HARRY HUGHES, Governor

1385

switch or circuit breaker shall be installed so it is
accessible readily and can be operated without danger of
contact with moving or live parts.

(b)  Disconnecting switches shall be installed in each
main power circuit at the bottom of the shaft, bore hole, or
any other place where a main power circuit enters the mine.
Underground electric equipment and circuits shall be
provided with switches or other controls of safe design and
construction. They shall be installed in a safe manner.

(c)  A power circuit shall be protected against short
circuit or excessive overload. Wire or other conducting
material may not be used as a substitute for a properly
designed fuse. If a circuit breaker is used it shall be
maintained in a proper operating condition. A dry wooden
platform, rubber mat, or other electrically nonconductive
material shall be kept in place at each switchboard,
power-control switch, and stationary machinery where shock
hazards exist.]

[7-438.

(a)  Each signal wire shall be supported on insulators
and insulated properly where it crosses any power line.

(b)  Bare signal wire readily accessible to personal
contact shall not carry more than 30 volts. This does not
apply to a block-signal system.]

[7-439.

(a)  Any electric face equipment taken into a gassy
mine shall be permissible equipment approved by the United
States Bureau of Mines, except that an explosion-tested
cable-reel locomotive and a shuttle car may be used.

(b)  Power connections shall be made in intake air or a
permissible junction or distribution box shall be used to
make every multiple-power connection in any place where a
dangerous quantity of methane may be present, or enter the
air current.

(c)  Permissible equipment shall be maintained in a
good state of repair and in permissible condition.
Explosion-tested equipment shall be maintained in a good
state of repair and in explosion-tested condition.

(d)  No electrically driven equipment may be taken into
or operated in a working place where one percent or more
methane can be detected at any point riot less than 12 inches
from the roof, face, or rib. In any face working of a gassy
mine, inspection for methane shall be made before electric
equipment is taken into or operated in the face region.
Frequent tests shall be made for methane while the equipment
is operated in the face region.