National Electrical Manufacturers Association
(NEMA Standard 250)

Type

 1  Enclosures are intended for indoor use primarily to 
    provide a degree of protaction against contact with the 
    enclosure equipemnt or locations where unusual service 
    conditions do not exist.

 2  Enclosures are intended for indoor use primarily to 
    provide a degree of protection against limited amounts 
    of falling water and dirt.

 3  Enclosures are intended for outdoor use primarily to 
    provide a degree of protection against windblown dust,c 
    rain, and sleet; undamaged by formation of ice on the 
    enclosure.

 3R Enclosures are intended for outdoor use primarily to 
    provide a degrre of protaction against falling rain and 
    sleet; undamaged by the formation of ice on the 
    enclosure.

 4  Enclosures are intended for indoor or outdoor use 
    primarily to provide a degree of protaction against wind 
    blown dust and rain, splashing water, and hose-direct 
    water; undamaged by the formation of Ice on enclosure.

 4X Enclosures are intended for indoor or outdoor use 
    primarily to provide a degree of protaction against 
    corrosion, wind blown dust and rain, splashing water, 
    and hose-direct water; undamaged by the formation of Ice 
    on enclosure.

 5  No NEMA equivalent.  Superseded by Type 12 for control
    apparatus.

 6  Enclosures are intended for use indoors or outdoors 
    where occassional submersion is encountered.

 7  Enclosures are intended for use indoor in Class I, 
    Group A, B, C or D hazardous locations; airbreak 
    equipment.

 8  Enclosures are intended for use indoor in Class I, 
    Group A, B, C or D hazardous locations; oil-immersed 
    equipment.

 9  Enclosures are intended for use indoor in Class II, 
    Group E, F, or G hazardous locations; airbreak 
    equipment.

10  Bureau of Mines

11  Enclosures are intended for indoor.  Corrosion 
    resistant and dripproof; oil-immersed equipment.

12  Enclosures are intended for indoor use primarily to 
    provide a degree of protection against dust, falling 
    dirt, and dripping noncorrosive liquids.

13  Enclosures are intended for indoor use primarily to 
    provide a degreee of protection against dust, spraying 
    of water, oil, and noncorrosive coolant.

The preceding descriptions are not intended to be complete 
representations of National Electrical Manufacturers 
Association standards for enclosures.