The purpose of this blog is to provide general information 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 Max)” should be consulted. This standards Publication as well as all other NEMA publications are available from IHS @ 800-854-7179

Definitions

*In Non-Hazardous Locations, the specific 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 o 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 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 of 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 4-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 effect on the equipment die to the ingress of water (rain, sleet, snow, splashing water and hose directed water); and that will be undamaged by the external formation of ice on the enclosure.
  • TYPE 4X-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 (windblown dust); to provide a dregree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow, splashing water, and hose directed water); that provides an additional level of protection against corrosion; and that will be undamaged by the external formation of ice on the enclosure.
  • TYPE 6-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 (hose directed water and the entry of water during occasional temporary submersion at a limited depth); and that will be undamaged by the external formation of ice on the enclosure.
  • TYPE 6P-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 (hose directed water and the entry of water during prolonged submersion at a limited depth); that provides an additional level of protection against corrosion and that will undamaged by the external formation of ice on the enclosure.

*In Hazardous locations, when completely and properly installed and maintained, Type 7 and 10 enclosures are designed to contain the internal explosion without causing an external hazard. Type 8 enclosures are designed to prevent combustion through the use of oil -immersed equipment. Type 9 enclosures are designed to prevent the ignition of combustible dust.