NEMA Enclosures

The National Electrical Manufacturers Association, more commonly known as NEMA, has set forth and defined the standards used for electrical enclosures. These standards are different based on the needs of each type of environment. Ratings focus on environmental protection against hazards that could be corrosive or damaging, along with protection against personnel access. It is important to understand that these are not progressive like other standards such as IP ratings. They do not cover what’s listed for each type plus what is listed for the previous type. They only apply to what is listed for each specific rating.

 NEMA  Protected Against  Description of Protection
 1  Dirt, light, indirect splashing, physical contact with live parts  For use indoors in normal atmospheric conditions. Not dust-tight. Protect workers from hazardous parts and provide some ingress protection.
 2  Dust, light, indirect splashing, dripping liquid, physical contact with live parts  For use indoors in normal atmospheric conditions. Not dust-tight. Drip shields to acquire drip-tight feature. Protect workers from hazardous parts.
 3  Falling dirt, blowing dust, rain, sleet, snow, ice, physical contact with live parts  For use in rugged outdoor applications. I.e., construction areas and ship docks. Weather-resistant. Protect workers from hazardous parts.
 3R  Falling dirt, rain, sleet, snow, ice, physical contact with live parts  For use in rugged outdoor applications. I.e., construction areas and ship docks. Weather-resistant. Protect workers from hazardous parts.
 3S  Falling dirt, blowing dust, rain, sleet, snow, ice, physical contact with live parts  For use in rugged outdoor applications. I.e., construction areas and ship docks. Weather-resistant. Will still operate when weighed down with ice. Protect workers from hazardous parts.
 3X/3RX/3SX  See types above and description for “X” definition  The “X” adds corrosion protection to the pre-defined ratings above. For use near salt water.
 4  65GPM of water from 1” nozzle at 10+ feet for 5 minutes, physical contact with live parts  For use in breweries, ship docks, etc. Watertight. Protect workers from hazardous parts.
 4X  See type 4 and description for “X” definition  The “X” adds corrosion protection to type 4.
 5  Dust, physical contact with live parts  For use in steel mills and cement plants. Provided with necessities to achieve dust-tight standards. Protect workers from hazardous parts.
 6  Submersion, physical contact with live parts  For use in mines, manholes, etc. Temporarily submersible in water or oil. Not intended for continuous submersion. Protect workers from hazardous parts.
 6P  Submersion, physical contact with live parts  For use in mines, manholes, etc. Occasional prolonged submersion. Not intended for continuous submersion. Protect workers from hazardous parts.
 7  See this link for more information: NFPA  For use indoors where there are specific hazardous conditions. Class I, Groups A, B, C, and D defined in the NFPA. Will contain internal explosion.
 8  See this link for more information: NFPA  For use indoors and outdoors where there are specific hazardous conditions. Class I, Groups A, B, C, and D defined in the NFPA. Will contain internal explosion. Prevent Combustion.
 9  See this link for more information: NFPA  For use indoors and outdoors where there are specific hazardous conditions. Class II, Groups E, F, and G defined in the NFPA. Will contain internal explosion. Prevent ignition of combustible dust.
 10  See this link for more information: MSHA  Meets requirements of Mine Safety and Health Administration, 30 CFR Part 18 (1978). Will contain internal explosion.
 11  Corrosive liquids and gases  For general purpose use. Drip and corrosion resistant.
 12/12K  Dust, falling dirt, dripping (non-corrosive) liquids, physical contact with live parts  For general purpose, indoor use. Drip, dust, and rust resistant. Protect workers from hazardous parts. No knockouts.
 13  Dust, spraying water, non-corrosive coolants, physical contact with live parts  For general purpose use. Oil exclusion and rust resistant. Protect workers from hazardous parts.

See table below for a NEMA conversion to IP ratings.

Table A-1 above is from the official NEMA site. It can be found here: http://www.nema.org/Products/Documents/nema-enclosure-types.pdf

About this author

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Ashley Awalt is a Technical Content Developer that has been with Digi-Key Electronics since 2011. She earned her Associate of Applied Science degree in Electronics Technology & Automated Systems from Northland Community & Technical College through the Digi-Key scholarship program. Her current role is to assist in creating unique technical projects, documenting the process and ultimately participating in the production of video media coverage for the projects. In her spare time, Ashley likes to – oh, wait, is there such a thing as spare time when you’re a mom?

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