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 />
<strong>Mine</strong>s using single-phase power originating at the power company's<br />
secondary <strong>and</strong> extending underground cannot normally comply with<br />
this Section due to the power company's practice of connecting<br />
the lightning arrester ground to the grounded neutral which also<br />
connects to the center tap of the transformer, unless an<br />
isolation transformer is installed or the power company isolates<br />
the lightning arrester ground from the center tap ground <strong>and</strong> a<br />
separate neutral ground field is established.<br />
75.523-1 Deenergization of Self-Propelled Electric Face<br />
Equipment Installation Requirements<br />
A machine that can only be operated from a remote location is not<br />
required to be provided with a device that will quickly<br />
deenergize the tramming motors of the machine in the event of an<br />
emergency. However, if at any time the remote controls are<br />
placed on the machine for the purpose of tramming the machine, or<br />
if for any other reason the operator trams the machine from<br />
onboard or alongside the machine, the machine shall be provided<br />
with a device that meets the requirements of this Section <strong>and</strong><br />
Section 75.523-2.<br />
Any device other than a bar or lever used for deenergizing<br />
tramming motors such as a "dead man control" can be accepted only<br />
by an approval letter from Technical Support.<br />
75.523-2 Deenergization of Self-Propelled Electric Face<br />
Equipment; Performance Requirements<br />
The actuating bar or lever <strong>and</strong> its associated linkage should be<br />
designed to activate a circuit breaker, control switch, hydraulic<br />
valve, or other device that will deenergize the tramming motors<br />
when the actuating bar or lever is depressed.<br />
The bar or lever shall extend a sufficient distance in each<br />
direction to provide a ready means of deenergizing the tramming<br />
motors without requiring the operator to change position or<br />
search for a safe stop switch if an emergency occurs.<br />
The actuating bar or lever shall be designed so that a horizontal<br />
or vertical (downward) pressure of 15 pounds force shall cause<br />
deenergization of the tramming motors before the bar has traveled<br />
more than 2 inches.<br />
February 2003 (Release V-33) 68
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