Industrial enclosures come in a wide variety of shapes and sizes. When purchasing an enclosure, you will likely have many options to choose from and many decisions to make. Fortunately, this means you will be more likely to easily find the indoor or outdoor enclosure that fits your needs. One very important decision you'll need to make is determining the National Electrical Manufacturers Association (NEMA) rating requirement you'll need your enclosure to meet.

NEMA is the trade association for the electrical manufacturing industry. This association provides technical standards that are in the best interest of the electrical manufacturing industry and users. When shopping for your indoor or outdoor enclosure, you'll probably note a NEMA rating assigned to each enclosure type. Understanding these ratings is important to your shopping process and to ensure you purchase the right kind of enclosure for your needs.

There are 13 levels of NEMA ratings. A rating of 1 or 2 indicates an plastic enclosure approved for indoor use. A level 1 enclosure protects equipment from contact with people or falling dirt. Level 2 offers the same protection, but also protects from lightly splashing liquids.

NEMA 3, 3R and 3S ratings are indicated for both indoor and outdoor enclosures. All three levels protect equipment from incidental contact, falling dirt, rain, sleet and snow. Level 3 also protects from windblown dust and indicates that the enclosure will be undamaged by the formation of ice. Level 3R does not protect against windblown dust. Level 3S does protect against windblown dust and also indicates that external mechanisms on the enclosure will remain operable when ice laden.

NEMA 4 and 4X rated enclosures may be for use indoors or outdoors and provide protection against incidental contact, falling dirt, rain, sleet, snow, windblown dust, splashing water and hose-directed water. These enclosures will also be unharmed by the formation of ice. NEMA 4X type enclosures also protect against corrosion.

Type 5 enclosures are for indoor use only and provide protection from incidental contact, falling dirt, settling airborne dust, lint, fibers and flyings. These enclosures also protect against dripping and light splashing of liquids.

Enclosures with a 6 or 6P rating may be for indoor or outdoor use and will protect against incidental contact, falling dirt, hose-directed water and the entry of water during temporary submersion at a limited depth. These will also be unharmed by the formation of ice on the exterior. A 6P rated enclosure will also protect against the entry of water during prolonged submersion at limited depths.

NEMA 7 rated enclosures are indicated for those constructed for indoor use in hazardous or classified locations. Level 8 enclosures may be for indoor or outdoor use and are also indicated for use in hazardous or classified locations. These two levels are used in Class I; Division; and Groups A, B, C, or D classified locations. NEMA 9 enclosures are for indoor use in Class II; Division I; and Groups E, F, or G classified locations. Type 10 enclosures meet the requirements of the Mine Safety and Health Administration.

Ratings of 11 are intended for indoor use and are corrosion resistant and drip proof. NEMA 12 and 12K ratings are also intended for indoor use and protect against falling dirt, circulating dust, lint, fibers and flyings, dripping and light splashing of liquids. Enclosures rated 12 are constructed without knockouts, while 12K rated enclosures are constructed with knockouts.

NEMA 13 rated enclosures are for indoor use and designed to protect against falling dirt, circulating dust, lint, fibers and flyings as well as against the spraying, splashing and seepage of water, oil and non-corrosive agents.

Understanding NEMA ratings will ensure that you purchase the enclosure that's right for your needs. All indoor and outdoor enclosures should be NEMA rated. These ratings not only help ensure industry standards and best practices are maintained, they are also there to help make your buying process go smoothly.