IEEE C37.21:2005 (R2010)

Revision Standard - Superseded.
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, alarms, annunciators, protective and auxiliary relays, and regulating devices and accessories. It includes, but is not specifically limited to, switchboards for the control and protection of apparatus used for or associated with power generation, conversion, transmission, and distribution. Types of switchboards may include control, vertical, dead-front, enclosed, dual, or duplex switchboards. Other construction types include control desks, consoles, benchboards, dual or duplex benchboards, fixed rack, cabinet, and swing rack cabinets. It does not apply to industrial controls, communication equipment, switchboards for use on board ships, or Class 1E switchboards for use in nuclear generating stations.

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.
This project will modify all dimensional information to provide metric dimensions. This is necessary to gain global acceptance of this standard. Also, due to changes in related standards (e.g. C37.20.1 and C37.20.2) revisions will be made to provide similar requirements between these related standards.