equal to the voltage of the circuit.
§ 75.517-2   Plans for insulation of existing bare power wires and cables.
(a) On or before December 31, 1970, plans for the insulation of existing bare power wires and cables installed prior to March 30, 1970, shall be filed with the District Manager of the Coal Mine Safety District in which the mine is located to permit approval and prompt implementation of such plans.
(b) The appropriate District Manager shall notify the operator in writing of the approval of a proposed insulation plan. If revisions are required for approval, the changes required will be specified.
(c) An insulation plan shall include the following information:
(1) Name and address of the company, the mine and the responsible officials;
(2) Map or diagram indicating location of power wires and cables required to be insulated;
(3) Total length of bare power wires and cables required to be insulated;
(4) Schedule for the replacement or insulation of bare power wires and cables;
(5) Type of insulation to be used and the voltage rating as indicated by the manufacturer.
(d) The District Manager shall be guided by the following criteria in approving insulation plans on a mine-by-mine basis. Insulation not conforming to these criteria may be approved provided the operator can satisfy the Mine Safety and Health Administration that the insulation will provide no less than the same measure of protection.
(1) Insulation shall be adequate for the applied voltage of the circuit.
(2) When tubing is used to insulate existing power wires and cables, it shall have a dielectric strength at least equal to the voltage of the circuit. When the tubing is split for purposes of installation, the joints shall be effectively sealed. The butt ends may be sealed with a moisture resistant insulating tape.
(3) When tape is used to insulate existing power wires and cables, it shall be applied half-lapped and one thickness of the tape shall have a dielectric strength at least equal to the voltage of the circuit. The tape shall be self-adhesive and moisture resistant.
§ 75.518   Electric equipment and circuits; overload and short circuit protection.
Automatic circuit-breaking devices or fuses of the correct type and capacity shall be installed so as to protect all electric equipment and circuits against short circuit and overloads. Three-phase motors on all electric equipment shall be provided with overload protection that will deenergize all three phases in the event that any phase is overloaded.
§ 75.518-1   Electric equipment and circuits; overload and short circuit protection; minimum requirements.
A device to provide either short circuit protection or protection against overload which does not conform to the provisions of the National Electric Code, 1968, does not meet the requirement of § 75.518. In addition, such devices on electric face equipment and trailing cables that are required to be permissible must meet the requirements of the applicable schedules of the Bureau of Mines.
§ 75.518-2   Incandescent lamps, overload and short circuit protection.
Incandescent lamps installed along haulageways and at other locations, not contacting combustible material, and powered from trolley or direct current feeder circuits, need not be provided with separate short circuit or overload protection, if the lamp is not more than 8 feet in distance from such circuits.
§ 75.519   Main power circuits; disconnecting switches.
In all main power circuits, disconnecting switches shall be installed underground within 500 feet of the bottoms of shafts and boreholes through which main power circuits enter the underground area of the mine and within 500 feet of all other places where main power circuits enter the underground area of the mine.
§ 75.519-1   Main power circuits; disconnecting switches; locations.
Section 75.519 requires (a) that a disconnecting switch be installed on the surface at a point within 500 feet of the place where the main power circuit enters the underground area of a mine, and (b) that, in an instance on which a main power circuit enters the underground area through a shaft or borehole, a disconnecting switch be installed underground within 500 feet of the bottom of the shaft or borehole.
§ 75.520   Electric equipment; switches.
All electric equipment shall be provided with switches or other controls that are safely designed, constructed, and installed.
§ 75.521   Lightning arresters; ungrounded and exposed power conductors and telephone wires.
Each ungrounded, exposed power conductor and each ungrounded, exposed telephone wire that leads underground shall be equipped with suitable lightning arresters of approved type within 100 feet of the point where the circuit enters the mine. Lightning arresters shall be connected to a low resistance grounding medium on the surface which shall be separated from neutral grounds by a distance of not less than 25 feet.
§ 75.522   Lighting devices.
No device for the purpose of lighting any coal mine which has not been approved by the Secretary or his authorized representative shall be permitted in such mine.
§ 75.522-1   Incandescent and fluorescent lamps.
(a) Except for areas of a coal mine inby the last open crosscut, incandescent lamps may be used to illuminate underground areas. When incandescent lamps are used in a track entry or belt entry or near track entries to illuminate special areas other than structures, the lamps shall be installed in weather-proof sockets located in positions such that the lamps will not come in contact with any combustible material. Lamps used in all other places must be of substantial construction and be fitted with a glass enclosure.
(b) Incandescent lamps within glass enclosures or fluorescent lamps may be used inside underground structures (except magazines used for the storage of explosives and detonators). In underground structures lighting circuits shall consist of cables installed on insulators or insulated wires installed in metallic conduit or metallic armor.
§ 75.523   Electric face equipment; deenergization.
An authorized representative of the Secretary may require in any mine that electric face equipment be provided with devices that will permit the equipment to be deenergized quickly in the event of an emergency.
§ 75.523-1   Deenergization of self-propelled electric face equipment installation requirements.
(a) Except as provided in paragraphs (b) and (c) of this section, all self-propelled electric face equipment which is used in the active workings of each underground coal mine on and after March 1, 1973, shall, in accordance with the schedule of time specified in paragraphs (a) (1) and (2) of this section, be provided with a device that will quickly deenergize the tramming motors of the equipment in the event of an emergency. The requirements of this paragraph (a) shall be met as follows:
(1) On and after December 15, 1974, for self-propelled cutting machines, shuttle cars, battery-powered machines, and roof drills and bolters;
(2) On and after February 15, 1975, for all other types of self-propelled electric face equipment.
(b) Self-propelled electric face equipment that is equipped with a substantially constructed cab which meets the requirements of this part, shall not be required to be provided with a device that will quickly deenergize the tramming motors of the equipment in the event of an emergency.
(c) An operator may apply to the Director of Technical Support, Mine Safety and Health Administration, Department of Labor, 201 12th Street South, Arlington, VA 22202-5452; 202-693-9440; for approval of the installation of devices to be used in lieu of devices that will quickly deenergize the tramming motors of self-propelled electric face equipment in the event of an emergency. The Director of Technical Support may approve such devices if he determines that the performance thereof will be no less effective than the performance requirements specified in § 75.523-2.
§ 75.523-2   Deenergization of self-propelled electric face equipment; performance requirements.
(a) Deenergization of the tramming motors of self-propelled electric face equipment, required by paragraph (a) of § 75.523-1, shall be provided by:
(1) Mechanical actuation of an existing pushbutton emergency stopswitch,
(2) Mechanical actuation of an existing lever emergency stopswitch, or
(3) The addition of a separate electromechanical switch assembly.
(b) The existing emergency stopswitch or additional switch assembly shall be actuated by a bar or lever which shall extend a sufficient distance in each direction to permit quick deenergization of the tramming motors of self-propelled electric face equipment from all locations from which the equipment can be operated.
(c) Movement of not more than 2 inches of the actuating bar or lever resulting from the application of not more than 15 pounds of force upon contact with any portion of the equipment operator's body at any point along the length of the actuating bar or lever shall cause deenergization of the tramming motors of the self-propelled electric face equipment.
§ 75.523-3   Automatic emergency-parking brakes.
(a) Except for personnel carriers, rubber-tired, self-propelled electric haulage equipment used in the active workings of underground coal mines shall be equipped with automatic emergency-parking brakes in accordance with the following schedule.
(1) On and after May 23, 1989—
(i) All new equipment ordered; and
(ii) All equipment originally furnished with or retrofitted with automatic emergency-parking brakes which meet the requirements of this section.
(2) On and after May 23, 1991, all other equipment.
(b) Automatic emergency-parking brakes shall—
(1) Be activated immediately by the emergency deenergization device required by 30 CFR 75.523-1 and 75.523-2;
(2) Engage automatically within 5.0 seconds when the equipment is deenergized;
(3) Safely bring the equipment when fully loaded to a complete stop on the maximum grade on which it is operated;
(4) Hold the equipment stationary despite any contraction of brake parts, exhaustion of any non-mechanical source of energy, or leakage; and
(5) Release only by a manual control that does not operate any other equipment function.
(c) Automatic emergency-parking brakes shall include a means in the equipment operator's compartment to—
(1) Apply the brakes manually without deenergizing the equipment; and
(2) Release and reengage the brakes without energizing the equipment.
(d) On and after November 24, 1989, rubber-tired, self-propelled electric face equipment not covered by paragraph (a) of this section shall be equipped with a means incorporated on the equipment and operable from each tramming station to hold the equipment stationary—
(1) On the maximum grade on which it is operated; and
(2) Despite any contraction of components, exhaustion of any non-mechanical source of energy, or leakage.
(e) The brake systems required by paragraphs (a) or (d) of this section shall be applied when the equipment operator is not at the controls of the equipment, except during movement of disabled equipment.
§ 75.524   Electric face equipment; electric equipment used in return air outby the last open crosscut; maximum level of alternating or direct electric current between frames of equipment.
The maximum level of alternating or direct electric current that exists between the frames of any two units of electric face equipment that come in contact with each other in the working places of a coal mine, or between the frames of any two units of electric equipment that come in contact with each other in return air outby the last open crosscut, shall not exceed one ampere as determined from the voltage measured across a 0.1 ohm resistor connected between the frames of such equipment.
§ 75.600   Trailing cables; flame resistance.
Trailing cables used in coal mines shall meet the requirements established by the Secretary for flame-resistant cables.
§ 75.600-1   Approved cables; flame resistance.
Cables shall be accepted or approved by MSHA as flame resistant.
§ 75.601   Short circuit protection of trailing cables.
Short circuit protection for trailing cables shall be provided by an automatic circuit breaker or other no less effective device approved by the Secretary of adequate current-interrupting capacity in each ungrounded conductor. Disconnecting devices used to disconnect power from trailing cables shall be plainly marked and identified and such devices shall be equipped or designed in such a manner that it can be determined by visual observation that the power is disconnected.
§ 75.601-1   Short circuit protection; ratings and settings of circuit breakers.
Circuit breakers providing short circuit protection for trailing cables shall be set so as not to exceed the maximum allowable instantaneous settings specified in this section; however, higher settings may be permitted by an authorized representative of the Secretary when he has determined that special applications are justified:
§ 75.601-2   Short circuit protection; use of fuses; approval by the Secretary.
Fuses shall not be employed to provide short circuit protection for trailing cables unless specifically approved by the Secretary.
§ 75.601-3   Short circuit protection; dual element fuses; current ratings; maximum values.
Dual element fuses having adequate current-interrupting capacity shall meet the requirements for short circuit protection of trailing cables as provided in § 75.601, however, the current ratings of such devices shall not exceed the maximum values specified in this section:
§ 75.602   Trailing cable junctions.
When two or more trailing cables junction to the same distribution center, means shall be provided to assure against connecting a trailing cable to the wrong size circuit breaker.
§ 75.603   Temporary splice of trailing cable.
One temporary splice may be made in any trailing cable. Such trailing cable may only be used for the next 24-hour period. No temporary splice shall be made in a trailing cable within 25 feet of the machine, except cable reel equipment. Temporary splices in trailing cables shall be made in a workmanlike manner and shall be mechanically strong and well insulated. Trailing cables or hand cables which have exposed wires or which have splices that heat or spark under load shall not be used. As used in this section, the term “splice” means the mechanical joining of one or more conductors that have been severed.
§ 75.604   Permanent splicing of trailing cables.
