This standard covers metal-enclosed interrupter (MEI) switchgear assemblies containing, but not limited to, such devices as interrupter switches; selector switches; power fuses; 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 covers metal-enclosed interrupter (MEI) switchgear assemblies containing, but not limited to, such devices as interrupter switches; selector switches; power fuses; 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 1000 V. It includes equipment that is part of primary and secondary unit substations. It does not include gas-insulated substation equipment nor switching devices mounted integrally within a transformer enclosure.

The current standard is being revised to bring it in line with current technology and operating practices. The original standard was approved in 1987 and reaffirmed in 1992. This standard includes equipments that are part of primary and secondary unit substations. Much of this equipment has been or is current being third party certified. This standard is used as the base document for this activity.