NEMA refers to the National Electrical Manufacturer’s Association. This group focuses on developing product standards, government standards, and market economics (per their website www.nema.org). The electrical industry has adopted NEMA’s standard and testing requirements for rating electrical enclosures. Although NEMA does not offer any testing or certifying services, we refer to enclosures by their NEMA rating.

Enclosures are rated based on their ability to restrict access to hazardous parts, restrict ingress of varying agents, deal with submersion, resist corrosive environments, and contain internal explosions. There are multiple classifications each with their own testing requirements. The basic indoor electrical enclosure is a NEMA 1 enclosure, which is tested to restrict access to hazardous parts and ingress of falling dirt. A basic outdoor electrical enclosure is a NEMA 3R, which has been tested to restrict access to hazardous parts and ingress of rain, sleet, and snow.

“Use the right tool for the right job” correlates to “use the proper enclosure for the right atmosphere”. The National Electrical Code (NEC) requires enclosures to be selected based on location conditions (NEC 110.28). NEC 500 through 504 identify additional requirements for enclosures to be used in a hazardous location. Hazardous environments refer to areas where combustible gases or dusts may be present in large enough quantities to present a hazard to the surrounding area.

The results from using an inadequate enclosure can involve personal injury and equipment damage. Try to remember that the rules and standards are in place to help keep everyone safe.

-M