Type NEMA stands for the National Electrical Manufacturers Association. It has established a range of standards for electrical equipment enclosures.
Type NEMA 1 General Purpose - Indoors:Type 1 - intended for general purpose indoor use primarily to provide a degree of protection against contact with the enclosed equipment or locations where unusual service conditions do not exist.
Type NEMA 2 Drip Proof - Indoors:
Type 2 - intended for general purpose indoor use primarily to provide a degree of protection against limited amounts of falling water and dirt.
Type NEMA 3 Dust Tight, Rain Tight, & Ice/Sleet resistant - Indoors/Outdoors:
Type 3 - intended for general purpose outdoor use primarily to provide a degree of protection against windblown dust, rain, and sleet; and to be undamaged by the formation of ice on the enclosure.
Type NEMA 3R Rain Proof & Ice/Sleet Proof - Indoors/Outdoors:
Type 3R - intended for general purpose outdoor use primarily to provide a degree of protection against falling rain; and to be undamaged by the formation of ice on the enclosure.
Type NEMA 3S Dust Tight, Rain Tight, & Ice/Sleet Proof - Outdoors:
Type 3S - intended for general purpose outdoor use primarily to provide a degree of protection against sleet; and to be undamaged by the formation of ice on the enclosure.
Type NEMA 4 Water Tight & Dust Tight - Indoors/Outdoors:
Type 4 - intended for general purpose indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, and hose directed water; and to be undamaged by the formation of ice on the enclosure.
Type NEMA 4x Water Tight, Dust Tight, & Corrosion Resistant - Indoors/Outdoors:
Type 4X - intended for general purpose indoor and outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, and hose-directed water; and to be undamaged by the formation of ice on the enclosure.
Type NEMA 5 Superseded by NEMA 12 for Control Apparatus:
Type 5 - see Type NEMA 12
Type NEMA 6 Submersible, Water Tight, Dust Tight, & Ice/Sleet Resistant - Indoors/Outdoors:
Type 6 - intended for general purpose indoor or outdoor use primarily to provide a degree of protection against the entry of water during temporary submersion at a limited depth; and to be undamaged by the formation of ice on the enclosure.
Type NEMA 7 Underwriters Lab Class 1-Groups C&D -Explosion Proof - Indoors:
Type 7 - for indoor use in locations classified as Class I, Groups A, B, C, or D, as defined in the National Electrical Code.
Type 7 enclosures shall be capable of withstanding the pressures resulting from an internal explosion of specified gases, and contain such an explosion sufficiently that an explosive gas-air mixture existing in the atmosphere surrounding the enclosure will not be ignited. Enclosed heat generating devices shall not cause external surfaces to reach temperatures capable of igniting explosive gas-air mixtures in the surrounding atmosphere. Enclosures shall meet explosion, hydro-static, and temperature design tests.
Type NEMA 8 Underwriters Lab Class 1-Groups C&D -Explosion Proof - Indoors:
Type 8 is same as Type NEMA 7, except the unit is oil-immersed
Type NEMA 9 Underwriters' Lab Class II - Groups E,F,G - Indoors:
Type 9 - intended for special purpose indoor use in locations classified as hazardous (Class II, Groups E, F, or G, as defined in the National Electrical Code).
Type 9 enclosures shall be capable of preventing the entrance of dust. Enclosed heat generating devices shall not cause external surfaces to reach temperatures capable of igniting or discoloring dust on the enclosure or igniting dust-air mixtures in the surrounding atmosphere. Enclosures shall meet dust penetration and temperature design tests, and aging of gaskets (if used).
Type NEMA 10 Bureau of Mines:
Type NEMA 11 Corrosion Resistant & Drip Proof - Oil Immersed - indoors:
Type NEMA 12 Industrial Use - Dust Tight & Drip Tight - Indoors:
Type 12 - intended for industrial indoor use primarily to provide a degree of protection against dust, falling dirt, and dripping noncorrosive liquids.
Type NEMA 13 Oil Tight & Dust Tight - Indoors:
Type 13 - intended for industrial indoor use primarily to provide a degree of protection against dust, spraying of water, oil, and noncorrosive coolant.