KRS § 352.220 — KY Code / Title XXVIII / Chapter 352 / Section 352.220
352.220 Electricity in mines and surface installations
Status: in_force

352.220 Electricity in mines and surface installations.

For purposes of this section, "approved" means that a device, apparatus, equipment,

machinery, or practice employed in the mining of coal has been approved by the

commissioner of the Department for Natural Resources or accepted by a nationally or

federally recognized testing laboratory or the Department of Labor Mine Safety and

Health Administration; "suitable" means a design, material, or installation that meets the

requirements of its intended use or that is accepted by a nationally or federally recognized

testing laboratory or the Department of Labor Mine Safety and Health Administration.

(1) The following shall apply to underground installations:

(a) Nonconductive or insulated materials shall be used when trailing cables or

high voltage feeder cables are suspended;

(b) Suitable circuit-interrupting devices shall be provided for all power circuits

and equipment at the mine;

(c) All power wires and cables shall be properly insulated and protected by proper

installation or guarding;

(d) Ground wires for circuits shall have a total cross-sectional area of not less

than one-half (1/2) the power conductor;

(e) Extra length or long trailing cables shall be spread out in long open loops or in

a figure-eight configuration on a clean, well rock-dusted floor where the cable

can be protected against mechanical injury, but cables suspended in long open

loops shall be acceptable;

(f) One (1) temporary splice may be made in any trailing cable. No temporary

splice shall be made in a trailing cable within twenty-five (25) feet of the

machine except cable reel equipment. Splices in trailing cables shall be made

in a workmanlike manner and shall be mechanically strong and well insulated.

Splices made in cables shall provide continuity of all components;

(g) 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;

(h) The frames of hand-held electrically driven tools shall be properly grounded

or double-insulated by design. The frames of all pumps shall be properly

grounded. Hand-held tools and all pumps shall be properly protected by

suitable fuses, circuit breakers, or other no less effective devices to provide

the minimum overload and shortcircuit protection required by the department;

(i) 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 under or pass under them unless they are six and one-half (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

other circuits. Underground high-voltage cables used in resistance grounded

systems shall be equipped with metallic shields around each power conductor,

with one (1) or more ground conductors having a total cross-sectional area of

not less than one-half (1/2) the power conductor, and with an insulated

internal conductor not smaller than No. 10 (AWG) or an insulated external

conductor not smaller than No. 8 (AWG) for the ground continuity check

circuit. All cables shall be suitable for the current and voltage and shall be

properly maintained;

(j) Power circuits shall have suitable disconnecting devices and short-circuit

protective devices at or near the supply end of the circuit. Suitable

disconnecting devices shall be provided at the beginning of all branch circuits;

(k) Underground transformer stations, battery charging stations, substations,

rectifiers, and water pumps shall be housed in noncombustible structures or

areas or be equipped with a suitable fire-suppression system.

1. When a noncombustible structure or area is used, these installations

shall be:

a. Ventilated with intake air that is coursed into a return air course or

to the surface and that is not used to ventilate working places; or

b. Ventilated with intake air that is monitored for carbon monoxide

or smoke by an atmospheric monitoring system (AMS) installed

and operated in a suitable manner. Monitoring of intake air

ventilating battery charging stations shall be done with sensors not

affected by hydrogen; or

c. Ventilated with intake air and equipped with sensors to monitor for

heat, carbon monoxide, or smoke.

2. The sensors used for monitoring shall de-energize power to the

installation, activate a visual and audible alarm located outside of and on

the intake side of the enclosure, and activate doors that will

automatically close when any of the following occurs:

a. The temperature in noncombustible structure reaches one hundred

sixty-five (165) degrees Fahrenheit;

b. The carbon monoxide concentration reaches ten (10) parts per

million above the ambient level for the area; or

c. The optical density of smoke reaches 0.022 per meter.

3. At least every thirty (30) days, sensors installed to monitor for carbon

monoxide shall be calibrated with a known concentration of carbon

monoxide and air sufficient to activate the closing door, or each smoke

sensor shall be tested to determine that it functions correctly.

4. When a fire suppression system is used, the installation shall be:

a. Ventilated with intake air that is coursed into a return air course or

to the surface and that is not used to ventilate working places; or

b. Ventilated with intake air that is monitored for carbon monoxide

or smoke by an atmospheric monitoring system installed and

operated in a suitable manner.

5. All monitoring systems used to monitor intake air ventilating battery

charging stations under subparagraphs 1. and 4. of this paragraph shall

be done with sensors not affected by hydrogen.

6. This paragraph shall not apply to:

a. Rectifiers and power centers with transformers that either are dry-

type or contain nonflammable liquid, if they are located at or near

the section and are moved as the working section advances or

retreats;

b. Submersible pumps;

c. Permissible pumps, and associated permissible switchgear;

d. Pumps located on or near the section that are moved as the

working section advances or retreats; or

e. Small portable pumps. Underground stations containing

transformers or circuit breakers filled with flammable oil shall be

provided with door sills or their equivalent, which will confine the

oil if leakage or rupture occurs, and shall be of fireproof

construction. Underground transformers purchased after June 16,

1972, shall be air cooled or cooled with nonflammable liquid or

inert gas. Portable power centers, portable transformers, and

distribution centers which are essentially fireproof are not required

to be placed on separate splits of air but shall be stationed in well

ventilated places outby the last open crosscuts;

(l) Electrically powered locomotives shall be provided with suitable electrical

protective devices;

(m) Suitable firefighting equipment shall be located at strategic points along the

belt conveyor, and proper fire extinguishers shall be provided at the transfer

points. The commissioner may prescribe any other safety measures for the

prevention and combating of mine fires as they pertain to conveyor belts. Only

approved flame resistant belting shall be taken into and used inside any mine,

and all underground belt conveyors shall be provided with slippage and

sequence switches and with start and stop controls at intervals not to exceed

one thousand (1,000) feet. The controls shall be properly installed and

positioned so as to be readily accessible;

