This standard applies to the Class 1E portions of the following systems and equipment in single-unit and multiunit nuclear power generating stations: -- AC power systems -- DC power systems -- Instrumentation and control (I&C) power systems This standard does not apply to the preferred power supply; the unit generators and their buses; generator breaker; step-up, auxiliary, and start-up transformers; connections to the station switchyard; switchyard; transmission lines; and the transmission network (see Figure 2 and Figure 3). The purpose of this standard is to provide the following: -- The principal design criteria and the design features of Class 1E power systems that enable the systems to meet their functional requirements under the conditions produced by the applicable design basis events -- The requirement for tests and surveillance of Class 1E power systems -- The criteria for sharing Class 1E power systems in multiunit stations -- The requirement for documentation of Class 1E power systems Revision Standard - Superseded. Class 1E portions of ac and dc power systems and I&C power systems in single-unit and multiunit nuclear power generating stations are covered in this standard. The provision of criteria for the determination of Class 1E power system design features, criteria for sharing Class 1E power systems in multiunit stations, the requirements for their testing and surveillance, and the requirements for documentation of the Class 1E power system is the intent of this standard.