This standards publication covers enclosures for electrical equipment rated at not more than 1000 volts. It provides description@ features@ and test criteria for hazardous and nonhazardous location enclosures. Definitions are given for general terms and specifically for each enclosure type. Descriptions are given of the more common types of enclosures used by the electrical industry to provide protection to personnel against incidental contact with the enclosed equipment and to provide protection to the enclosed equipment against specific environmental conditions. This standards publication does not cover: enclosures for rotating apparatus; the protection of devices against conditions such as condensation@ icing@ corrosion@ or contamination which may occur within the enclosure or enters via the conduit or unsealed openings@ or; means to prevent attempted entry or operation by unauthorized personnel. This standards publication does not cover requirements for wire and cable. Purpose The primary purpose of this standards publication for enclosures for electrical equipment (1000 volts maximum) is to permit a potential user to determine: 1. The type of enclosure appropriate for the application. 2. The features the enclosure is expected to have 3. The tests applied to the enclosure to demonstrate its conformance to the description.
NEMA 250-1979 history
2014NEMA 250-2014 Enclosures for Electrical Equipment (1000 Volts Maximum)
2008NEMA 250-2008 Enclosures for Electrical Equipment (1000 Volts Maximum)
2003NEMA 250-2003 Enclosures for Electrical Equipment (1000 Volts Maximum)
1997NEMA 250-1997 Enclosures for Electrical Equipment (1000 Volts Maximum)
1991NEMA 250-1991 Enclosures for Electrical Equipment (1000 Volts Maximum)
1985NEMA 250-1985 ENCLOSURES FOR ELECTRICAL EQUIPMENT (1000 VOLTS MAXIMUM); REVISION 1 - MAY 1986@ REVISION 2 - MAY 1988
1979NEMA 250-1979 Enclosures for Electrical Equipment (1000 Volts Maximum) (Revision 1: December 1980; Revision 2: October 1983)