IEEE C37.20.1-1993

This standard covers metal-enclosed low-voltage power circuit breaker switchgear assemblies containing, but not limited to, such devices as low-voltage power circuit breakers (fused or unfused); other interrupting devices; switches, control, instrumentation, and metering; and protective and regulating equipment. This standard is concerned with enclosed, rather than open, indoor and outdoor switchgear assemblies. It includes types of equipment that are part of secondary unit substations. It does not apply to equipment covered by industrial control standards, communication switchboards, communication switching equipment, switchboards for use on board ships, or dead-front distribution switchboards. In this standard, metal-enclosed low-voltage power circuit breaker switchgear shall be called LV switchgear. For ac LV switchgear, the voltage shall be 1000 V or below; for dc LV switchgear, the voltage shall be 3200 V or below.