NEMA 4 (along with its sister rating NEMA 4X) is the most commonly specified NEMA enclosure rating in North America. NEMA 4 rated boxes protect sensitive electronics against the moisture found in factory washdown and outdoor applications, and they defend designs against airborne dust and dirt.
To meet the requirements of NEMA 4, a box must withstand hose directed water without allowing water to enter. Lower ratings such as NEMA 12 protect only against dripping or splashing water, so NEMA 4 is a higher level of protection.
Bud offers a huge selection of NEMA 4 rated boxes. Use filters to search by size and style.
Learn about the differences between NEMA 3 rated enclosure and NEMA 4 rated enclosure.
Although the classic NEMA 4X box is made of stainless steel, today, the boxes are made from many types of materials, including extruded aluminum, die-cast aluminum, polycarbonate plastic, and fiberglass. These are excellent alternatives because the high cost of the material makes stainless steel enclosures very expensive.
Stainless steel enclosures are a good choice when high strength and extreme corrosion protection are essential. Nevertheless, in most cases, a NEMA 4x enclosure made of other materials would be a better choice. If aggressive chemicals are present, note that the box seals should be selected for compatibility.
Confusingly, NEMA 4 enclosures have a higher level of protection than a NEMA 12 enclosure. Unlike IP ratings, it is not always the case that a higher number NEMA rating indicates higher protection.
A NEMA 12 enclosure protects against light dripping and splashing of water as well as leaking and dripping of oil and coolants. It is for indoor use only. For an outdoor application, select an enclosure with at least a NEMA 4 or NEMA 4X rating. This is because NEMA 4 and NEMA 4x boxes are sealed against water ingress, whereas NEMA 12 enclosures are not. For this reason, NEMA 4 and 4X are also the choices for indoor locations subject to washdown.
Generally, NEMA 12 boxes are more economical, so select the minimum rating needed for the application. For a complete explanation of NEMA ratings, see our NEMA rating guide for electronic enclosures.
NEMA 4 box enclosures seal out moisture, making them waterproof for most applications, as they withstand wind-driven rain and plant equipment washdowns. However, they are not waterproof in the sense of being submersible. The pressure of water, especially at depth, will eventually force water into the enclosure. The NEMA 6P rating (along with IP ratings IP67 and IP68) address enclosures that are temporarily submersible. See our broad line of waterproof enclosures.
Enclosures rated NEMA 4X are used outdoors, especially where corrosion is a concern, such as marine and coastal locations with salty air, and where corrosive chemicals are present, such as water treatment facilities. Indoors, NEMA 4X boxes are used where chemicals may contact the enclosure, such as pulp and paper facilities. Processing facilities for food, chemicals, and pharmaceuticals wash down their equipment regularly to maintain a hygienic environment; the forceful spray of water and cleaning chemicals require NEMA 4X protection. From car washes to dairies, the NEMA 4X box is the go-to specification in corrosive situations.
