IEEE C37.21-2026

This standard covers ratings, construction, and testing of dead-front control switchboards containing, but not limited to, devices such as switches, control devices, instrumentation, metering, monitoring, protective and auxiliary relays, and regulating devices and accessories. It includes switchboards for the control and protection of apparatus used for or associated with power generation, conversion, transmission, and distribution. This standard does not apply to industrial controls, communication equipment, switchboards for use on board ships, or Class 1E switchboards for use in nuclear generating stations, nor does it address human factor considerations. In this standard, dead-front control switchboards are referred to as control switchboards.

This document does not include a purpose clause.

Revision Standard - Active. Ratings, construction, and testing of dead-front control switchboards containing, but not limited to, devices such as switches, control devices, instrumentation, metering, monitoring, alarms, annunciators, protective and auxiliary relays, and regulating devices and accessories are covered in this standard. Switchboards for the control and protection of apparatus used for or associated with power generation, conversion, transmission, and distribution are included, along with control, vertical, dead-front, enclosed, dual, and duplex switchboards. Other construction types, such as control desks, consoles, benchboards, dual and duplex benchboards, fixed rack, cabinet, and swing rack cabinets, are covered by this standard. Industrial controls, communication equipment, switchboards for use on board ships, or Class 1E switchboards for use in nuclear generating stations are not covered.