NEMA enclosures are a type of electrical enclosure that meets the National Electrical Manufacturers Association (NEMA) standards for protection against environmental conditions such as dust, water, and corrosive materials. The rating system defines the type and degree of protection provided by the enclosure, ranging from NEMA 1 (protection against dust and falling dirt) to NEMA 13 (protection against dust, water, and oil).
NEMA enclosures are commonly used to house and protect electrical equipment such as switches, circuit breakers, and control panels. Choosing the right rating for a specific application depends on several factors, such as the type of equipment to be protected, the environmental conditions of the installation site, and any specific safety regulations that apply to the installation.
Non-Hazardous Locations
When properly and completely installed in non-hazardous locations NEMA enclosures are rated as follows:
Type 1 - General purpose for use indoors. NEMA Type 1 enclosures provide protection to personnel against access to hazardous parts and protect equipment inside the enclosure against solid foreign objects, such as falling dirt.
Type 2 – Drip-Proof for use indoors. NEMA Type 2 enclosures provide the same protections as Type 1 with an added degree of protection against dripping and light splashing of liquids.
Type 3 - Dusttight, Raintight, Sleettight for use indoors or outdoors. NEMA Type 3 enclosures provide the same protection as Type 1 with an added degree protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow) and windblown dust. Enclosure will not be damaged by the external formation of ice on the enclosure.
Type 3R – Raintight, Sleet Resistant for use indoors or outdoors. NEMA Type 3R enclosures provide the same protection as Type 1 with an added degree protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow). Enclosure will not be damaged by the external formation of ice on the enclosure.
Type 3S - Dusttight, Raintight, Sleettight for use indoors or outdoors. NEMA Type 3S enclosures provide the same protection as Type 1 with an added degree protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow) and windblown dust. External mechanism(s) will remain operable when ice laden.
Type 3X – Dusttight, Raintight, Sleettight, Corrosion-Resistant for use indoors or outdoors. NEMA Type 3X enclosures enclosures provide the same protection as Type 1 with an added degree protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow) and windblown dust with an added level of protection against corrosion. Enclosure will not be damaged by the external formation of ice on the enclosure.
Type 3RX – Raintight, Sleet Resistant, Corrosion-Resistant for use indoors or outdoors. NEMA Type 3RX enclosures provide the same protection as Type 1 with an added degree protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow) with an added level of protection against corrosion. Enclosure will not be damaged by the external formation of ice on the enclosure.
Type 3SX - Dusttight, Raintight, Sleettight, Corrosion-Resistant for use indoors or outdoors. NEMA Type 3SX enclosures provide the same protection as Type 1 with an added degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow) and windblown dust with an added level of protection against corrosion. External mechanism(s) will remain operable when ice laden.
Type 4 - Watertight, Dusttight, Sleet Resistant for use indoors and outdoors. NEMA Type 4 enclosures provide the same protection as Type 1 with an added degree 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) and windblown dust. Enclosure will be not be damaged by the external formation of ice on the enclosure.
Type 4X - Watertight, Dusttight, Corrosion-Resistant for use indoors and outdoors. NEMA Type 4X enclosures provide the same protection as Type 1 with an added degree of protection with respect to harmful effects on the equipment due to the ingress of windblown dust and water (rain, sleet, snow, splashing water, and hose directed water) with an added level of protection against corrosion. Enclosure will not be damaged by the external formation of ice on the enclosure.
Type 5 - Dusttight, Drip-Proof for use indoors. NEMA Type 5 enclosures provide protection to personnel against access to hazardous parts and protect equipment inside the enclosure against solid foreign objects, such as falling dirt and settling airborne dust, lint, fibers, and flyings with an added degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing).
Type 6 - Occasionally Submersible, Watertight, Sleet Resistant for use indoors and outdoors. NEMA Type 6 enclosures provide the same protection as Type 1 with an added 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). Enclosure will not be damaged by the external formation of ice on the enclosure.
Type 6P - Watertight, Sleet Resistant Prolonged Submersion for use indoors and outdoors. NEMA Type 6P enclosures provide the same protections as Type 6 with an added level of protection against corrosion. Enclosure will not be damaged by the external formation of ice on the enclosure.
Type 12 - Dusttight and Driptight for use indoors. NEMA Type 12 enclosures are constructed without knockouts and provide protection to personnel against access to hazardous parts and protect equipment inside the enclosure against solid foreign objects, such as falling dirt and circulating dust, lint, fibers, and flyings with an added degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing).
Type 12K - Dusttight and Driptight, with Knockouts for use indoors. NEMA Type 12 enclosures are constructed with knockouts and provide the same protections as Type 12.
Type 13 - Oiltight and Dusttight for use indoors. NEMA Type 13 enclosures provide protection to personnel against access to hazardous parts and protect equipment inside the enclosure against solid foreign objects, such as falling dirt and circulating dust, lint, fibers, and flyings with an added degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing) and protection against the spraying, splashing, and seepage of oil and non-corrosive coolants.
Hazardous Locations
When properly and completely installed and maintained in hazardous locations NEMA enclosures are rated as follows:
Type 7 enclosures are constructed for indoor use in hazardous (classified) locations classified as Class I, Division 1, Groups A, B, C, or D as defined in NFPA 70. NEMA Type 7 enclosures are designed to contain an internal explosion without causing an external hazard.
Type 8 enclosures are constructed for either indoor or outdoor use in hazardous (classified) locations classified as Class I, Division 1, Groups A, B, C, and D as defined in NFPA 70. NEMA Type 8 enclosures are designed to prevent combustion through the use of oil-immersed equipment.
Type 9 enclosures are constructed for indoor use in hazardous (classified) locations classified as Class II, Division 1, Groups E, F, or G as defined in NFPA 70. NEMA Type 9 enclosures are designed to prevent the ignition of combustible dust.
Type 10 enclosures are constructed to meet the requirements of the Mine Safety and Health Administration, 30 CFR, Part 18. NEMA Type 10 enclosures are designed to contain an internal explosion without causing an external hazard.
