NEMA Enclosure Types

NEMA Enclosure Types
Table 2
[From NEMA 250-2003]
Comparison of Specific Applications of Enclosures
for Outdoor Nonhazardous Locations
Type of Enclosure
Provides a Degree of Protection Against
the Following Conditions
3 3X 3R* 3RX* 3S 3SX 4 4X 6 6P
Access to hazardous parts X X X X X X X X X X
Ingress of water (Rain, snow, and sleet **)
X X X X X X X X X X
Sleet ***
... ... ... ... X X ... ... ... ...
Ingress of solid foreign objects (Windblown
dust, lint, fibers, and flyings)
X X ... ... X X X X X X
Ingress of water (Hosedown) ... ... ... ... ... ... X X X X
Corrosive agents ... X ... X ... X ... X ... X
Ingress of water (Occasional temporary
submersion)
... ... ... ... ... ... ... ... X X
Ingress of water (Occasional prolonged
submersion)
... ... ... ... ... ... ... ... ... X
* These enclosures may be ventilated.
** External operating mechanisms are not required to be operable when the enclosure is ice covered.
*** External operating mechanisms are operable when the enclosure is ice covered.
In
Hazardous Locations, when completely and properly installed and maintained,
Type 7 and 10 enclosures are designed to contain an internal explosion without causing
an external hazard. Type 8 enclosures are designed to prevent combustion through the
use of oil-immersed equipment. Type 9 enclosures are designed to prevent the ignition
of combustible dust.
Type 7 Enclosures constructed for indoor use in hazardous (classified) locations
classified as Class I, Division 1, Groups A, B, C, or D as defined in NFPA 70.
Type 8 Enclosures constructed for either indoor or outdoor use in hazardous
(classified) locations classified as Class I, Division 1, Groups A, B, C, and D as defined
in NFPA 70.
Type 9 Enclosures constructed for indoor use in hazardous (classified) locations
classified as Class II, Division 1, Groups E, F, or G as defined in NFPA 70.
Type 10 Enclosures constructed to meet the requirements of the Mine Safety and
Health Administration, 30 CFR, Part 18.
National Electrical Manufacturers Association Approved by NEMA Enclosures Section
1300 N. 17
th
Street, Suite 1752 November 2005
Rosslyn, VA 22209