Nema Enclosure Definition

NEMA defines standards for various grades of electrical enclosures typically used in industrial applications. Each is rated to protect against designated environmental conditions. A typical NEMA box or case might be rated to provide protection against environmental hazards such as water, dust, oil or coolant or atmospheres containing corrosive agents such as acetylene or gasoline.


The following is a list of the ratings and what they mean:

  • 1 -- General-purpose. Protects against dust, light, and indirect splashing but is not dust-tight; primarily prevents contact with live parts; used indoors and under normal atmospheric conditions.
  • 2 -- Drip-tight. Similar to Type 1 but with addition of drip shields; used where condensation may be severe (as in cooling and laundry rooms).
  • 3, 3S, 3X -- Weather-resistant. Protects against weather hazards such as rain and sleet; used outdoors on ship docks, in construction work, and in tunnels and subways. 3X includes corrosions.
  • 3R -- Intended for outdoor use. Provides a degree of protection against falling rain and ice formation. Meets rod entry, rain, external icing, and rust-resistance design tests.
  • 4 and 4X -- Watertight (weatherproof). Must exclude at least 65 GPM of water from 1-in. nozzle delivered from a distance not less than 10 ft for 5 min. Used outdoors on ship docks, in dairies, and in breweries. The 4X model has corrosion resistance.
  • 5 -- Dust-tight. Provided with gaskets or equivalent to exclude dust; used in steel mills and cement plants.
  • 6 and 6P -- Submersible. Design depends on specified conditions of pressure and time; submersible in water or oil; used in quarries, mines, and manholes.
  • 7 -- Hazardous. For indoor use in Class I, Groups A, B, C, and D environments as defined in the NEC.
  • 8 -- Hazardous. For indoor and outdoor use in locations classified as Class I, Groups A, B, C, and D as defined in the NEC.
  • 9 -- Hazardous. For indoor and outdoor use in locations classified as Class II, Groups E, F, or G as defined in the NEC.
  • 10 -- MSHA. Meets the requirements of the Mine Safety and Health Administration, 30 CFR Part 18 (1978).
  • 11 -- General-purpose. Protects against the corrosive effects of liquids and gases. Meets drip and corrosion-resistance tests.
  • 12 and 12K -- General-purpose. Intended for indoor use, provides some protection against dust, falling dirt, and dripping noncorrosive liquids. Meets drip, dust, and rust resistance tests.
  • 13 -- General-purpose. Primarily used to provide protection against dust, spraying of water and noncorrosive coolants. Meets oil exclusion and rust resistance design tests.

In this real-world application, a NetDog is used to monitor a system using a NEMA Case.

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