When permanent splices in trailing cables are made, they shall be:
(a) Mechanically strong with adequate electrical conductivity and flexibility;
(b) Effectively insulated and sealed so as to exclude moisture; and
(c) Vulcanized or otherwise treated with suitable materials to provide flame-resistant qualities and good bonding to the outer jacket.
(d) Made using splice kits accepted or approved by MSHA as flame resistant.
§ 75.605   Clamping of trailing cables to equipment.
Trailing cables shall be clamped to machines in a manner to protect the cables from damage and to prevent strain on the electrical connections.
§ 75.606   Protection of trailing cables.
Trailing cables shall be adequately protected to prevent damage by mobile equipment.
§ 75.607   Breaking trailing cable and power cable connections.
Trailing cable and power cable connections to junction boxes shall not be made or broken under load.
§ 75.700   Grounding metallic sheaths, armors, and conduits enclosing power conductors.
All metallic sheaths, armors, and conduits enclosing power conductors shall be electrically continuous throughout and shall be grounded by methods approved by an authorized representative of the Secretary.
§ 75.700-1   Approved methods of grounding.
Metallic sheaths, armors and conduits in resistance grounded systems where the enclosed conductors are a part of the system will be approved if a solid connection is made to the neutral conductor; in all other systems, the following methods of grounding will be approved:
(a) A solid connection to a borehole casing having low resistance to earth;
(b) A solid connection to metal waterlines having low resistance to earth;
(c) A solid connection to a grounding conductor, other than the neutral conductor of a resistance grounded system, extending to a low resistance ground field located on the surface;
(d) Any other method of grounding, approved by an authorized representative of the Secretary, which ensures that there is no difference in potential between such metallic enclosures and the earth.
§ 75.701   Grounding metallic frames, casings, and other enclosures of electric equipment.
Metallic frames, casings, and other enclosures of electric equipment that can become “alive” through failure of insulation or by contact with energized parts shall be grounded by methods approved by an authorized representative of the Secretary.
§ 75.701-1   Approved methods of grounding of equipment receiving power from ungrounded alternating current power systems.
For purposes of grounding metallic frames, casings and other enclosures of equipment receiving power from ungrounded alternating current power systems, the following methods of grounding will be approved:
(a) A solid connection between the metallic frame, casing, or other metal enclosure and the grounded metallic sheath, armor, or conduit enclosing the power conductor feeding the electrical equipment enclosed;
(b) A solid connection to a borehole casing having low resistance to earth;
(c) A solid connection to metal waterlines having low resistance to earth;
(d) A solid connection to a grounding conductor extending to a low resistance ground field located on the surface;
(e) Any other method of grounding, approved by an authorized representative of the Secretary, which ensures that there is no difference in potential between such metal enclosures and the earth.
§ 75.701-2   Approved method of grounding metallic frames, casings and other enclosures receiving power from single-phase 110-220-volt circuit.
In instances where single-phase 110-220-volt circuits are used to feed electrical equipment, the only method of grounding that will be approved is the connection of all metallic frames, casings and other enclosures of such equipment to a separate grounding conductor which establishes a continuous connection to a grounded center tap of the transformer.
§ 75.701-3   Approved methods of grounding metallic frames, casings and other enclosures of electric equipment receiving power from direct current power systems with one polarity grounded.
For the purpose of grounding metallic frames, casings and enclosures of any electric equipment or device-receiving power from a direct-current power system with one polarity grounded, the following methods of grounding will be approved:
(a) A solid connection to the mine track;
(b) A solid connection to the grounded power conductor of the system;
(c) Silicon diode grounding; however, this method shall be employed only when such devices are installed in accordance with the requirements set forth in paragraph (d) of § 75.703-3; and
(d) Any other method, approved by an authorized representative of the Secretary, which insures that there is no difference in potential between such metal enclosures and the earth.
§ 75.701-4   Grounding wires; capacity of wires.
Where grounding wires are used to ground metallic sheaths, armors, conduits, frames, casings, and other metallic enclosures, such grounding wires will be approved if:
(a) The cross-sectional area (size) of the grounding wire is at least one-half the cross-sectional area (size) of the power conductor where the power conductor used is No. 6 A.W.G., or larger.
(b) Where the power conductor used is less than No. 6 A.W.G., the cross-sectional area (size) of the grounding wire is equal to the cross-sectional area (size) of the power conductor.
§ 75.701-5   Use of grounding connectors.
The attachment of grounding wires to a mine track or other grounded power conductor will be approved if separate clamps, suitable for such purpose, are used and installed to provide a solid connection.
§ 75.702   Protection other than grounding.
Methods other than grounding which provide no less effective protection may be permitted by the Secretary or his authorized representative.
§ 75.702-1   Protection other than grounding; approved by an authorized representative of the Secretary.
Under this subpart no method other than grounding may be used to ensure against a difference in potential between metallic sheaths, armors and conduits, enclosing power conductors and frames, casings and metal enclosures of electric equipment, and the earth, unless approved by an authorized representative of the Secretary.
§ 75.703   Grounding offtrack direct-current machines and the enclosures of related detached components.
The frames of all offtrack direct-current machines and the enclosures of related detached components shall be effectively grounded, or otherwise maintained at no less safe voltages, by methods approved by an authorized representative of the Secretary.
§ 75.703-1   Approved method of grounding.
In instances where the metal frames both of an offtrack direct-current machine and of the metal frames of its component parts are grounded to the same grounding medium the requirements of § 75.703 will be met.
§ 75.703-2   Approved grounding mediums.
For purposes of grounding offtrack direct-current machines, the following grounding mediums are approved:
(a) The grounded polarity of the direct-current power system feeding such machines; or,
(b) The alternating current grounding medium where such machines are fed by an ungrounded direct-current power system originating in a portable rectifier receiving its power from a section power center. However, when such a medium is used, a separate grounding conductor must be employed.
§ 75.703-3   Approved methods of grounding offtrack mobile, portable and stationary direct-current machines.
In grounding offtrack direct-current machines and the enclosures of their component parts, the following methods of grounding will meet the requirements of § 75.703:
(a) The use of a separate grounding conductor located within the trailing cable of mobile and portable equipment and connected between such equipment and the direct-current grounding medium;
(b) The use of a separate ground conductor located within the direct-current power cable feeding stationary equipment and connected between such stationary equipment and the direct-current grounding medium;
(c) The use of a separate external ground conductor connected between stationary equipment and the direct-current grounding medium; or,
(d) The use of silicon diodes; however, the installation of such devices shall meet the following minimum requirements:
(1) Installation of silicon diodes shall be restricted to electric equipment receiving power from a direct-current system with one polarity grounded;
(2) Where such diodes are used on circuits having a nominal voltage rating of 250, they must have a forward current rating of 400 amperes or more, and have a peak inverse voltage rating of 400 or more;
(3) Where such diodes are used on circuits having a nominal voltage rating of 550, they must have a forward current rating of 250 amperes or more, and have a peak inverse voltage rating of 800 or more;
(4) Where fuses approved by the Secretary are used at the outby end of a trailing cable connected to electrical equipment employing silicon diodes, the rating of such fuses must not exceed 150 percent of the nominal current rating of the grounding diodes;
(5) Where circuit breakers are used at the outby end of a trailing cable connected to electrical equipment employing silicon diodes, the instantaneous trip setting shall not exceed 300 percent of the nominal current rating of the grounding diode;
(6) Overcurrent devices must be used and installed in such a manner that the operating coil circuit of the main contactor will open when a fault current with a value of 25 percent or less of the diode rating flows through the diode;
(7) The silicon diode installed must be suitable to the grounded polarity of the power system in which it is used and its threaded base must be solidly connected to the machine frame on which it is installed;
(8) In addition to the grounding diode, a polarizing diode must be installed in the machine control circuit to prevent operation of the machine when the polarity of a trailing cable is reversed;
(9) When installed on permissible equipment, all grounding diodes, overcurrent devices, and polarizing diodes must be placed in explosion proof compartments;
(10) When grounding diodes are installed on a continuous miner, their nominal diode current rating must be at least 750 amperes or more; and,
(11) All grounding diodes shall be tested, examined and maintained as electrical equipment in accordance with the provisions of § 75.512.
§ 75.703-4   Other methods of protecting offtrack direct-current equipment; approved by an authorized representative of the Secretary.
Other methods of maintaining safe voltage by preventing a difference between the frames of offtract direct-current machines and the earth must be approved by an authorized representative of the Secretary.
§ 75.704   Grounding frames of stationary high-voltage equipment receiving power from ungrounded delta systems.
The frames of all stationary high-voltage equipment receiving power from ungrounded delta systems shall be grounded by methods approved by an authorized representative of the Secretary.
§ 75.704-1   Approved methods of grounding.
The methods of grounding stated in § 75.701-1 will also be approved with respect to the grounding of frames of high-voltage equipment referred to in § 75.704.
§ 75.705   Work on high-voltage lines; deenergizing and grounding.
High-voltage lines, both on the surface and underground, shall be deenergized and grounded before work is performed on them, except that repairs may be permitted, in the case of energized surface high-voltage lines, if such repairs are made by a qualified person in accordance with procedures and safeguards, including, but not limited to, a requirement that the operator of such mine provide, test, and maintain protective devices in making such repairs, to be prescribed by the Secretary prior to March 30, 1970.
§ 75.705-1   Work on high-voltage lines.
(a) Section 75.705 specifically prohibits work on energized high-voltage lines underground;
(b) No high-voltage line, either on the surface or underground, shall be regarded as deenergized for the purpose of performing work on it, until it has been determined by a qualified person (as provided in § 75.153) that such high-voltage line has been deenergized and grounded. Such qualified person shall by visual observation (1) determine that the disconnecting devices on the high-voltage circuit are in open position and (2) ensure that each ungrounded conductor of the high-voltage circuit upon which work is to be done is properly connected to the system-grounding medium. In the case of resistance grounded or solid wye-connected systems, the neutral wire is the system-grounding medium. In the case of an ungrounded power system, either the steel armor or conduit enclosing the system or a surface grounding field is a system grounding medium;
(c) No work shall be performed on any high-voltage line on the surface which is supported by any pole or structure which also supports other high-voltage lines until: (1) All lines supported on the pole or structure are deenergized and grounded in accordance with all of the provisions of this section which apply to the repair of energized surface high-voltage lines; or (2) the provisions of §§ 75.705-2 through 75.705-10 have been complied with, with respect to all lines, which are supported on the pole or structure.
(d) Work may be performed on energized surface high-voltage lines only in accordance with the provisions of §§ 75.705-2 through 75.705-10, inclusive.
§ 75.705-2   Repairs to energized surface high-voltage lines.
An energized high-voltage surface line may be repaired only when
(a) The operator has determined that:
(1) Such repairs cannot be scheduled during a period when the power circuit could be properly deenergized and grounded;
(2) Such repairs will be performed on power circuits with a phase-to-phase nominal voltage no greater than 15,000 volts;
(3) Such repairs on circuits with a phase-to-phase nominal voltage of 5,000 volts or more will be performed only with the use of live line tools;
(4) Weather conditions will not interfere with such repairs or expose those persons assigned to such work to an imminent danger; and
(b) The operator has designated a person qualified under the provisions of § 75.154 as the person responsible for carrying out such repairs and such person, in order to ensure protection for himself and other qualified persons assigned to perform such repairs from the hazards of such repair, has prepared and filed with the operator:
(1) A general description of the nature and location of the damage or defect to be repaired;
(2) The general plan to be followed in making such repairs;
(3) A statement that a briefing of all qualified persons assigned to make such repairs was conducted informing them of the general plan, their individual assignments, and the dangers inherent in such assignments;
(4) A list of the proper protective equipment and clothing that will be provided; and
(5) Such other information as the person designated by the operator feels necessary to describe properly the means or methods to be employed in such repairs.
