Electrical Distribution Systems
WIRING SCHEMES AND GROUNDING
WIRING SCHEMES AND GROUNDING
Nuclear facilities rely on standardized wiring schemes to provide both single-
phase and three-phase power distribution systems and protective grounds to insure
safe operation.
EO 1.9
DEFINE the following terms as they apply to wiring
schemes used in power distribution systems:
a.
Ampacity
b.
Bond
c.
Conductor
d.
Ground
e.
Ground voltage
f.
Leg
g.
Neutral
h.
Phase voltage
EO 1.10
DESCRIBE the two methods of connecting single-
phase loads to a three-phase power source.
EO 1.11
DESCRIBE the purpose of the following power
distribution schemes.
a.
3-wire, single-phase Edison system
b.
3-wire, three-phase Delta system
c.
4-wire, three-phase Delta system
d.
4-wire, three-phase Wye system
Introduction
Many advisory boards exist to insure the standardization of electrical installations in accordance
with accepted designs and safe practices. The Institute of Electrical and Electronics Engineers
(IEEE) and the American National Standards Institute (ANSI) are two advisory boards that have
published numerous standards. These standards are utilized by the Department of Energy and
the nuclear industry. However, for a day-to-day practical guide for noncritical installations, the
recognized guide is the National Electrical Code Handbook (NEC), published by the National
Fire Protection Association and endorsed by ANSI. The NEC Handbook is the primary source
of much of the material presented in this chapter and may serve as a ready reference for specific
questions not covered in this fundamental discussion.
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