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

MSHA PROGRAM POLICY MANUAL VOLUME V
testing and troubleshooting operation, a qualified person, as
defined in Section 77.103, must be present at all times to
observe, instruct, and aid the trainee.
"Suitably tagged" means that a sign with wording such as
"Danger - Hands Off - Do Not Close - Miners Working on Line,"
shall be attached to the opened disconnecting device. The tag
should bear the name of the workman who installed it.
Keys to locks used to lock out switches should be kept by the
person working on the circuit or equipment.
77.502 Electric Equipment; Examination, Testing and
Maintenance
For purposes of this Section, "electric equipment" shall
include all control circuits; control switches or devices;
circuit breakers; fuses; conduits; wiring; motors;
transformers; lighting equipment; hand-held tools such as
drills, wrenches, and saws; etc. The tests, examinations, and
proper maintenance required by this Section shall include all
items mentioned above and all other such equipment at the mine.
77.503 Electric Conductors
Section 77.503 requires that, "electric conductors shall be
sufficient in size and have adequate current carrying capacity
and be of such construction that a rise in temperature
resulting from normal operation will not damage the insulating
materials." Section 77.503-1 outlines the term "sufficient"
and states that electric conductors must "meet the minimum
current carrying capacity provided for in the National Electric
Code, 1968" (emphasis added). While Section 77.503 states
general ampacity and conductor size requirements, Section
77.503-1 incorporates the specific minimum requirements of
standards promulgated by consensus standards organizations.
Since publication of the 1968 NEC, technological advances in
power cable manufacture have been made. Insulated conductors
having better grades of insulation and temperature ratings have
been developed which far exceed the capabilities of conductors
addressed by the 1968 NEC. Therefore, ampacity tables for
insulated conductors other than trailing cables used on the
surface and manufactured in accordance with minimum NEC
standards, or which meet the more general safety test of
Section 77.503 are acceptable.
For example, conductors manufactured in accordance with the
Insulated Cable Engineers Association (ICEA) standards, which
conform to the ICEA ampacity tables or other nationally recognized
standards would be acceptable as meeting the requirements of
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