WM. PRESTON LANE, JR., GOVERNOR. 1063

back of the board. Switchboards shall have the entrance to
the rear guarded against entrance of unauthorized per-
sons, unless in a building that is kept locked.

, (c) Switchboards shall be well lighted for switch opera-
tions in the front and for repair and maintenance in the
rear.

Rooms housing switchboards shall be free of debris and
refuse.

Pull switches and circuit breakers, or other power con-
trols shall be mounted on slate or other suitable insulating
material.

116. Power circuits (a) High-potential power cables
(600 volts or more) carried from the surface through
shafts, boreholes, and underground passageways shall be
adequate, for the services intended, installed in a perman-
ent manner, and guarded from mechanical injury.

Power wires carrying less than 600 volts, whether bare
or insulated, except ground wires and trailing cables shall
be supported on or by well-installed insulators and shall
not touch combustible materials, roof, or ribs.

(b) Power wires shall be insulated properly when pass-
ing through doors and stoppings, and where they cross
other power circuits.

Electric cables and wires, other than signal wires and
trolley wires used for haulage, installed in haulage slopes
shall be buried not less than 12 inches below combustible
material or installed in fireproof protective conduit.

(c) Where track is used as a power conductor:

1. Both rails of main-line tracks shall be well bonded
at every joint and cross-bonded at least every 200 feet;
however, if the track circuit is paralleled with a feeder
cable, both rails of the track shall be well bonded at every
joint and cross bonds shall be installed at least every 1, 000
feet in both the track and feeder circuit.

2. At least one rail on secondary haulage roads shall be
well bonded at every joint, and cross bonds shall be in-
stalled at least every 200 feet.

3. Switches on entries shall be well bonded.

(d) Power shall be disconnected before repair work is
to be done on energized electric circuits or energized parts
of electric equipment. Employees required to make repairs
on energized bare trolley lines shall wear protective cloth-
ing, such as insulated shoes and lineman's gloves, or the
power shall be disconnected.