A transfer switch can be damaged or create dangerous conditions if it is exposed to dirt or water. Therefore, it is essential that the transfer switch has an enclosure designed for the location and the risks it will be exposed to.
NEMA stands for National Electrical Manufacturers Association. NEMA represents nearly 325 electrical equipment and medical imaging manufacturers who make safe, reliable, and efficient products and systems.
For those who like the full technical definition keep reading. We included some pictures for the visual learners.
NEMA 1
For indoor use only.
The NEMA 1 enclosure protects personnel from gaining easy access to hazardous parts. Also, it will protect the equipment inside the enclosure of falling dirt.
NEMA 3R
For indoor or outdoor use.
The NEMA 3R enclosure protects personnel from gaining easy access to hazardous parts. Also, it will protect the equipment inside the enclosure of falling dirt, and the formation of ice. It also has an ingress protection of rain, sleet, snow.
NEMA 4
For indoor or outdoor use.
The NEMA 4 enclosure protects personnel from gaining easy access to hazardous parts. Also, it will protect the equipment inside the enclosure of falling dirt, windblown dust, rain, sleet, snow, and the formation of ice. It also has an ingress protection of splashing water, hose directed water.
NEMA 4X
For indoor or outdoor use.
The NEMA 4X enclosure protects personnel from gaining easy access to hazardous parts. Also, it will protect the equipment inside the enclosure of windblown dust, rain, sleet, snow, additional level of protection against corrosion, and the formation of ice. It also has an ingress protection of splashing water, hose directed water.
NEMA 12
For indoor use only.
The NEMA 12 enclosure (without knockouts) protects personnel against access to hazardous parts. Also, it will protect the equipment inside the enclosure of falling dirt, circulating dust, fibers. It also has an ingress protection of dripping and a light splashing of water.