§ 75.705-3   Work on energized high-voltage surface lines; reporting.
Any operator designating and assigning qualified persons to perform repairs on energized high-voltage surface lines under the provisions of § 75.705-2 shall maintain a record of such repairs. Such record shall contain a notation of the time, date, location, and general nature of the repairs made, together with a copy of the information filed with the operator by the qualified person designated as responsible for performing such repairs.
§ 75.705-4   Simultaneous repairs.
When two or more persons are working on an energized high-voltage surface line simultaneously, and any one of them is within reach of another, such persons shall not be allowed to work on different phases or on equipment with different potentials.
§ 75.705-5   Installation of protective equipment.
Before repair work on energized high-voltage surface lines is begun, protective equipment shall be used to cover all bare conductors, ground wires, guys, telephone lines, and other attachments in proximity to the area of planned repairs. Such protective equipment shall be installed from a safe position below the conductors or other apparatus being covered. Each rubber protective device employed in the making of repairs shall have a dielectric strength of 20,000 volts, or more.
§ 75.705-6   Protective clothing; use and inspection.
All persons performing work on energized high-voltage surface lines shall wear protective rubber gloves, sleeves, and climber guards if climbers are worn. Protective rubber gloves shall not be worn wrong side out or without protective leather gloves. Protective devices worn by a person assigned to perform repairs on high-voltage surface lines shall be worn continuously from the time he leaves the ground until he returns to the ground, and, if such devices are employed for extended periods, such person shall visually inspect the equipment assigned him for defects before each use and, in no case, less than twice each day.
§ 75.705-7   Protective equipment; inspection.
Each person shall visually inspect protective equipment and clothing provided him in connection with work on high-voltage surface lines before using such equipment and clothing, and any equipment or clothing containing any defect or damage shall be discarded and replaced with proper protective equipment or clothing prior to the performance of any electrical work on such lines.
§ 75.705-8   Protective equipment; testing and storage.
(a) All rubber protective equipment used on work on energized high-voltage surface lines shall be electrically tested by the operator in accordance with ASTM standards, Part 28, published February 1968, and such testing shall be conducted in accordance with the following schedule:
(1) Rubber gloves, once each month;
(2) Rubber sleeves, once every 3 months;
(3) Rubber blankets, once every 6 months;
(4) Insulator hoods and line hose, once a year; and
(5) Other electric protective equipment, once a year.
(b) Rubber gloves shall not be stored wrong side out. Blankets shall be rolled when not in use, and line hose and insulator hoods shall be stored in their natural position and shape.
§ 75.705-9   Operating disconnecting or cutout switches.
Disconnecting or cutout switches on energized high-voltage surface lines shall be operated only with insulated sticks, fuse tongs, or pullers which are adequately insulated and maintained to protect the operator from the voltage to which he is exposed. When such switches are operated from the ground, the person operating such devices shall wear protective rubber gloves.
§ 75.705-10   Tying into energized high-voltage surface circuits.
If the work of forming an additional circuit by tying into an energized high-voltage surface line is performed from the ground, any person performing such work must wear and employ all of the protective equipment and clothing required under the provisions of §§ 75.705-5 and 75.705-6. In addition, the insulated stick used by such person must have been designed for such purpose and must be adequately insulated and be maintained to protect such person from the voltage to which he is exposed.
§ 75.705-11   Use of grounded messenger wires; ungrounded systems.
Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger wires used to suspend the cables of such systems may be used as a grounding medium.
§ 75.706   Deenergized underground power circuits; idle days—idle shifts.
When not in use, power circuits underground shall be deenergized on idle days and idle shifts, except that rectifiers and transformers may remain energized.
§ 75.800   High-voltage circuits; circuit breakers.
High-voltage circuits entering the underground area of any coal mine shall be protected by suitable circuit breakers of adequate interrupting capacity which are properly tested and maintained as prescribed by the Secretary. Such breakers shall be equipped with devices to provide protection against under-voltage grounded phase, short circuit, and overcurrent.
§ 75.800-1   Circuit breakers; location.
Circuit breakers protecting high-voltage circuits entering an underground area of any coal mine shall be located on the surface and in no case installed either underground or within a drift.
§ 75.800-2   Approved circuit schemes.
The following circuit schemes will be regarded as providing the necessary protection to the circuits required by § 75.800:
(a) Ground check relays may be used for undervoltage protection if the relay coils are designed to trip the circuit breaker when line voltage decreases to 40 percent to 60 percent of the nominal line voltage;
(b) Ground trip relays on resistance grounded systems will be acceptable as grounded phase protection;
(c) One circuit breaker may be used to protect two or more branch circuits, if the circuit breaker is adjusted to afford overcurrent protection for the smallest conductor.
§ 75.800-3   Testing, examination and maintenance of circuit breakers; procedures.
(a) Circuit breakers and their auxiliary devices protecting underground high-voltage circuits shall be tested and examined at least once each month by a person qualified as provided in § 75.153;
(b) Tests shall include: (1) Breaking continuity of the ground check conductor, where ground check monitoring is used; and
(2) Actuating at least two (2) of the auxiliary protective relays.
(c) Examination shall include visual observation of all components of the circuit breaker and its auxiliary devices, and such repairs or adjustments as are indicated by such tests and examinations shall be carried out immediately.
§ 75.800-4   Testing, examination, and maintenance of circuit breakers; record.
(a) Recordkeeping. The operator shall make a record of each test, examination, repair, or adjustment of all circuit breakers protecting high-voltage circuits which enter any underground area of the mine.
(b) Record security. These records shall be made 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.
(c) Retention and access. These records shall be retained at a surface location at the mine for at least one year and shall be made available to authorized representatives of the Secretary, the representative of miners, and other interested persons.
§ 75.801   Grounding resistors.
The grounding resistor, where required, shall be of the proper ohmic value to limit the voltage drop in the grounding circuit external to the resistor to not more than 100 volts under fault conditions. The grounding resistor shall be rated for maximum fault current continuously and insulated from ground for a voltage equal to the phase-to-phase voltage of the system.
§ 75.802   Protection of high-voltage circuits extending underground.
(a) Except as provided in paragraph (b) of this section, high-voltage circuits extending underground and supplying portable, mobile, or, stationary high-voltage equipment shall contain either a direct or derived neutral which shall be grounded through a suitable resistor at the source transformers, and a grounding circuit, originating at the grounded side of the grounding resistor, shall extend along with the power conductors and serve as a grounding conductor for the frames of all high-voltage equipment supplied power from that circuit.
(b) Notwithstanding the requirements of paragraph (a) of this section, the Secretary or his authorized representative may permit ungrounded high-voltage circuits to be extended underground to feed stationary electric equipment if:
(1) Such circuits are either steel armored or installed in grounded, rigid steel conduit throughout their entire length; or,
(2) The voltage of such circuits is nominally 2,400 volts or less phase-to-phase and the cables used in such circuits are equipped with metallic shields around each power conductor, and contain one or more ground conductors having a total cross sectional area of not less than one-half the power conductor; and,
(3) Upon a finding by the Secretary or his authorized representative that the use of the circuits described in paragraphs (b) (1) and (2) of this section does not pose a hazard to the miners.
(c) Within 100 feet of the point on the surface where high-voltage circuits enter the underground portion of the mine, disconnecting devices shall be installed and so equipped or designed in such a manner that it can be determined by visual observation that the power is disconnected, except that the Secretary or his authorized representative may permit such devices to be installed at a greater distance from such area of the mine if he determines, based on existing physical conditions, that such installation will be more accessible at a greater distance and will not pose any hazard to the miners.
§ 75.803   Fail safe ground check circuits on high-voltage resistance grounded systems.
On and after September 30, 1970, high-voltage, resistance grounded systems shall include a fail safe ground check circuit to monitor continuously the grounding circuit to assure continuity and the fail safe ground check circuit shall cause the circuit breaker to open when either the ground or pilot check wire is broken, or other no less effective device approved by the Secretary or his authorized representative to assure such continuity, except that an extension of time, not in excess of 12 months, may be permitted by the Secretary on a mine-by-mine basis if he determines that such equipment is not available.
§ 75.803-1   Maximum voltage ground check circuits.
The maximum voltage used for ground check circuits under § 75.803 shall not exceed 96 volts.
§ 75.803-2   Ground check systems not employing pilot check wires; approval by the Secretary.
Ground check systems not employing pilot check wires will be approved only if it is determined that the system includes a fail safe design causing the circuit breaker to open when ground continuity is broken.
§ 75.804   Underground high-voltage cables.
(a) Underground high-voltage cables used in resistance grounded systems shall be equipped with metallic shields around each power conductor with one or more ground conductors having a total cross sectional area of not less than one-half the power conductor, and with an insulated external conductor not smaller than No. 8 (A.W.G.) or an insulated internal ground check conductor not smaller than No. 10 (A.W.G.) for the ground continuity check circuit.
(b) All such cables shall be adequate for the intended current and voltage. Splices made in such cables shall provide continuity of all components.
§ 75.805   Couplers.
Couplers that are used with medium-voltage or high-voltage power circuits shall be of the three-phase type with a full metallic shell, except that the Secretary may permit, under such guidelines as he may prescribe, no less effective couplers constructed of materials other than metal. Couplers shall be adequate for the voltage and current expected. All exposed metal on the metallic couplers shall be grounded to the ground conductor in the cable. The coupler shall be constructed so that the ground check continuity conductor shall be broken first and the ground conductors shall be broken last when the coupler is being uncoupled.
§ 75.806   Connection of single-phase loads.
Single-phase loads, such as transformer primaries, shall be connected phase-to-phase.
§ 75.807   Installation of high-voltage transmission cables.
All underground high-voltage transmission cables shall be installed only in regularly inspected air courses and haulageways, and shall be covered, buried, or placed so as to afford protection against damage, guarded where men regularly work or pass under them unless they are 6 1/2 feet or more above the floor or rail, securely anchored, properly insulated, and guarded at ends, and covered, insulated, or placed to prevent contact with trolley wires and other low-voltage circuits.
§ 75.808   Disconnecting devices.
Disconnecting devices shall be installed at the beginning of branch lines in high-voltage circuits and equipped or designed in such a manner that it can be determined by visual observation that the circuit is deenergized when the switches are open.
§ 75.809   Identification of circuit breakers and disconnecting switches.
Circuit breakers and disconnecting switches underground shall be marked for identification.
§ 75.810   High-voltage trailing cables; splices.
In the case of high-voltage cables used as trailing cables, temporary splices shall not be used and all permanent splices shall be made in accordance with § 75.604. Terminations and splices in all other high-voltage cables shall be made in accordance with the manufacturer's specifications.
§ 75.811   High-voltage underground equipment; grounding.
Frames, supporting structures and enclosures of stationary, portable, or mobile underground high-voltage equipment and all high-voltage equipment supplying power to such equipment receiving power from resistance grounded systems shall be effectively grounded to the high-voltage ground.
§ 75.812   Movement of high-voltage power centers and portable transformers; permit.
