To provide protection from potential dangers such as human contact and inclement weather, electrical circuitry and related equipment such as electrical breakers are usually placed inside enclosures. But since some situations call for higher levels of protection than others, not all enclosures are created equal. To provide guidance on levels of protection and construction, the National Electrical Manufacturers Association has issued a set of guidelines that have become accepted across the electrical industry as the de facto standard for electrical enclosures.
Among the range of NEMA ratings, the NEMA 4 enclosure is frequently utilized for its protection against the elements, including cold weather and the formation of ice on the exterior of the enclosure. The NEMA 4 offers an added degree of protection, and is the lowest-rated dustproof NEMA enclosure. In addition, it can protect against splashing water and even hose-directed water. However, it’s not explosion-proof, so it’s not suited for use in more hazardous applications.
In addition, the NEMA 4X enclosure has also been developed. As is easily guessed, the NEMA 4X is a subset of the NEMA 4 rating, so it provides the same level of protection against outdoor weather, particularly against dirt, rain, sleet and windblown dust. It also provides the same level of protection against splashing water.
The difference is that the NEMA 4X must provide additional protection against corrosion beyond that provided by the NEMA 4. As a result, only enclosures fabricated from corrosion-resistant materials, such as stainless steel and aluminum, can qualify for the NEMA 4X rating.
As is the case with many NEMA enclosures, a range of options may also be added, including forced ventilation and interior climate control.