(n) Communication wires and cables shall be adequately insulated and protected

by proper installation or guarding;

(o) Telephone wires shall be provided with lightening arresters where the wires

enter the mine and at the buildings on the surface;

(p) Insulating mats shall be placed in front of disconnecting devices and all

electrical installations where required;

(q) Ground wires in trailing cables shall be tested weekly for open circuit and

high resistance;

(r) Power circuits in tipples, buildings, cleaning plants, etc., and all underground

electrical circuits shall be deenergized when not in use over a long period;

(s) All underground power circuits and electrical equipment shall be de-energized

before work is done on the circuits and equipment except when necessary for

troubleshooting or testing. When electrical work or major mechanical work is

performed, a suitable disconnect providing visible evidence that the power is

disconnected shall be locked open and a tag shall be posted by the individuals

performing the work. Locks and tags shall be removed only by the persons

who installed them, or if those persons are unavailable, by a person authorized

by the operator. Repairs or maintenance shall not be performed on machinery

until the power is off and the machinery is blocked against motion, except

where machinery motion is necessary to make adjustment;

(t) Where electric circuits cross over or pass under belt conveyors the wiring

shall be suitably protected; and

(u) Switch boxes, contactors, controllers, and all other similar devices shall be

kept free of significant accumulations of combustible dust.

(2) The following shall apply to trolley wires and trolley feeder wires:

(a) On all haulage roads, landings, and partings where persons are required to

regularly work or pass under bare power wires placed less than six and one-

half (6-1/2) feet above the top of the rail, suitable protection shall be provided.

This protection shall consist of channeling the roof, placing boards along the

wires and extending below them, or the use of some other approved device

that affords protection;

(b) All machine feed conductors shall be placed on suitable insulators which shall

be so placed as to prevent the conductors coming in contact with combustible

or conductive materials;

(c) When the machine or feed wires are carried in the same entry as the trolley

wire, they shall be placed on the same side as the trolley wire, between the

trolley wire and rib, and shall be protected from contact therewith. Positive

feed wires crossing places where persons are required to travel shall be safely

guarded or protected against persons coming in contact therewith, as required

by paragraph (a) of this subsection;

(d) All trolley and positive feed wires shall be placed on opposite sides of track

from refuge holes or necks of rooms when so ordered by the department, but

wires, when protected as required by paragraph (a) of this subsection, may be

placed across the necks of rooms. Switches or circuit breakers shall be

provided to control the current at the mine and all important sections in the

mine;

(e) Where track is used for the return circuit, at least one (1) side shall be bonded

to the full length of the trolley wire installation. Cross-bonds shall be installed

not to exceed two hundred (200) foot intervals along the track; and

(f) All mine locomotives shall be fused or otherwise protected at the switch or at

the nip.

(3) The following shall apply to surface installations:

(a) High-voltage lines shall be at least twenty (20) feet above the ground where

there is a possibility of contact by traffic passing underneath;

(b) Electrical circuits, wires, and cables shall be supported on insulators except

when cables, which are of a design that can be safely used without insulators,

are used;

(c) Lightning arresters shall be installed on all ungrounded, exposed power

conductors and telephone wires entering a mine, regardless of voltage.

Overload protection and disconnect switches of suitable sizes and ratings

approved by the department shall also be provided, except that they shall not

be required of telephone wires;

(d) Every metallic building in which electricity is used or connected with any

circuit shall be effectively grounded;

(e) All transformer tanks shall be effectively grounded;

(f) Switch boxes, contactors, controllers, and all other similar devices shall be

kept free of significant accumulations of combustible dust that create a fire

hazard;

(g) Surface transformer stations shall be housed or fenced in when lower than

fifteen (15) feet above the earth, and the fences shall be a minimum of six (6)

feet in height; and

(h) All surface power circuits and electrical equipment shall be de-energized

before work is done on the circuits and equipment except when necessary for

troubleshooting or testing. When electrical work or major mechanical work is

performed, a suitable disconnect providing visible evidence that the power is

disconnected shall be locked open and a tag shall be posted by the individuals

performing the work. Locks and tags shall be removed only by persons who

installed them or, if those persons are unavailable, by a person authorized by

the operator. Repairs or maintenance shall not be performed on machinery

until the power is off and the machinery is blocked against motion, except

where machinery motion is necessary to make adjustments. When disconnects

for stationary low and medium voltage equipment that do not provide visual

evidence that the power is disconnected are used, an adequately rated voltage

detector shall be used to test each phase conductor or circuit part to verify they

are de-energized before any work is performed. When practical, confirmation

that the voltage detector is operating satisfactorily shall be made before each

test.

(4) (a) Notwithstanding any provisions of subsection (1), (2), or (3) of this section,

the department may authorize the construction, maintenance, operation, or

conducting of any activity regulated by this section, to be constructed,

maintained, operated, or conducted in a different manner than specified in any

provision of subsection (1), (2), or (3) of this section, when scientific or

engineering information is made available to the department substantially

indicating that the different manner would afford equal or greater protection

and safety than the manner required in subsection (1), (2), or (3) of this

section; and

(b) The department may prescribe administrative regulations with respect to the

aboveground or underground installations in connection with any mine

operation when information is made available indicating that regulation is

reasonably necessary to prevent injury to, or loss of, life and property.

(5) All electrical work shall be performed by a certified electrician, or an electrical

trainee under the direct supervision of a certified electrician, at all underground

mines and surface mines operating draglines or highwall miners.