Power centers and portable transformers shall be deenergized before they are moved from one location to another, except that, when equipment powered by sources other than such centers or transformers is not available, the Secretary may permit such centers and transformers to be moved while energized, if he determines that another equivalent or greater hazard may otherwise be created, and if they are moved under the supervision of a qualified person, and if such centers and transformers are examined prior to such movement by such person and found to be grounded by methods approved by an authorized representative of the Secretary and otherwise protected from hazards to the miner. A record shall be kept of such examinations. High-voltage cables, other than trailing cables, shall not be moved or handled at any time while energized, except that, when such centers and transformers are moved while energized as permitted under this section, energized high-voltage cables attached to such centers and transformers may be moved only by a qualified person and the operator of such mine shall require that such person wear approved and tested insulated wireman's gloves.
§ 75.812-1   Qualified person.
A person who meets the requirements of § 75.153 is a qualified person within the meaning of § 75.812.
§ 75.812-2   High-voltage power centers and transformers; record of examination.
The operator shall maintain a record of all examinations conducted in accordance with § 75.812. Such record shall be kept in a book approved by the Secretary.
§ 75.813   High-voltage longwalls; scope.
Sections 75.814 through 75.822 of this part are electrical safety standards that apply to high-voltage longwall circuits and equipment. All other existing standards in 30 CFR must also apply to these longwall circuits and equipment where appropriate.
§ 75.814   Electrical protection.
(a) High-voltage circuits must be protected against short circuits, overloads, ground faults, and undervoltages by circuit-interrupting devices of adequate interrupting capacity as follows:
(1) Current settings of short-circuit protective devices must not exceed the setting specified in approval documentation, or seventy-five percent of the minimum available phase-to-phase short-circuit current, whichever is less.
(2) Time-delay settings of short-circuit protective devices used to protect any cable extending from the section power center to a motor-starter enclosure must not exceed the settings specified in approval documentation, or 0.25-second, whichever is less. Time delay settings of short-circuit protective devices used to protect motor and shearer circuits must not exceed the settings specified in approval documentation, or 3 cycles, whichever is less.
(3) Ground-fault currents must be limited by a neutral grounding resistor to not more than—
(i) 6.5 amperes when the nominal voltage of the power circuit is 2,400 volts or less; or
(ii) 3.75 amperes when the nominal voltage of the power circuit exceeds 2,400 volts.
(4) High-voltage circuits extending from the section power center must be provided with—
(i) Ground-fault protection set to cause deenergization at not more than 40 percent of the current rating of the neutral grounding resistor;
(ii) A backup ground-fault detection device to cause deenergization when a ground fault occurs with the neutral grounding resistor open; and
(iii) Thermal protection for the grounding resistor that will deenergize the longwall power center if the resistor is subjected to a sustained ground fault. The thermal protection must operate at either 50 percent of the maximum temperature rise of the grounding resistor, or 150 °C (302 °F), whichever is less, and must open the ground-wire monitor circuit for the high-voltage circuit supplying the section power center. The thermal protection must not be dependent upon control power and may consist of a current transformer and overcurrent relay.
(5) High-voltage motor and shearer circuits must be provided with instantaneous ground-fault protection set at not more than 0.125-ampere.
(6) Time-delay settings of ground-fault protective devices used to provide coordination with the instantaneous ground-fault protection of motor and shearer circuits must not exceed 0.25-second.
(7) Undervoltage protection must be provided by a device which operates on loss of voltage to cause and maintain the interruption of power to a circuit to prevent automatic restarting of the equipment.
(b) Current transformers used for the ground-fault protection specified in paragraphs (a)(4)(i) and (5) of this section must be single window-type and must be installed to encircle all three phase conductors. Equipment safety grounding conductors must not pass through or be connected in series with ground-fault current transformers.
(c) Each ground-fault current device specified in paragraphs (a)(4)(i) and (5) of this section must be provided with a test circuit that will inject a primary current of 50 percent or less of the current rating of the grounding resistor through the current transformer and cause each corresponding circuit-interrupting device to open.
(d) Circuit-interrupting devices must not reclose automatically.
(e) Where two or more high-voltage cables are used to supply power to a common bus in a high-voltage enclosure, each cable must be provided with ground-wire monitoring. The ground-wire monitoring circuits must cause deenergization of each cable when either the ground-monitor or grounding conductor(s) of any cable become severed or open. On or after May 10, 2002, parallel connected cables on newly installed longwalls must be protected as follows:
(1) When one circuit-interrupting device is used to protect parallel connected cables, the circuit-interrupting device must be electrically interlocked with the cables so that the device will open when any cable is disconnected; or
(2) When two or more parallel circuit-interrupting devices are used to protect parallel connected cables, the circuit-interrupting devices must be mechanically and electrically interlocked. Mechanical interlocking must cause all devices to open simultaneously and electrical interlocking must cause all devices to open when any cable is disconnected.
§ 75.815   Disconnect devices.
(a) The section power center must be equipped with a main disconnecting device installed to deenergize all cables extending to longwall equipment when the device is in the “open” position. See Figures I-1 and I-2 in Appendix A to this subpart I.
(b) Disconnecting devices for motor-starter enclosures must be maintained in accordance with the approval requirements of paragraph (f) of § 18.53 of part 18 of this chapter. The compartment for the disconnect device must be provided with a caution label to warn miners against entering the compartment before deenergizing the incoming high-voltage circuits to the compartment.
(c) Disconnecting devices must be rated for the maximum phase-to-phase voltage of the circuit in which they are installed, and for the full-load current of the circuit that is supplied power through the device.
(d) Each disconnecting device must be designed and installed so that—
(1) Visual observation determines that the contacts are open without removing any cover;
(2) All load power conductors can be grounded when the device is in the “open” position; and
(3) The device can be locked in the “open” position.
(e) Disconnecting devices, except those installed in explosion-proof enclosures, must be capable of interrupting the full-load current of the circuit or designed and installed to cause the current to be interrupted automatically prior to the opening of the contacts of the device. Disconnecting devices installed in explosion-proof enclosures must be maintained in accordance with the approval requirements of paragraph (f)(2)(iv) of § 18.53 of part 18 of this chapter.
§ 75.816   Guarding of cables.
(a) High-voltage cables must be guarded at the following locations:
(1) Where persons regularly work or travel over or under the cables.
(2) Where the cables leave cable handling or support systems to extend to electric components.
(b) Guarding must minimize the possibility of miners contacting the cables and protect the cables from damage. The guarding must be made of grounded metal or nonconductive flame-resistant material.
§ 75.817   Cable handling and support systems.
Longwall mining equipment must be provided with cable-handling and support systems that are constructed, installed and maintained to minimize the possibility of miners contacting the cables and to protect the high-voltage cables from damage.
§ 75.818   Use of insulated cable handling equipment.
(a) Energized high-voltage cables must not be handled except when motor or shearer cables need to be trained. When cables need to be trained, high-voltage insulated gloves, mitts, hooks, tongs, slings, aprons, or other personal protective equipment capable of providing protection against shock hazard must be used to prevent direct contact with the cable.
(b) High-voltage insulated gloves, sleeves, and other insulated personal protective equipment must—
(1) Have a voltage rating of at least Class 1 (7,500 volts) that meets or exceeds ASTM F496-97, “Standard Specification for In-Service Care of Insulating Gloves and Sleeves” (1997).
(2) Be examined before each use for visible signs of damage;
(3) Be removed from the underground area of the mine or destroyed when damaged or defective; and
(4) Be electrically tested every 6 months in accordance with publication ASTM F496-97. ASTM F496-97 (Standard Specification for In-Service Care of Insulating Gloves and Sleeves, 1997) is incorporated by reference and may be inspected at any MSHA Coal Mine Safety and Health District Office, or at MSHA's Office of Standards, Regulations, and Variances, 201 12th Street South, Arlington, VA 22202-5452; 202-693-9440; and 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. In addition, copies of the document can be purchased from the American Society for Testing and Materials, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959; 610-832-9500; http://www.astm.org. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
§ 75.819   Motor-starter enclosures; barriers and interlocks.
Compartment separation and cover interlock switches for motor-starter enclosures must be maintained in accordance with the approval requirements of paragraphs (a) and (b) of § 18.53 of part 18 of this chapter.
§ 75.820   Electrical work; troubleshooting and testing.
(a) Electrical work on all circuits and equipment associated with high-voltage longwalls must be performed only by persons qualified under § 75.153 to perform electrical work on all circuits and equipment.
(b) Prior to performing electrical work, except for troubleshooting and testing of energized circuits and equipment as provided for in paragraph (d) of this section, a qualified person must do the following:
(1) Deenergize the circuit or equipment with a circuit-interrupting device.
(2) Open the circuit disconnecting device. On high-voltage circuits, ground the power conductors until work on the circuit is completed.
(3) Lock out the disconnecting device with a padlock. When more than one qualified person is performing work, each person must install an individual padlock.
(4) Tag the disconnecting device to identify each person working and the circuit or equipment on which work is being performed.
(c) Each padlock and tag must be removed only by the person who installed them, except that, if that person is unavailable at the mine, the lock and tag may be removed by a person authorized by the operator, provided—
(1) The authorized person is qualified under paragraph (a) of this section; and
(2) The operator ensures that the person who installed the lock and tag is aware of the removal before that person resumes work on the affected circuit or equipment.
(d) Troubleshooting and testing of energized circuits must be performed only—
(1) On low- and medium-voltage circuits;
(2) When the purpose of troubleshooting and testing is to determine voltages and currents; and
(3) By persons qualified to perform electrical work and who wear protective gloves on circuits that exceed 40 volts in accordance with the following table:
(4) Rubber insulating gloves must be rated at least for the nominal voltage of the circuit when the voltage of the circuit exceeds 120 volts nominal and is not intrinsically safe.
(e) Before troubleshooting and testing a low- or medium-voltage circuit contained in a compartment with a high-voltage circuit, the high-voltage circuit must be deenergized, disconnected, grounded, locked out and tagged in accordance with paragraph (b) of this section.
(f) Prior to the installation or removal of conveyor belt structure, high-voltage cables extending from the section power center to longwall equipment and located in the belt entries must be:
(1) Deenergized; or
(2) Guarded in accordance with § 75.816 of this part, at the location where the belt structure is being installed or removed; or
(3) Located at least 6.5 feet above the mine floor.
§ 75.821   Testing, examination and maintenance.
(a) At least once every 7 days, a person qualified in accordance with § 75.153 to perform electrical work on all circuits and equipment must test and examine each unit of high-voltage longwall equipment and circuits to determine that electrical protection, equipment grounding, permissibility, cable insulation, and control devices are being properly maintained to prevent fire, electrical shock, ignition, or operational hazards from existing on the equipment. Tests must include activating the ground-fault test circuit as required by § 75.814(c).
(b) Each ground-wire monitor and associated circuits must be examined and tested at least once each 30 days to verify proper operation and that it will cause the corresponding circuit-interrupting device to open.
(c) When examinations or tests of equipment reveal a fire, electrical shock, ignition, or operational hazard, the equipment must be removed from service immediately or repaired immediately.
(d) At the completion of examinations and tests required by this section, the person who makes the examinations and tests must certify by signature and date that they have been conducted. A record must be made of any unsafe condition found and any corrective action taken. Certifications and records must be kept for at least one year and must be made available for inspection by authorized representatives of the Secretary and representatives of miners.
§ 75.822   Underground high-voltage longwall cables.
