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

MSHA PROGRAM POLICY MANUAL VOLUME V
circuits as required by Sections 75.803 and this Section.
77.803-2 Ground Check Systems Not Employing Pilot Check Wires;
Approval by the Secretary
High-voltage trailing cables used with ground check systems not
employing ground check wires, as provided in this Section, are not
required to be equipped with installed ground check conductors.
77.805 Cable Couplers and Connection Boxes; Minimum Design
Requirements
Existing medium- and high-voltage cable couplers that are not
equipped with a terminal contact for the ground check conductor
may be used if suitable means are provided for breaking the ground
check conductor first when the coupler is being uncoupled.
Suitable means include the installation of a locking switch on the
coupler so that the coupler cannot be uncoupled until the ground
check conductor is broken, or the installation of an external
ground check connector on the coupler so that the ground check
conductor is broken first when the coupler is being uncoupled.
Except for connections made inside cable connection boxes, totally
enclosed metal switchhouses, etc., this Section expressly
prohibits the use of single-pole couplers (Miller plugs) in
medium- or high-voltage power circuits.
77.808 Disconnecting Devices
A "branch line" means a circuit that is formed by connection to an
existing high-voltage circuit for the purpose of feeding branch
loads. "Visual observation," as referred to in this Section,
means that a physical separation in the current-carrying parts of
the disconnecting device can actually be seen. Enclosed circuit
breakers, oil-filled cutout switches, and other devices which do
not have a visual means of determining that the circuit is
deenergized do not meet the requirements of this Section.
A cable coupler or other device that is not designed for loadbreak
purposes is not acceptable as a disconnecting device unless
it is used in conjunction with a current-interrupting device such
as a circuit breaker or oil-filled cutout which can be used to
deenergize the circuit before the cable coupler or other device is
opened. If a remote switch in the ground check circuit is used to
trip a circuit breaker prior to uncoupling the coupler, visual or
audible evidence must be provided to indicate that the circuit
breaker has opened when the control switch is operated.
February 2003 (Release V-33) 191