CHAPTER 3. POWER SYSTEM ELECTRICAL EQUIPMENT.
3.1 MAJOR APPARATUS. This chapter provides information regarding the requirements for,
and the application of, major apparatus used in an electric power distribution system. More
detailed information on this apparatus is available in trade standards, as well as in manufacturers'
publications and NAVFAC MO-200.
3.1.1 System Components. The major system components described in this chapter are:
Power Circuit Breakers.
Automatic Circuit Reclosers.
3.1.2 Voltage Classes. Power equipment is normally rated according to the nominal system
voltage. In equipment terminology, the voltage ratings fall into four classes:
Low voltage - 600 V or less.
Medium voltage - above 600 V to 72,500 V.
High voltage - above 72,500 V to 242,000 V.
Extra-high voltage - above 242,000 V to 800,000 V.
The equipment discussed in this chapter will generally be in the low and medium voltage classes.
3.1.3 Codes and Standards. In general, system designs and installation practices are governed
by regulations in the National Electric Code (NEC) and the National Electric Safety Code
(NESC). The NEC contains regulations governing the installation of electrical conductors and
equipment within or on public and private buildings, mobile homes, recreational vehicles, float
dwellings, and other premises such as yards, carnivals, parking lots and industrial substations.
The NESC covers standards for safeguarding people from hazards arising from installation,
operation and maintenance of electrical conductors and equipment. The provisions contained in
the NEC define minimum requirements only, and are not intended to be used as design
specifications. Minimum standards relating to electrical equipment have been established by the
National Electrical Manufacturers Association (NEMA), the Institute of Electrical and
Electronics Engineers (IEEE), and the American National Standards Institute (ANSI).