In addition to the high-voltage cable design specifications in § 75.804 of this part, high-voltage cables for use on longwalls may be a type SHD cable with a center ground-check conductor no smaller than a No. 16 AWG stranded conductor. The cables must be MSHA accepted as flame-resistant under part 18 or approved under subpart K of part 7.
§ 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 § 75.153. Other standards in 30 CFR apply to these circuits and equipment where appropriate.
§ 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 °F (150 °C), whichever is less. Thermal protection must not be dependent on control power and may consist of a current transformer and over-current 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.
§ 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.
§ 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 (§ 75.804) or have a stranded center ground-check conductor not smaller than a No. 16 A.W.G.
§ 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).
§ 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.
§ 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 (§ 75.812) and as follows:
(1) The power source must not be located in areas where permissible equipment is required;
(2) The continuous mining machine must not be used for mining or cutting purposes, unless a power center is used in accordance with §§ 75.823 through 75.828 and §§ 75.830 through 75.833;
(3) Low-, medium-, and high-voltage cables must comply with §§ 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 §§ 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 § 75.832(f).
(c) Power sources. In addition to the power center specified in § 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.
(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 § 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.
§ 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 § 75.810; and
(iv) Using only MSHA-approved high-voltage kits that include instructions for outer-jacket repairs and splices.
(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.
§ 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:
(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.
§ 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.
(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.
§ 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, P.O. Box C700, West Conshohocken, PA 19428-2959, call 610-832-9500 or go to http://www.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, 201 12th Street South, Arlington, VA 22202-5452; 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.
§ 75.834   Training.
In addition to existing part 48 task training, hazard training, training for qualified persons under existing § 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.
§ 75.900   Low- and medium-voltage circuits serving three-phase alternating current equipment; circuit breakers.
Low- and medium-voltage power circuits serving three-phase alternating current equipment shall be protected by suitable circuit breakers of adequate interrupting capacity which are properly tested and maintained as prescribed by the Secretary. Such breakers shall be equipped with devices to provide protection against undervoltage, grounded phase, short circuit, and overcurrent.
§ 75.900-1   Circuit breakers; location.
Circuit breakers used to protect low-and medium-voltage circuits underground shall be located in areas which are accessible for inspection, examination, and testing, have safe roofs, and are clear of any moving equipment used in haulageways.
§ 75.900-2   Approved circuit schemes.
The following circuit schemes will be regarded as providing the necessary protection to the circuit required by § 75.900:
(a) Ground check relays may be used for undervoltage protection if the relay coils are designed to trip the circuit breaker when line voltage decreases to 40 to 60 percent of the nominal line voltage.
(b) One undervoltage device installed in the main secondary circuit at the source transformer may be used to provide undervoltage protection for each circuit that receives power from that transformer.
(c) One circuit breaker may be used to protect two or more branch circuits if the circuit breaker is adjusted to afford overcurrent protection for the smallest conductor.
(d) Circuit breakers with shunt trip, series trip or undervoltage release devices may be used if the tripping elements of such devices are selected or adjusted in accordance with the settings listed in the tables of the National Electric Code, 1968.
§ 75.900-3   Testing, examination, and maintenance of circuit breakers; procedures.
Circuit breakers protecting low- and medium-voltage alternating current circuits serving three-phase alternating current equipment and their auxiliary devices shall be tested and examined at least once each month by a person qualified as provided in § 75.153. In performing such tests, actuating any of the circuit breaker auxiliaries or control circuits in any manner which causes the circuit breaker to open, shall be considered a proper test. All components of the circuit breaker and its auxiliary devices shall be visually examined and such repairs or adjustments as are indicated by such tests and examinations shall be carried out immediately.
§ 75.900-4   Testing, examination, and maintenance of circuit breakers; record.
The operator of any coal mine shall maintain a written record of each test, examination, repair, or adjustment of all circuit breakers protecting low- and medium-voltage circuits serving three-phase alternating current equipment used in the mine. Such record shall be kept in a book approved by the Secretary.
§ 75.901   Protection of low- and medium-voltage three-phase circuits used underground.
(a) Low- and medium-voltage three-phase alternating-current circuits used underground shall contain either a direct or derived neutral which shall be grounded through a suitable resistor at the power center, and a grounding circuit, originating at the grounded side of the grounding resistor, shall extend along with the power conductors and serve as a grounding conductor for the frames of all the electrical equipment supplied power from that circuit, except that the Secretary or his authorized representative may permit ungrounded low- and medium-voltage circuits to be used underground to feed such stationary electrical equipment if such circuits are either steel armored or installed in grounded rigid steel conduit throughout their entire length. The grounding resistor, where required, shall be of the proper ohmic value to limit the ground fault current to 25 amperes. The grounding resistor shall be rated for maximum fault current continuously and insulated from ground for a voltage equal to the phase-to-phase voltage of the system.
(b) Diesel-powered electrical generators used as an alternative to power centers for the purpose of moving equipment in, out, and around the mine, and to perform work in areas where permissible equipment is not required, must comply with the following:
(1) The diesel engine powering the electrical generator must be approved under 30 CFR part 7, subpart E.
(2) A grounding resistor rated for the phase-to-phase voltage of the system must be provided to limit the ground-fault current to not more than 0.5 amperes. The grounding resistor(s) must be located:
(i) Between the wye-connected generator neutral and the generator frame; (see Figure I in Appendix A to subpart J of this part) or
(ii) Between the wye-connected generator neutral and the generator frame and between the wye-connected transformer secondary and the transformer frame when an isolation transformer(s) is used and the generator is supplying power to the other equipment; (see Figure II in Appendix A to subpart J of this part) or
(iii) Between the wye-connected generator neutral and the generator frame when an auto-transformer is used. (see Figure III in Appendix A to subpart J of this part)
(3) Each three-phase output circuit of the generator must be equipped with a sensitive ground fault relay. The protective relay must be set to cause the circuit interrupting device that supplies power to the primary windings of each transformer to trip and shut down the diesel engine when a phase-to-frame fault of not more than 90 milliamperes occurs.
(4) Each three-phase output circuit that supplies power to equipment must be equipped with an instantaneous sensitive ground-fault relay that will cause its respective circuit interrupting device(s) to trip and cause shutdown of the diesel engine when a phase-to-frame fault occurs. The grounded-phase protection must be set at not more than 90 milliamps. Current transformers used for the ground-fault protection must be single window-type and must be installed to encircle all three phase conductors. Equipment safety grounding conductors must not pass through or be connected in series with ground-fault current transformers.
(5) Each three-phase circuit interrupting device must be provided with a means to provide short-circuit, overcurrent, grounded-phase, undervoltage, and ground wire monitoring protection. The instantaneous only trip unit for the circuit interrupting device(s) in use must be adjusted to trip at not more than 75 percent of the minimum available short circuit current at the point where the portable cable enters the equipment or the maximum allowable instantaneous settings specified in § 75.601-1, whichever is less.
(6) The equipment portable cable length(s) must not exceed the length(s) specified in 30 CFR part 18, appendix I, table 9, Specifications for Cables Longer than 500 Feet.
(7) Permanent label(s) listing the maximum circuit interrupting device setting(s) and maximum portable cable length(s) must be installed on each instantaneous trip unit or be maintained near each three-phase circuit interrupting device. The permanent label(s) must be maintained legibly.
(8) The circuit interrupting device that supplies three-phase power circuit(s) to the equipment being powered must be limited to the use of only one circuit interrupting device at a time when equipment is being moved in, out, and around the mine.
(9) The grounding system must include an MSHA-accepted ground wire monitor system that satisfies the requirements of § 75.902; or have a No. 1/0 or larger external grounding conductor to bond and ground the frames of all equipment to the frame of the generator.
(10) All trailing cables extending from the generator to equipment must comply with § 75.907.
(11) A strain relief device must be provided on each end of the trailing cables that extends between the generator and the piece of equipment being powered.
(12) Prior to moving each piece of equipment or performing work, a functional test of each ground fault and ground wire monitor system must be performed by a qualified electrician who meets the requirements of § 75.153. The ground-fault circuit must be tested without subjecting the circuit to an actual grounded phase condition. A record of each test must be maintained and made available to authorized representatives of the Secretary and to the miners in such mine.
§ 75.902   Low- and medium-voltage ground check monitor circuits.
On or before September 30, 1970, low- and medium-voltage resistance grounded systems shall include a fail-safe ground check circuit to monitor continuously the grounding circuit to assure continuity which ground check circuit shall cause the circuit breaker to open when either the ground or pilot check wire is broken, or other no less effective device approved by the Secretary or his authorized representative to assure such continuity, except that an extension of time, not in excess of 12 months, may be permitted by the Secretary on a mine-by-mine basis if he determines that such equipment is not available. Cable couplers shall be constructed so that the ground check continuity conductor shall be broken first and the ground conductors shall be broken last when the coupler is being uncoupled.
§ 75.902-1   Maximum voltage ground check circuits.
The maximum voltage used for such ground check circuits shall not exceed 40 volts.
§ 75.902-2   Approved ground check systems not employing pilot check wires.
Ground check systems not employing pilot check wires will be approved only if it is determined that the system includes a fail safe design causing the circuit breaker to open when ground continuity is broken.
§ 75.902-4   Attachment of ground conductors and ground check wires to equipment frames; use of separate connections.
In grounding equipment frames of all stationary, portable or mobile equipment receiving power from resistance grounded systems separate connections shall be used when practicable.
§ 75.903   Disconnecting devices.
Disconnecting devices shall be installed in conjunction with the circuit breaker to provide visual evidence that the power is disconnected.
§ 75.904   Identification of circuit breakers.
Circuit breakers shall be marked for identification.
§ 75.905   Connection of single-phase loads.
Single-phase loads shall be connected phase-to-phase.
§ 75.906   Trailing cables for mobile equipment, ground wires, and ground check wires.
Trailing cables for mobile equipment shall contain one or more ground conductors having a cross-sectional area of not less than one-half the power conductor, and, on September 30, 1970, an insulated conductor for the ground continuity check circuit or other no less effective device approved by the Secretary or his authorized representative to assure such continuity, except that an extension of time, not in excess of 12 months may be permitted by the Secretary on a mine-by-mine basis if he determines that such equipment is not available. Splices made in the cables shall provide continuity of all components.
§ 75.907   Design of trailing cables for medium-voltage circuits.
Trailing cables for medium-voltage circuits shall include grounding conductors, a ground check conductor, and grounded metallic shields around each power conductor or a ground metallic shield over the assembly, except that on equipment employing cable reels, cables without shields may be used if the insulation is rated 2,000 volts or more.
§ 75.1000   Cutout switches.
Trolley wires and trolley feeder wires, shall be provided with cutout switches at intervals of not more than 2,000 feet and near the beginning of all branch lines.
§ 75.1001   Overcurrent protection.
Trolley wires and trolley feeder wires shall be provided with overcurrent protection.
§ 75.1001-1   Devices for overcurrent protection; testing and calibration requirements; records.
(a) Automatic circuit interrupting devices that will deenergize the affected circuit upon occurrence of a short circuit at any point in the system will meet the requirements of § 75.1001.
(b) Automatic circuit interrupting devices described in paragraph (a) of this section shall be tested and calibrated at intervals not to exceed six months. Testing of such devices shall include passing the necessary amount of electric current through the device to cause activation. Calibration of such devices shall include adjustment of all associated relays to ±15 percent of the indicated value. An authorized representative of the Secretary may require additional testing or calibration of these devices.
