Program Policy Manual - VOLUME V - Mine Safety and Health ...
Program Policy Manual - VOLUME V - Mine Safety and Health ...
Program Policy Manual - VOLUME V - Mine Safety and Health ...
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MSHA PROGRAM POLICY MANUAL <strong>VOLUME</strong> V<br />
the dielectric <strong>and</strong> tensile strength of the J-hook <strong>and</strong> if, in the<br />
opinion of the authorized representative of the Secretary, the Jhook<br />
is adequate for the duty imposed. The following guidelines<br />
shall be used as criteria for the acceptance of J-hooks as<br />
insulators:<br />
1. The dielectric strength of the J-hook shall not be less<br />
than eight times the voltage of the circuit.<br />
2. The tensile strength shall not be less than three times<br />
the weight the J-hook is intended to support.<br />
Insulated J-hooks that do meet the above requirements will be<br />
acceptable as insulators for permanent installations of insulated<br />
control cables <strong>and</strong> insulated control wire (either singleconductor<br />
or twisted pair) or for temporary installation (not<br />
more than 6 months) of insulated power cables.<br />
This Section does not prohibit single-conductor cables used in<br />
three-phase resistance-grounded low-voltage circuits from being<br />
installed on proper hangers <strong>and</strong> supported by a grounded messenger<br />
wire or insulated wires from being installed in grounded metal<br />
conduit.<br />
75.517 Power Wires <strong>and</strong> Cables; Insulation <strong>and</strong> Protection<br />
Any ungrounded power conductor extending from the track entry for<br />
any purpose shall be insulated. In addition, power wires <strong>and</strong><br />
cables shall be installed under well supported roof <strong>and</strong> far<br />
enough away from any moving equipment to prevent damage; however,<br />
in some locations, metal or nonmetallic conduit may be necessary<br />
for additional protection against damage. Examples of these<br />
locations include: where power wires or cables other than<br />
trolley feeder wires cross the trolley wire; where power wires or<br />
cables pass through doors or stoppings; where power wires or<br />
cables are installed along supply storage areas; where power<br />
wires or cables are installed on tight corners with insufficient<br />
clearance; or other areas where power wires or cables cannot be<br />
isolated sufficiently to afford protection.<br />
This Section also requires that damaged insulation on insulated<br />
power wires <strong>and</strong> cables (including trailing cables) <strong>and</strong> damaged<br />
jackets on power cables (including trailing cables) be repaired.<br />
The outer jacket of a cable is intended to protect the internal<br />
conductors from cuts, abrasion, moisture, etc., <strong>and</strong> must be<br />
intact for the cable to be fully protected as required by this<br />
Section.<br />
February 2003 (Release V-33) 65
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