About NEMA Enclosure Types

The purpose of the following pages is to provide general information on the definitions of NEMA Enclosure Types to architects, engineers, installers, inspectors and other interested parties.  [For more detailed and complete information, NEMA Standards Publication 250-2003, “Enclosures for Electrical Equipment (1000 Volts Maximum)” should be consulted.] 


Definitions
[from NEMA 250-2003]


In Non-Hazardous Locations, the specific enclosure Types, their applications, and the environmental conditions they are designed to protect against, when completely and properly installed, are as follows:

Type 1    Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts and to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt).

Type 2    Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); and to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing).

Type 3    Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.


Type 3R    Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.

Type 3S    Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and for which the external mechanism(s) remain operable when ice laden.

 

NEMA Enclosures: Types 3X, 3RX, 3SX, 4, 4X >>

NEMA Enclosures: Types 5, 6, 6P, 12, 12K, 13 >>

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