NEMA 1 ENCLOSURES
Type 1 enclosures are intended for indoor use primarily to provide a degree of protection against contact with the enclosed equipment where unusual service conditions do not exist.

NEMA 3 ENCLOSURES
Type 3 enclosures are intended for 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. They shall meet rain, external icing, dust and rust-resistance design tests. They are not intended to provide protection against conditions such as internal condensation or internal icing. 

NEMA 3R ENCLOSURES
Type 3R enclosures are intended for outdoor use primarily to provide a degree of protection against falling rain, and to be undamaged by the formation of ice on the enclosure. They shall meet rain entry, external icing, and rust-resistance design tests. They are not intended to provide protection against conditions such as dust, internal condensation or internal icing. 

NEMA 4X ENCLOSURES
Type 4X enclosures are intended for 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. They shall meet hose down, external icing, and corrosion-resistance design tests. They are not intended to provide protection against conditions such as internal condensation or internal icing. 

NEMA 6 ENCLOSURES
Type 6 enclosures are intended for 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. They shall meet submersions, external icing, and rust-resistance design tests. They are not intended to provide protection against conditions such as internal condensation, internal icing, or corrosive environments 

NEMA 7 ENCLOSURES
Type 7 enclosures are 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 surface to reach temperatures capable of igniting explosive gas-air mixtures in the surrounding atmosphere. Enclosures shall meet explosion, hydrostatic, and temperature design tests. 

NEMA 9 ENCLOSURES
Type 9 enclosures are intended for indoor use in locations classified as 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). 

NEMA 12 ENCLOSURES

Type 12 enclosures are intended for indoor use primarily to provide a degree of protection against dust, falling dirt and dripping non-corrosive liquids.