30 C.F.R. §§ 75.814–75.822

§75.814. Electrical protection.

30 C.F.R. § 75.814

(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.

Notes, amendments, and revision history

Source

Source: 67 FR 11001, Mar. 11, 2002, unless otherwise noted.

Authority

Authority: 30 U.S.C. 811, 813(h), 957.

Source

Source: 35 FR 17890, Nov. 20, 1970, unless otherwise noted.

§75.815. Disconnect devices.

30 C.F.R. § 75.815

(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.

Notes, amendments, and revision history

Source

Source: 67 FR 11001, Mar. 11, 2002, unless otherwise noted.

Authority

Authority: 30 U.S.C. 811, 813(h), 957.

Source

Source: 35 FR 17890, Nov. 20, 1970, unless otherwise noted.

§75.816. Guarding of cables.

30 C.F.R. § 75.816

(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.

Notes, amendments, and revision history

Source

Source: 67 FR 11001, Mar. 11, 2002, unless otherwise noted.

Authority

Authority: 30 U.S.C. 811, 813(h), 957.

Source

Source: 35 FR 17890, Nov. 20, 1970, unless otherwise noted.

§75.817. Cable handling and support systems.

30 C.F.R. § 75.817

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.

Notes, amendments, and revision history

Source

Source: 67 FR 11001, Mar. 11, 2002, unless otherwise noted.

Authority

Authority: 30 U.S.C. 811, 813(h), 957.

Source

Source: 35 FR 17890, Nov. 20, 1970, unless otherwise noted.

§75.818. Use of insulated cable handling equipment.

30 C.F.R. § 75.818

(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, 200 Constitution Avenue NW, Washington, DC 20210; 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.

Notes, amendments, and revision history

Amendments

[67 FR 11001, Mar. 11, 2002, as amended at 67 FR 38386, June 4, 2002; 71 FR 16668, Apr. 3, 2006; 80 FR 52992, Sept. 2, 2015; 91 FR 9448, Feb. 26, 2026]

Source

Source: 67 FR 11001, Mar. 11, 2002, unless otherwise noted.

Authority

Authority: 30 U.S.C. 811, 813(h), 957.

Source

Source: 35 FR 17890, Nov. 20, 1970, unless otherwise noted.

Amendments

[67 FR 11001, Mar. 11, 2002, as amended at 67 FR 38386, June 4, 2002; 71 FR 16668, Apr. 3, 2006; 80 FR 52992, Sept. 2, 2015; 91 FR 9448, Feb. 26, 2026]

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

30 C.F.R. § 75.819

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.

Notes, amendments, and revision history

Source

Source: 67 FR 11001, Mar. 11, 2002, unless otherwise noted.

Authority

Authority: 30 U.S.C. 811, 813(h), 957.

Source

Source: 35 FR 17890, Nov. 20, 1970, unless otherwise noted.

§75.820. Electrical work; troubleshooting and testing.

30 C.F.R. § 75.820

(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.

Notes, amendments, and revision history

Source

Source: 67 FR 11001, Mar. 11, 2002, unless otherwise noted.

Authority

Authority: 30 U.S.C. 811, 813(h), 957.

Source

Source: 35 FR 17890, Nov. 20, 1970, unless otherwise noted.

§75.821. Testing, examination and maintenance.

30 C.F.R. § 75.821

(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.

Notes, amendments, and revision history

Source

Source: 67 FR 11001, Mar. 11, 2002, unless otherwise noted.

Authority

Authority: 30 U.S.C. 811, 813(h), 957.

Source

Source: 35 FR 17890, Nov. 20, 1970, unless otherwise noted.

§75.822. Underground high-voltage longwall cables.

30 C.F.R. § 75.822

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.

Notes, amendments, and revision history

Source

Source: 67 FR 11001, Mar. 11, 2002, unless otherwise noted.

Authority

Authority: 30 U.S.C. 811, 813(h), 957.

Source

Source: 35 FR 17890, Nov. 20, 1970, unless otherwise noted.