Program Policy Manual - VOLUME V - Mine Safety and Health ...

MSHA PROGRAM POLICY MANUAL VOLUME V
Tapes or other materials that are used to form the outer jacket
of approved permanent splices may be used to replace damaged
areas of outer jackets of trailing cable. Outer jackets shall be
replaced in such manner so as to prevent moisture from entering
the cable.
Tar-impregnated friction tape is not adequate for insulation or
protection in the damp and wet areas of underground coal mines.
Such tape will absorb mine water, which is highly conductive,
creating a serious shock hazard to the miners.
75.518-1 Electric Equipment and Circuits; Overload and
Short Circuit Protection; Minimum Requirements
In direct-current systems that are either ungrounded or provided
with a neutral grounding point, protective elements shall be
provided for both positive and negative lines. This necessitates
the use of either a two-pole circuit breaker or a fuse in each
polarity. Fuses of the correct type and capacity are acceptable
as overload protection only for d.c. or single-phase a.c.
circuits and motors. The proper selection is based on wire size,
motor design, horsepower, and method of starting. If the
computed value is other than a common size, the next higher size
common fuse or thermal element is acceptable.
The installation of overload devices on locomotives operating on
grades exceeding 5 percent can create a hazardous condition due
to a decrease in braking power if the overcurrent protective
devices open. Noncompliance with this Section shall not be cited
for locomotives operating on grades exceeding 5 percent until
suitable automatic brakes have been designed and installed on
such locomotives and haulage cars.
75.518-2 Incandescent Lamps, Overload, and Short-Circuit
Protection
Not more than 8 feet in distance means not more than 8 feet of
ungrounded conductor.
75.519-1 Main Power Circuits; Disconnecting Switches;
Locations
This Section applies to low- and medium-voltage power circuits
entering a mine and to low-, medium-, and high-voltage power
circuits at the bottom of shafts and boreholes. The requirements
for disconnecting switches for high-voltage power circuits
entering a mine are contained in Section 75.802(c).
February 2003 (Release V-33) 66