These requirements cover metal-enclosed low-voltage power circuit breaker switchgear assemblies containing but not limited to such devices as low-voltage power circuit breakers@ other interrupting devices@ switches@ control@ instrumentation and metering@ protective and regulating equipment. These requirements cover equipment intended for use in ordinary locations in accordance with the National Electrical Code. These requirements are intended to supplement and be used in conjunction with the Standard for Metal-Enclosed Low Voltage Power Circuit Breaker Switchgear@ ANSI C37.20.1@ and the Standard for Conformance Testing of Metal-Enclosed Low-Voltage AC Power Circuit Breaker Switchgear Assemblies@ ANSI C37.51. These requirements cover equipment rated 600 V ac or less nominal@ 635 V ac maximum.