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

MSHA PROGRAM POLICY MANUAL VOLUME V
75.1719-2 Lighting Fixtures; Requirements
The required illumination may be provided by light fixtures which are
mounted onboard mining equipment and receive power from the
equipment, by stationary light fixtures which are mounted on the roof
or along the rib and receive power through trailing cables, or by a
combination of these two systems. Light fixtures installed on
shearers in longwall systems or continuous miners in shortwall
systems shall be considered machine-mounted light fixtures. Light
fixtures installed on roof support equipment of longwall or shortwall
mining systems shall be considered stationary light fixtures.
Stationary lighting fixtures which receive power from alternatingcurrent
systems which are not resistance grounded as provided in
paragraph (c)(2) or from direct-current systems shall be grounded in
accordance with the appropriate section of Part 75, Subpart H.
The requirements of paragraph (c)(3) apply to all machine-mounted
lighting fixtures including headlights that were furnished as
original equipment on the machine. The required grounded conductor
may be inside the supply cable to the fixture or may be an external
grounding shunt. The required grounding conductor shall be in
addition to any holes or welds used to fasten the fixture to the
machine.
When a grounding conductor inside of the supply cable is used to
ground a machine-mounted lighting fixture, the grounding conductor
shall connect the frame of the fixture to the grounded explosionproof
enclosure from which the machine-mounted lighting system
receives its power.
Paragraph (e) requires that trailing cables conducting power to
stationary lighting fixtures be protected against short circuits and
overloads. The settings of the circuit breakers providing shortcircuit
protection for such trailing cables shall not exceed the
minimum available short-circuit current at the end of the cable or
the setting specified in Section 75.601-1, whichever is lower. The
rating of the device providing overload protection shall not exceed
the capacity rating of the cable.
Since the required electrical protection for circuits and trailing
cables supplying power to stationary lighting fixtures is
specifically contained in paragraphs (c) and (e), a fail-safe groundcheck
monitor is not required for a three-phase circuit supplying
power to stationary lighting fixtures. Likewise, undervoltage
protection is not required for a three-phase circuit supplying power
to stationary lighting fixtures. The maximum length of trailing
cables conducting power to stationary lighting fixtures is not
specified; however, the requirement for short-circuit protection will
limit the length of such cable.
February 2003 (Release V-33) 155