Rack enclosures are rated based on their suitability for certain applications and the degree to which they protect equipment. Each type of enclosure is given a number based on its ability to withstand environmental factors.



There are two main standards: (National Electrical Manufacturers Association) in the U.S., and (International Electrotechnical Commission) worldwide. See the charts below for each standard's rating descriptions.

NEMA identifies enclosures with a number to represent their specific protection qualities. : NEMA 7, 8, 9 and 10 type enclosures are designated for use in hazardous locations. See the National Electrical Code (NEC) for more information.

Type: Protects Against:

1 Limited amounts of falling dirt

3 Rain, sleet, windblown dust, and damage from external ice formation

3R Rain, sleet, and damage from external ice formation

3S Rain, sleet, windblown dust, and damage from external ice formation; plus provides for operation of external mechanisms when ice laden

4 Windblown dust and rain, splashing water, hose-directed water, and damage from external ice formation

4X Corrosion, windblown dust and rain, splashing water, hose-directed water, and damage from external ice formation

6 Hose-directed water, entry of water due to occasional temporary submersion (depth limited) and damage from external ice formation

6P Hose-directed water, entry of water due to prolonged submersion (depth limited) and damage from external ice formation

7 Conditions in locations classified as Class I, Groups A, B, C, or D, as defined in the NEC (National Electrical Code)

8 Conditions in locations classified as Class I, Groups A, B, C, or D, as defined in the NEC

9 Conditions in locations classified as Class II, Groups E, F, or G, as defined in the NEC

10 Mine conditions as defined by the Mine Safety and Health Administration

12 Circulating dust, falling dirt, and dripping non-corrosive liquids

12K Same as type 12 but with knockouts