(c) A record of the tests and calibrations required by paragraph (b) of this section shall be kept, and shall be made available, upon request, to an authorized representative of the Secretary.
§ 75.1002   Installation of electric equipment and conductors; permissibility.
(a) Electric equipment must be permissible and maintained in a permissible condition when such equipment is located within 150 feet of pillar workings or longwall faces.
(b) Electric conductors and cables installed in or in by the last open crosscut or within 150 feet of pillar workings or longwall faces must be—
(1) Shielded high-voltage cables supplying power to permissible longwall equipment;
(2) Interconnecting conductors and cables of permissible longwall equipment;
(3) Conductors and cables of intrinsically safe circuits; and
(4) Cables and conductors supplying power to low- and medium-voltage permissible equipment.
(5) Shielded high-voltage cables supplying power to permissible continuous mining machines.
§ 75.1003   Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley wires and trolley feeder wires.
Trolley wires, trolley feeder wires, and bare signal wires shall be insulated adequately where they pass through doors and stoppings, and where they cross other power wires and cables. Trolley wires and trolley feeder wires shall be guarded adequately:
(a) At all points where men are required to work or pass regularly under the wires;
(b) On both sides of all doors and stoppings; and
(c) At man-trip stations.
§ 75.1003-1   Other requirements for guarding of trolley wires and trolley feeder wires.
Adequate precaution shall be taken to insure that equipment being moved along haulageways will not come in contact with trolley wires or trolley feeder wires.
§ 75.1003-2   Requirements for movement of off-track mining equipment in areas of active workings where energized trolley wires or trolley feeder wires are present; pre-movement requirements; certified and qualified persons.
(a) Prior to moving or transporting any unit of off-track mining equipment in areas of the active workings where energized trolley wires or trolley feeder wires are present:
(1) The unit of equipment shall be examined by a certified person to ensure that coal dust, float coal dust, loose coal oil, grease, and other combustible materials have been cleaned up and have not been permitted to accumulate on such unit of equipment; and,
(2) A qualified person, as specified in § 75.153 of this part, shall examine the trolley wires, trolley feeder wires, and the associated automatic circuit interrupting devices provided for short circuit protection to ensure that proper short circuit protection exists.
(b) A record shall be kept of the examinations required by paragraph (a) of this section, and shall be made available, upon request, to an authorized representative of the Secretary.
(c) Off-track mining equipment shall be moved or transported in areas of the active workings where energized trolley wires or trolley feeder wires are present only under the direct supervision of a certified person who shall be physically present at all times during moving or transporting operations.
(d) The frames of off-track mining equipment being moved or transported, in accordance with this section, shall be covered on the top and on the trolley wire side with fire-resistant material which has met the applicable requirements of Part 18 of Subchapter D of this chapter (Bureau of Mines Schedule 2G).
(e) Electrical contact shall be maintained between the mine track and the frames of off-track mining equipment being moved in-track and trolley entries, except that rubber-tired equipment need not be grounded to a transporting vehicle if no metal part of such rubber-tired equipment can come into contact with the transporting vehicle.
(f) A minimum vertical clearance of 12 inches shall be maintained between the farthest projection of the unit of equipment which is being moved and the energized trolley wires or trolley feeder wires at all times during the movement or transportation of such equipment; provided, however, that if the height of the coal seam does not permit 12 inches of vertical clearance to be so maintained, the following additional precautions shall be taken:
(1)(i) Except as provided in paragraph (f)(1)(ii) of this section electric power shall be supplied to the trolley wires or trolley feeder wires only from outby the unit of equipment being moved or transported.
(ii) Where direct current electric power is used and such electric power can be supplied only from inby the equipment being moved or transported, power may be supplied from inby such equipment provided a miner with the means to cut off the power, and in direct communication with persons actually engaged in the moving or transporting operation, is stationed outby the equipment being moved.
(2) The settings of automatic circuit interrupting devices used to provide short circuit protection for the trolley circuit shall be reduced to not more than one-half of the maximum current that could flow if the equipment being moved or transported were to come into contact with the trolley wire or trolley feeder wire;
(3) At all times the unit of equipment is being moved or transported, a miner shall be stationed at the first automatic circuit breaker outby the equipment being moved and such miner shall be: (i) In direct communication with persons actually engaged in the moving or transporting operation, and (ii) capable of communicating with the responsible person on the surface required to be on duty in accordance with § 75.1600-1 of this part;
(4) Where trolley phones are utilized to satisfy the requirements of paragraph (f)(3) of this section, telephones or other equivalent two-way communication devices that can readily be connected with the mine communication system shall be carried by the miner stationed at the first automatic circuit breaker outby the equipment being moved and by a miner actually engaged in the moving or transporting operation; and,
(5) No person shall be permitted to be inby the unit of equipment being moved or transported, in the ventilating current of air that is passing over such equipment, except those persons directly engaged in moving such equipment.
(g) The provisions of paragraphs (a) through (f) of this section shall not apply to units of mining equipment that are transported in mine cars, provided that no part of the equipment extends above or over the sides of the mine car.
§ 75.1100   Requirements.
Each coal mine shall be provided with suitable firefighting equipment adapted for the size and conditions of the mine. The Secretary shall establish minimum requirements of the type, quality, and quantity of such equipment.
§ 75.1100-1   Type and quality of firefighting equipment.
Firefighting equipment required under this subpart shall meet the following minimum requirements:
(a) Waterlines: Waterlines shall be capable of delivering 50 gallons of water a minute at a nozzle pressure of 50 pounds per square inch.
(b) Portable water cars: A portable water car shall be of at least 1,000 gallons capacity (500 gallons capacity for anthracite mines) and shall have at least 300 feet of fire hose with nozzles. A portable water car shall be capable of providing a flow through the hose of 50 gallons of water per minute at a nozzle pressure of 50 pounds per square inch.
(c) A portable chemical car shall carry enough chemicals to provide a fire extinguishing capacity equivalent to that of a portable water car.
(d) Portable foam-generating machines or devices: A portable foam-generating machine or device shall have facilities and equipment for supplying the machine with 30 gallons of water per minute at 30 pounds per square inch for a period of 35 minutes.
(e) Portable fire extinguisher: A portable fire extinguisher shall be either (1) a multipurpose dry chemical type containing a nominal weight of 5 pounds of dry powder and enough expellant to apply the powder or (2) a foam-producing type containing at least 2 1/2 gallons of foam-producing liquids and enough expellant to supply the foam. Only fire extinguishers approved by the Underwriters Laboratories, Inc., or Factory Mutual Research Corp., carrying appropriate labels as to type and purpose, shall be used. After March 30, 1971, all new portable fire extinguishers acquired for use in a coal mine shall have a 2A 10 BC or higher rating.
(f)(1) Except as provided in paragraph (f)(2) of this section, the fire hose shall be lined with a material having flame resistant qualities meeting requirements for hose in Bureau of Mines' Schedule 2G. The cover shall be polyester, or other material with flame-spread qualities and mildew resistance equal or superior to polyester. The bursting pressure shall be at least 4 times the water pressure at the valve to the hose inlet with the valve closed; the maximum water pressure in the hose nozzle shall not exceed 100 p.s.i.g.
(2) Fire hose installed for use in underground coal mines prior to December 30, 1970, shall be mildew-proof and have a bursting pressure at least 4 times the water pressure at the valve to the hose inlet with the valve closed, and the maximum water pressure in the hose nozzle with water flowing shall not exceed 100 p.s.i.g.
§ 75.1100-2   Quantity and location of firefighting equipment.
(a) Working sections. (1) Each working section of coal mines producing 300 tons or more per shift shall be provided with two portable fire extinguishers and 240 pounds of rock dust in bags or other suitable containers; waterlines shall extend to each section loading point and be equipped with enough fire hose to reach each working face unless the section loading point is provided with one of the following:
(i) Two portable water cars; or
(ii) Two portable chemical cars; or
(iii) One portable water car or one portable chemical car, and either ( a ) a portable foam-generating machine or ( b ) a portable high-pressure rock-dusting machine fitted with at least 250 feet of hose and supplied with at least 60 sacks of rock dust.
(2) Each working section of coal mines producing less than 300 tons of coal per shift shall be provided with the following:
(i) Two portable fire extinguishers; and
(ii) 240 pounds of rock dust in bags or other suitable containers; and
(iii) At least 500 gallons of water and at least three pails of 10-quart capacity; or a waterline with sufficient hose to reach the working places; or a portable water car of at least 500-gallons capacity; or a portable, all-purpose, dry-powder chemical car of at least 125-pounds capacity.
(3) As an alternative to paragraph (a)(2) of this section, each working section with no electrical equipment at the face of an anthracite coal mine producing less than 300 tons of coal per shift shall be provided with the following:
(i) Portable fire extinguishers containing a total capacity of at least 30 pounds of dry chemical or 15 gallons of foam and located at the entrance to the gangway at the bottom of the slope; and
(ii) Portable fire extinguishers containing a total capacity of at least 20 pounds of dry chemical or 10 gallons of foam and located within 500 feet from the working face.
(b) Belt conveyors. In all coal mines, waterlines shall be installed parallel to the entire length of belt conveyors and shall be equipped with firehose outlets with valves at 300-foot intervals along each belt conveyor and at tailpieces. At least 500 feet of firehose with fittings suitable for connection with each belt conveyor waterline system shall be stored at strategic locations along the belt conveyor. Waterlines may be installed in entries adjacent to the conveyor entry belt as long as the outlets project into the belt conveyor entry.
(c) Haulage tracks. (1) In mines producing 300 tons of coal or more per shift waterlines shall be installed parallel to all haulage tracks using mechanized equipment in the track or adjacent entry and shall extend to the loading point of each working section. Waterlines shall be equipped with outlet valves at intervals of not more than 500 feet, and 500 feet of firehose with fittings suitable for connection with such waterlines shall be provided at strategic locations. Two portable water cars, readily available, may be used in lieu of waterlines prescribed under this paragraph.
(2) In mines producing less than 300 tons of coal per shift, there shall be provided at 500-foot intervals in all main and secondary haulage roads:
(i) A tank of water of at least 55-gallon capacity with at least 3 pails of not less than 10-quart capacity; or
(ii) Not less than 240 pounds of bagged rock dust.
(d) Transportation. Each track or off-track locomotive, self-propelled man-trip car, or personnel carrier shall be equipped with one portable fire extinguisher.
(e) Electrical installations. At each electrical installation, the operator shall provide two portable fire extinguishers that have a nominal capacity of 5 pounds of dry chemical, or one extinguisher that has a nominal capacity of at least 10 pounds of dry chemical, and which have a 2-A:10-B:C or higher rating.
(f) Oil storage stations. Two portable fire extinguishers and 240 pounds of rock dust, shall be provided at each permanent underground oil storage station. One portable fire extinguisher shall be provided at each working section where 25 gallons or more of oil are stored in addition to extinguishers required under paragraph (a) of this section.
(g) Welding, cutting, soldering. One portable fire extinguisher or 240 pounds of rock dust shall be provided at locations where welding, cutting, or soldering with arc or flame is being done.
(h) Powerlines. At each wooden door through which powerlines pass there shall be one portable fire extinguisher or 240 pounds of rock dust within 25 feet of the door on the intake air side.
