WIRING SCHEMES AND GROUNDING

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. Rev. 0 Page 21 ES-15