NEMA ratings – enclosure classifications and types

NEMA 1:  General purpose – intended for indoor use primarily to provide a degree of protection against contact with the enclosed parts in locations without unusual service conditions. 

NEMA 2: Drip proof – intended for indoor use primarily to provide a degree of protection against limited amounts of falling water or dirt.

NEMA 3: Rain-tight, dust tight, and sleet (ice) resistant – intended for outdoor use with primarily to provide a degree of protection from windblown dust, rain, sleet, and undamaged by ice formation.

NEMA 3S: Rain-tight, dust-tight, and sleet (ice) resistant - intended for outdoor use primarily to provide a degree of protection against wind-blown dust, rain, sleet, and external mechanism remains operable when ice laden.

NEMA 3R: Rain-tight, dust-tight, and sleet (ice) resistant - intended for outdoor use primarily to provide a degree of protection against falling rain and sleet, undamaged by the formation of ice on the enclosure.

NEMA 4: Watertight and Dust tight –  intended for indoor/outdoor use to provide a degree of protection  against splashing water, water seepage, falling or hose directed water and sever external condensation, undamaged by the formation of ice on the enclosure.

NEMA 4X: Watertight and Dust tight, and corrosion resistant: - same as NEMA 4 with addition of corrosion resistance.

NEMA 6: Submersible – intended for indoor/outdoor use to provide a degree of protection against entry of water during submersion at a limited depth.

NEMA 6P: Submersible – same as a type 6 enclosure, but provides prolonged submersion protection at a limited depth.

NEMA 7: Explosion Proof (class I, division 1, A, B, C, D) designed to contain an internal explosion without causing an external hazard when installed in a designated atmospheres and locations. Class I, Division 1 locations are those in which hazardous atmospheres are, or may be, present under normal operating conditions.

Group A = atmospheres containing acetylene.

Group B = atmospheres containing hydrogen.

Group C = atmospheres containing ethyl-ether vapors, ethylene, or cycopropane.

Group D = atmospheres containing gasoline, hexane, naphtha, benzene, butane, propane, alcohol, acetone, benzol, lacquer, solvent vapors, and natural gas.

NEMA 9: Explosion Proof (class II, division 1, E, F, G,) – Dust-ignition-proof enclosures designed to prevent the entrance of dust and the enclosure devices do not produce sufficient heat to cause external surface temperatures capable if igniting dust on the enclosure or in the surrounding atmosphere. Class II, Division 1 locations are those in which combustible dust is, or may be, present under normal conditions.  

Article Title:
NEMA ratings – enclosure classifications and types
Article Summary:
Enclosure Classifications and Types
Article Date:
1/4/2008
Article ID:
785
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