(i) Emergency materials. (1) At each mine producing 300 tons of coal or more per shift there shall be readily available the following materials at locations not exceeding 2 miles from each working section:
(2) At each mine producing less than 300 tons of coal per shift the above materials shall be available at the mine, provided, however, that the emergency materials for one or more mines may be stored at a central warehouse or building supply company and such supply must be the equivalent of that required for all mines involved and within 1-hour's delivery time from each mine. This exception shall not apply where the active working sections are more than 2 miles from the surface.
§ 75.1100-3   Condition and examination of firefighting equipment.
All firefighting equipment shall be maintained in a usable and operative condition. Chemical extinguishers shall be examined every 6 months and the date of the examination shall be written on a permanent tag attached to the extinguisher.
§ 75.1101   Deluge-type water sprays, foam generators; main and secondary belt-conveyor drives.
Deluge-type water sprays or foam generators automatically actuated by rise in temperature, or other no less effective means approved by the Secretary of controlling fire, shall be installed at main and secondary belt-conveyor drives.
§ 75.1101-1   Deluge-type water spray systems.
(a) Deluge-type spray systems shall consist of open nozzles attached to branch lines. The branch lines shall be connected to a waterline through a control valve operated by a fire sensor. Actuation of the control valve shall cause water to flow into the branch lines and discharge from the nozzles.
(b) Nozzles attached to the branch lines shall be full cone, corrosion resistant and provided with blow-off dust covers. The spray application rate shall not be less than 0.25 gallon per minute per square foot of the top surface of the top belt and the discharge shall be directed at both the upper and bottom surfaces of the top belt and to the upper surface of the bottom belt.
§ 75.1101-2   Installation of deluge-type sprays.
Deluge-type water spray systems shall provide protection for the belt drive and 50 feet of fire-resistant belt or 150 feet of nonfire-resistant belt adjacent to the belt drive.
§ 75.1101-3   Water requirements.
Deluge-type water spray systems shall be attached to a water supply. Water so supplied shall be free of excessive sediment and noncorrosive to the system Water pressure shall be maintained consistent with the pipe, fittings, valves, and nozzles at all times. Water systems shall include strainers with a flush-out connection and a manual shut-off valve. The water supply shall be adequate to provide flow for 10 minutes except that pressure tanks used as a source of water supply shall be of 1,000-gallon capacity for a fire-resistant belt and 3,000 gallons for a nonfire-resistant belt may be provided.
§ 75.1101-4   Branch lines.
As a part of the deluge-type water spray system, two or more branch lines of nozzles shall be installed. The maximum distance between nozzles shall not exceed 8 feet.
§ 75.1101-5   Installation of foam generator systems.
(a) Foam generator systems shall be located so as to discharge foam to the belt drive, belt takeup, electrical controls, gear reducing unit and the conveyor belt.
(b) Foam generator systems shall be equipped with a fire sensor which actuates the system, and each system shall be capable of producing and delivering the following amounts of foam within 5 minutes:
(1) At fire-resistant belt installations, an amount which will fully envelop the belt drive, belt takeup, electrical controls, gear reducing unit, and the conveyor belt over a distance of 50 feet; and,
(2) At nonfire-resistant belt installations, an amount which will fully envelop the belt drive, belt takeup electrical controls, gear reducing unit, and the conveyor belt over a distance of 150 feet.
(c) The foam generator shall be equipped with a warning device designed to stop the belt drive when a fire occurs and all such warning devices shall be capable of giving both an audible and visual signal when actuated by fire.
(d) Water, power, and chemicals required shall be adequate to maintain water or foam flow for no less than 25 minutes.
(e) Water systems shall include strainers with a flush-out connection and a manual shut-off valve.
§ 75.1101-6   Water sprinkler systems; general.
Water sprinkler systems may be installed to protect main and secondary belt-conveyor drives, however, where such systems are employed, they shall be installed and maintained in accordance with §§ 75.1101-7 through 75.1101-11.
§ 75.1101-7   Installation of water sprinkler systems; requirements.
(a) The fire-control components of each water sprinkler system shall be installed, as far as practicable in accordance with the recommendations set forth in National Fire Protection Association 1968-69 edition, Code No. 13, “Installation of Sprinkler Systems” and such systems' components shall be of a type approved by the Underwriters' Laboratories, Inc., Factory Mutual Research Corp.
(b) Each sprinkler system shall provide protection for the motor drive belt takeup, electrical controls, gear reducing unit, and the 50 feet of fire-resistant belt, or 150 feet of nonfire-resistant belt adjacent to the belt drive.
(c) The components of each water sprinkler system shall be located so as to minimize the possibility of damage by roof fall or by the moving belt and its load.
§ 75.1101-8   Water sprinkler systems; arrangement of sprinklers.
(a) At least one sprinkler shall be installed above each belt drive, belt take-up, electrical control, and gear-reducing unit, and individual sprinklers shall be installed at intervals of no more than 8 feet along all conveyor branch lines.
(b) Two or more branch lines, at least one of which shall be above the top belt and one between the top and bottom belt, shall be installed in each sprinkler system to provide a uniform discharge of water to the belt surface.
(c) The water discharge rate from the sprinkler system shall not be less than 0.25 gallon per minute per square foot of the top surface of the top belt and the discharge shall be directed at both the upper and bottom surfaces of the top belt and to the upper surface of the bottom belt. The supply of water shall be adequate to provide a constant flow of water for 10 minutes with all sprinklers functioning.
(d) Each individual sprinkler shall be activated at a temperature of not less than 150 °F. and not more than 300 °F.
(e) Water systems shall include strainers with a flush-out connection and a manual shut-off valve.
§ 75.1101-9   Back-up water system.
One fire hose outlet together with a length of hose capable of extending to the belt drive shall be provided within 300 feet of each belt drive.
§ 75.1101-10   Water sprinkler systems; fire warning devices at belt drives.
Each water sprinkler system shall be equipped with a device designed to stop the belt drive in the event of a rise in temperature and each such warning device shall be capable of giving both an audible and visual warning when a fire occurs.
§ 75.1101-11   Inspection of water sprinkler systems.
Each water sprinkler system shall be examined weekly and a functional test of the complete system shall be conducted at least once each year.
§ 75.1101-12   Equivalent dry-pipe system.
Where water sprinkler systems are installed to protect main and secondary belt conveyor drives and freezing temperatures prevail, an equivalent dry-pipe system may be installed.
§ 75.1101-13   Dry powder chemical systems; general.
Self-contained dry powder chemical systems may be installed to protect main and secondary belt conveyor drives, however, where such systems are employed, they shall be installed and maintained in accordance with the provisions of §§ 75.1101-14 through 75.1101-22.
§ 75.1101-14   Installation of dry powder chemical systems.
(a) Self-contained dry powder chemical systems shall be installed to protect each belt-drive, belt takeup, electrical-controls, gear reducing units and 50 feet of fire-resistant belt or 150 feet of non-fire-resistant belt adjacent to the belt drive.
(b) The fire-control components of each dry powder chemical system shall be a type approved by the Underwriters' Laboratories, Inc., or Factory Mutual Engineering Corp.
(c) The components of each dry powder chemical system shall be located so as to minimize the possibility of damage by roof fall or by the moving belt and its load.
§ 75.1101-15   Construction of dry powder chemical systems.
(a) Each self-contained dry powder system shall be equipped with hose or pipe lines which are no longer than necessary.
(b) Metal piping and/or hose between control valves and nozzles shall have a minimum bursting pressure of 500 p.s.i.g.
(c) Hose shall be protected by wire braid or its equivalent.
(d) Nozzles and reservoirs shall be sufficient in number to provide maximum protection to each belt, belt takeup, electrical controls, and gear reducing unit.
(e) Each belt shall be protected on the top surface of both the top and bottom belts and the bottom surface of the top belt.
§ 75.1101-16   Dry powder chemical systems; sensing and fire-suppression devices.
(a) Each self-contained dry powder chemical system shall be equipped with sensing devices which shall be designed to activate the fire-control system, sound an alarm and stop the conveyor drive motor in the event of a rise in temperature, and provision shall be made to minimize contamination of the lens of any optical sensing device installed in such system.
(b) Where sensors are operated from the same power source as the belt drive, each sensor shall be equipped with a standby power source which shall be capable of remaining operative for at least 4 hours after a power cutoff.
(c) Sensor systems shall include a warning indicator (or test circuit) which shows it is operative.
(d) Each fire-suppression system shall be equipped with a manually operated control valve which shall be independent of the sensor.
§ 75.1101-17   Sealing of dry powder chemical systems.
Each dry powder chemical system shall be adequately sealed to protect all components of the system from moisture dust, and dirt.
§ 75.1101-18   Dry powder requirements.
Each dry powder chemical system shall contain the following minimum amounts of multipurpose dry powder:
§ 75.1101-19   Nozzles; flow rate and direction.
The nozzles of each dry powder chemical system shall be capable of discharging all powder within 1 minute after actuation of the system and such nozzles shall be directed so as to minimize the effect of ventilation upon fire control.
§ 75.1101-20   Safeguards for dry powder chemical systems.
Adequate guards shall be provided along all belt conveyors in the vicinity of each dry powder chemical system to protect persons whose vision is restricted by a discharge of powder from the system. In addition, hand-rails shall be installed in such areas to provide assistance to those passing along the conveyor after a powder discharge.
§ 75.1101-21   Back-up water system.
One fire hose outlet together with a length of hose capable of extending to the belt drive shall be provided within 300 feet of each belt drive.
§ 75.1101-22   Inspection of dry powder chemical systems.
(a) Each dry powder chemical system shall be examined weekly and a functional test of the complete system shall be conducted at least once each year.
(b) Where the dry powder chemical system has been actuated, all components of the system shall be cleaned immediately by flushing all powder from pipes and hoses and all hose damaged by fire shall be replaced.
§ 75.1102   Slippage and sequence switches.
Underground belt conveyors shall be equipped with slippage and sequence switches.
§ 75.1103   Automatic fire warning devices.
On or before May 29, 1970, devices shall be installed on all such belts which will give a warning automatically when a fire occurs on or near such belt. The Secretary shall prescribe a schedule for installing fire suppression devices on belt haulageways.
§ 75.1103-1   Automatic fire sensors.
A fire sensor system shall be installed on each underground belt conveyor. Sensors so installed shall be of a type which will (a) give warning automatically when a fire occurs on or near such belt; (b) provide both audible and visual signals that permit rapid location of the fire.
§ 75.1103-2   Automatic fire sensors; approved components; installation requirements.
(a) The components of each automatic fire sensor required to be installed in accordance with the provisions of § 75.1103-1 shall be of a type and installed in a manner approved by the Secretary, or the components shall be of a type listed, approved and installed in accordance with the recommendations of a nationally recognized testing laboratory approved by the Secretary.
(b) Where applicable, and not inconsistent with these regulations, automatic fire sensors shall be installed in accordance with the recommendations set forth in National Fire Code No. 72A “Local Protective Signaling Systems” (NFPA No. 72A-1967). National Fire Code No. 72A (1967) is hereby incorporated by reference and made a part hereof. National Fire Code No. 72A is available for examination at each MSHA Coal Mine Safety and Health district office, and may be obtained from the National Fire Protection Association, 11 Tracy Drive, Avon, MA 02322; Telephone: 800-344-3555 (toll free); http://www.nfpa.org.
§ 75.1103-3   Automatic fire sensor and warning device systems; minimum requirements; general.
Automatic fire sensor and warning device systems installed in belt haulageways of underground coal mines shall be assembled from components which meet the minimum requirements set forth in §§ 75.1103-4 through 75.1103-7 unless otherwise approved by the Secretary.
