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What Are NEMA Standards?

A Guide to NEMA Enclosure Ratings & Types

NEMA enclosures and ratings can be quite confusing if you don’t know what you’re looking for when researching or purchasing an electrical component. Choosing the wrong NEMA enclosure type can result in a financial loss if the rating is too high, or premature failure of the component or possible safety hazards if the rating is too low.

Below, we’ve outlined what NEMA is and what each NEMA enclosure ratings mean.

What Is NEMA?

The National Electrical Manufacturers Association (NEMA) is an organization developed to form the technical standards for the manufacturing of electrical equipment and medical imaging equipment. NEMA works to set industry standards for safety, innovation, interoperability, environment, and market enhancement of our industry.

What Are NEMA Ratings?

Although the NEMA organization oversees a variety of responsibilities in the electrical manufacturing industry, they are most closely associated with the term “NEMA ratings” and the type of enclosure an electrical component is built with.

New NEMA ratings are published every fifth year and are used to protect electrical equipment from damage due to liquids, dust, and/or corrosive chemicals.

It is not mandatory for all electrical components to be designed or built with a NEMA enclosure. Instead, NEMA ratings are merely used as an industry standard and are completely voluntary. At PSI Power & Controls, our electrical equipment is custom-built using NEMA standards

What Do NEMA Ratings Mean?

NEMA 1 – NEMA 1 enclosures are constructed for indoor use and provide protection against human contact with electrically-charged, live electrical parts. It also protects the equipment from falling debris (dirt).

NEMA 2 – A NEMA 2 enclosure is, for all intents and purposes, the same as a NEMA 1 enclosure. However, a NEMA 2 rating additional protection than the NEMA 1, including protection from light dripping or splashing of water (drip-proof).

NEMA 3R, 3RX – NEMA 3R and 3RX enclosures are engineered for indoor or outdoor use and protect against rain, sleet, snow, dirt, and prevents the formation of ice on its enclosure.

NEMA 3, 3X – NEMA 3 and 3X enclosures are rain-tight, sleet-tight, and dust-tight and are made for both indoor and outdoor us. NEMA 3 and 3X designates added protection against dust beyond a NEMA 3R or 3RX enclosure.

NEMA 3S, 3SX – NEMA 3S and NEMA 3SX enclosures benefit from the same protection as a NEMA 3, however provides protection when ice forms on the enclosure and will remain operable when covered in ice.

NEMA 4, 4X – NEMA 4 and NEMA 4X enclosures are intended for indoor or outdoor use and provide the same protections as a NEMA 3 enclosure with additional protection against water ingress and/or hose-directed water. So, if you need to clean off your NEMA 4 enclosure, you don’t have to worry about water damaging your electrical components.

NEMA 6, 6P – Offering the same protection as a NEMA 4 enclosure, NEMA 6 offers protection from temporary or prolonged (6P NEMA rating) water submersion up to a designated depth.

NEMA 7 – Also built for hazardous locations, a NEMA 7 enclosure is explosion proof and made for indoor use (built for hazardous locations).

NEMA 8 – Offering the same protection as a NEMA 7 enclosure, the NEMA 8 can be used both indoor and outdoor (built for hazardous locations).

NEMA 9 – NEMA 9 enclosures are dust ignition proof and intended for indoor use in hazardous locations.

NEMA 10 – NEMA 10 enclosures meet MSHA (Mine Safety and Health Administration) standards.

NEMA 12, 12K – NEMA 12 and NEMA 12K enclosures are intended for general purpose, indoor use. The NEMA 12 and 12K enclosures protect against dripping and splashing water, are rust resistant, and do not include knockouts (partially punched openings that can be removed to accommodate cables, connectors, and/or conduits).

NEMA 13 – NEMA 13 enclosures are for general purpose, indoor use. They provide the same protection as the NEMA 12 enclosures, but with added protection against dripping and/or sprayed oils and coolants.

*Note – An enclosure designated with an “X” indicates a corrosion-resistant rating.

Learn more about NEMA enclosure types »
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Custom-Engineered Electrical Components

Not sure what type of NEMA enclosure is right for your business? Call PSI Power & Controls! Our engineers can design and build a custom electrical component for you. From manual transfer switches to motor starters, contact us today!

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