6 December 2006
Including change 1, 7 December 2006
Available Short-Circuit Current--The maximum current that the power system can
deliver through a given circuit point to any negligible impedance short circuit applied at
the given point, or at any other point that will cause the highest current to flow through
the given point.
Barricade--A physical obstruction such as tape, cones, or structures intended to
provide a warning about and to limit access to a hazardous area.
Barrier--A physical obstruction that is intended to prevent contact with equipment or
live parts, or to prevent unauthorized access to a work area.
Blocking--Placing a switch in the open or closed position and mechanically ensuring
the position of the switch cannot be accidentally changed.
--The highest magnitude short circuit current for
a particular fault location.
The impedance at the fault location is usually very low or zero for a bolted fault.
grounding, the permanent joining of metallic parts to form an electrically conductive path
to assure electrical continuity with the capacity to conduct safely any current likely to be
--A conductor used specifically for the purpose
Cardiopulmonary Resuscitation (CPR)
--An emergency medical procedure which
includes opening and maintaining an airway, providing ventilation through rescue
breathing, and providing artificial circulation through the use of external cardiac
Circuit Breakers Incorporating Ground Fault Protection--Circuit breakers that
perform all normal circuit breaker functions and also trip when a current to ground
exceeds some predetermined value.
Clearing Time--The total elapsed time between the beginning of an overcurrent and
the final interruption of the circuit at rated voltage. For a fuse, the clearing time is
considered the sum of the melting time and the arcing time. For a breaker, the clearing
time is the elapsed time between the actuation of a release device and the instant of arc
extinction on all poles of the primary arcing contacts.
Conductor--A material (usually a wire, cable, or bus bar) for carrying an electric
current. Note: This term is used only with reference to current carrying parts which are
sometimes alive (energized).
Cycle--One cycle equals 1/60th of a second for 60 Hz current.