§ 75.1103-4   Automatic fire sensor and warning device systems; installation; minimum requirements.
(a) Effective December 31, 2009, automatic fire sensor and warning device systems that use carbon monoxide sensors shall provide identification of fire along all belt conveyors.
(1) Carbon monoxide sensors shall be installed at the following locations:
(i) Not more than 100 feet downwind of each belt drive unit, each tailpiece transfer point, and each belt take-up. If the belt drive, tailpiece, and/or take-up for a single transfer point are installed together in the same air course, and the distance between the units is less than 100 feet, they may be monitored with one sensor downwind of the last component. If the distance between the units exceeds 100 feet, additional sensors are required downwind of each belt drive unit, each tailpiece transfer point, and each belt take-up;
(ii) Not more than 100 feet downwind of each section loading point;
(iii) Along the belt entry so that the spacing between sensors does not exceed 1,000 feet. Where air velocities are less than 50 feet per minute, spacing must not exceed 350 feet; and
(iv) The mine operator shall indicate the locations of all carbon monoxide sensors on the mine maps required by §§ 75.1200 and 75.1505 of this part.
(2) Where used, sensors responding to radiation, smoke, gases, or other indications of fire, shall be spaced at regular intervals to provide protection equivalent to carbon monoxide sensors, and installed within the time specified in paragraph (a)(3) of this section.
(3) When the distance from the tailpiece at loading points to the first outby sensor reaches the spacing requirements in § 75.1103-4(a)(1)(iii), an additional sensor shall be installed and put in operation within 24 production shift hours. When sensors of the kind described in paragraph (a)(2) of this section are used, they shall be installed and put in operation within 24 production shift hours after the equivalent distance which has been established for the sensor from the tailpiece at loading points to the first outby sensor is first reached.
(b) Automatic fire sensor and warning device systems shall be installed so as to minimize the possibility of damage from roof falls and the moving belt and its load. Sensors must be installed near the center in the upper third of the entry, in a manner that does not expose personnel working on the system to unsafe conditions. Sensors must not be located in abnormally high areas or in other locations where air flow patterns do not permit products of combustion to be carried to the sensors.
(c) Infrared, ultraviolet, and other sensors whose effectiveness is impaired by contamination shall be protected from dust, dirt, and moisture.
(d) The voltage of automatic fire sensor and warning device systems shall not exceed 120 volts.
(e) Except when power must be cut off in the mine under the provisions of § 75.313, automatic fire sensor and warning device systems shall be capable of giving warning of fire for a minimum of 4 hours after the source of power to the belt is removed unless the belt haulageway is examined for hot rollers and fire as provided in paragraph (e) (1) or (2) of this section.
(1) When an unplanned removal of power from the belt occurs an examination for hot rollers and fire in the operating belts of a conveyor system shall be completed within 2 hours after the belt has stopped.
(2) When a preplanned removal of power from the belt occurs an examination for hot rollers and fire on the operating belts of a conveyor system may commence not more than 30 minutes before the belts are stopped and shall be completed within 2 hours after the examination is commenced, or the examination shall be commenced when the belts are stopped and completed within 2 hours after the belts are stopped.
§ 75.1103-5   Automatic fire warning devices; actions and response.
(a) When the carbon monoxide level reaches 10 parts per million above the established ambient level at any sensor location, automatic fire sensor and warning device systems shall provide an effective warning signal at the following locations:
(1) At working sections and other work locations where miners may be endangered from a fire in the belt entry.
(2) At a manned surface location where personnel have an assigned post of duty. The manned surface location must have:
(i) A telephone or equivalent communication with all miners who may be endangered and
(ii) A map or schematic that shows the locations of sensors, and the intended air flow direction at these locations. This map or schematic must be updated within 24 hours of any change in this information.
(3) The automatic fire sensor and warning device system shall be monitored for a period of 4 hours after the belt is stopped, unless an examination for hot rollers and fire is made as prescribed in § 75.1103-4(e).
(b) The fire sensor and warning device system shall include a means for rapid evaluation of electrical short and open circuits, ground faults, pneumatic leaks, or other defect detrimental to its proper operational condition.
(c) Automatic fire sensor and warning devices shall include a manual reset feature.
(d) When a malfunction or warning signal is received at the manned surface location, the sensors that are activated must be identified and appropriate personnel immediately notified.
(e) Upon notification of a malfunction or warning signal, appropriate personnel must immediately initiate an investigation to determine the cause of the malfunction or warning signal and take the required actions set forth in paragraph (f) of this section.
(f) If any sensor indicates a warning, the following actions must be taken unless the mine operator determines that the signal does not present a hazard to miners:
(1) Appropriate personnel must notify miners in affected working sections, in affected areas where mechanized mining equipment is being installed or removed, and at other locations specified in the approved mine emergency evacuation and firefighting program of instruction; and
(2) All miners in the affected areas, unless assigned emergency response duties, must be immediately withdrawn to a safe location identified in the mine emergency evacuation and firefighting program of instruction.
(g) If the warning signal will be activated during calibration of sensors, personnel manning the surface location must be notified prior to and upon completion of calibration. Affected working sections, areas where mechanized mining equipment is being installed or removed, or other areas designated in the approved emergency evacuation and firefighting program of instruction must be notified at the beginning and completion of calibration.
(h) If any fire detection component becomes inoperative, immediate action must be taken to repair the component. While repairs are being made, operation of the belt may continue if the following requirements are met:
(1) If one sensor becomes inoperative, a trained person must continuously monitor for carbon monoxide at the inoperative sensor;
(2) If two or more adjacent sensors become inoperative, trained persons must patrol and continuously monitor the affected areas for carbon monoxide so that they will be traveled each hour in their entirety. Alternatively, a trained person must be stationed at each inoperative sensor to monitor for carbon monoxide;
(3) If the complete fire detection system becomes inoperative, trained persons must patrol and continuously monitor the affected areas for carbon monoxide so that they will be traveled each hour in their entirety;
(4) Trained persons who conduct monitoring under this section must have two-way voice communication capability, at intervals not to exceed 2,000 feet, and must report carbon monoxide concentrations to the surface at intervals not to exceed one hour;
(5) Trained persons who conduct monitoring under this section must immediately report to the surface any concentration of carbon monoxide that reaches 10 parts per million above the established ambient level, unless the mine operator knows that the source of the carbon monoxide does not present a hazard to miners; and
(6) Handheld detectors used to monitor the belt entry under this section must have a detection level equivalent to that of the system's carbon monoxide sensors.
§ 75.1103-6   Automatic fire sensors; actuation of fire suppression systems.
Point-type heat sensors or automatic fire sensor and warning device systems may be used to actuate deluge-type water systems, foam generator systems, multipurpose dry-powder systems, or other equivalent automatic fire suppression systems.
§ 75.1103-7   Electrical components; permissibility requirements.
The electrical components of each automatic fire sensor and warning device system shall:
(a) Remain functional when the power circuits are deenergized as required by § 75.706; and
(b) Be provided with protection against ignition of methane or coal dust when the electrical power is deenergized as required by § 75.313, but these components shall be permissible or intrinsically safe if installed in a return airway.
§ 75.1103-8   Automatic fire sensor and warning device systems; examination and test requirements.
(a) Automatic fire sensor and warning device systems shall be examined at least once each shift when belts are operated as part of a production shift. A functional test of the warning signals shall be made at least once every seven days. Examination and maintenance of such systems shall be by a qualified person.
(b) A record of the functional test conducted in accordance with paragraph (a) of this section shall be maintained by the operator and kept for a period of one year.
(c) Sensors shall be calibrated in accordance with the manufacturer's calibration instructions at intervals not to exceed 31 days. A record of the sensor calibrations shall be maintained by the operator and kept for a period of one year.
§ 75.1103-9   Minimum requirements; fire suppression materials and location; maintenance of entries and crosscuts; access doors; communications; fire crews; high-expansion foam devices.
(a) The following materials shall be stored within 300 feet of each belt drive or at a location where the material can be moved to the belt drive within 5 minutes, except that when the ventilating current in the belt haulageway travels in the direction of the normal movement of coal on the belt, the materials shall be stored within 300 feet of the belt tailpiece or at a location where the materials can be moved to the belt tailpiece within 5 minutes.
(1) 500 feet of fire hose, except that if the belt flight is less than 500 feet in length the fire hose may be equal to the length of the belt flight. A high expansion foam device may be substituted for 300 feet of the 500 feet of the fire hose. Where used, such foam generators shall produce foam sufficient to fill 100 feet of the belt haulageway in not more than 5 minutes. Sufficient power cable and water hose shall be provided so that the foam generator can be installed at any crosscut along the belt by which the generator is located. A 1-hour supply of foam producing chemicals and tools and hardware required for its operation shall be stored at the foam generator.
(2) Tools to open a stopping between the belt entry and the adjacent intake entry; and
(3) 240 pounds of bagged rock dust.
(b) The entry containing the main waterline and the crosscuts containing water outlets between such entry and the belt haulageway (if the main waterline is in an adjacent entry) shall be maintained accessible and in safe condition for travel and firefighting activities. Each stopping in such crosscuts or adjacent crosscuts shall have an access door.
(c) Suitable communication lines extending to the surface shall be provided in the belt haulageway or adjacent entry.
(d) The fire suppression system required at the belt drive shall include the belt discharge head.
(e) A crew consisting of at least five members for each working shift shall be trained in firefighting operations. Fire drills shall be held at intervals not exceeding 6 months.
§ 75.1103-10   Fire suppression systems; additional requirements.
For each conveyor belt flight exceeding 2,000 feet in length, where the average air velocity along the belt haulage entry exceeds 100 feet per minute, an additional cache of the materials specified in § 75.1103-9(a)(1), (2), and (3) shall be provided. The additional cache may be stored at the locations specified in § 75.1103-9(a), or at some other strategic location readily accessible to the conveyor belt flight.
§ 75.1103-11   Tests of fire hydrants and fire hose; record of tests.
Each fire hydrant shall be tested by opening to insure that it is in operating condition, and each fire hose shall be tested, at intervals not exceeding 1 year. A record of these tests shall be maintained at an appropriate location.
§ 75.1104   Underground storage, lubricating oil and grease.
Underground storage places for lubricating oil and grease shall be of fireproof construction. Except for specially prepared materials approved by the Secretary, lubricating oil and grease kept in all underground areas in a coal mine shall be in fireproof, closed metal containers or other no less effective containers approved by the Secretary.
§ 75.1106   Welding, cutting, or soldering with arc or flame underground.
All welding, cutting, or soldering with arc or flame in all underground areas of a coal mine shall, whenever practicable, be conducted in fireproof enclosures. Welding, cutting, or soldering with arc or flame in other than a fireproof enclosure shall be done under the supervision of a qualified person who shall make a diligent search for fire during and after such operations and shall, immediately before and during such operations, continuously test for methane with means approved by the Secretary for detecting methane. Welding, cutting, or soldering shall not be conducted in air that contains 1.0 volume per centum or more of methane. Rock dust or suitable fire extinguishers shall be immediately available during such welding, cutting or soldering.
§ 75.1106-1   Test for methane.
Until December 31, 1970, a permissible flame safety lamp may be used to make tests for methane required by the regulations in this part. On and after December 31, 1970 a methane detector approved by the Secretary shall be used for such tests and a permissible flame safety lamp may be used as a supplemental testing device. A person qualified to test for methane under § 75.151 will be a qualified person for the purpose of this section.