This standard covers metal-enclosed interrupter (MEI) switchgear assemblies containing, but not limited to, such devices as interrupter switches; selector switches; power fuses; circuit breakers; control, instrumentation and metering devices; and protective equipment. It includes, but is not specifically limited to, equipment for the control and protection of apparatus used for distribution of electrical power. This standard is concerned with enclosed (rather than open), indoor and outdoor switchgear assemblies rated above 1 kV. It includes equipment that is part of primary and secondary unit substations. It does not include gas-insulated substation equipment or switching devices mounted integrally within a transformer enclosure. The purpose of this standard is to provide the usual service conditions, definition of ratings, preferred ratings, design and production tests, construction requirements, an application guide, and a guide for handling, storage, and installation for MEI switchgear. Revision Standard - Superseded. Metal-enclosed interrupter (MEI) switchgear assemblies containing, but not limited to, such devices as interrupter switches; selector switches; power fuses; circuit breakers; control, instrumentation and metering devices; and protective equipment are included in this standard. It includes, but is not specifically limited to, equipment for the control and protection of apparatus used for distribution of electrical power.