Enclosure NEMA Rating Guide
NEMA Ratings Guide for Enclosures
What are NEMA ratings?
A rating system from National Electrical Manufacturers Association that defines the types of environments in which an electrical enclosure can be used. When deciding which enclosure to use, the NEMA rating is critical to ensure protection of the equipment inside. All NEMA rated enclosure provide a degree of protection to personnel against incidental contact from the enclosed equipment.
The first criteria would normally be indoor or outdoor. If it is going to be used outdoors, you will not want to use a NEMA 1 or 12 enclosure because they are rated for indoor use only. The result could be damage to the components inside the enclosure. Outdoor enclosures can be used for indoor applications with the only real downside being cost as outdoor enclosures are normally more expensive.
The most common enclosures manufactured are in compliance with the following NEMA ratings. NEMA 1 and 12 for indoor use only. NEMA 3R,4 and 4X for outdoor or indoor use. Below is a listing of the NEMA ratings with a simplified explanation of the rating, followed by a matrix of the rating and conditions, and finally at the bottom we list the actual NEMA code.
NEMA Rating Simplified Version
INDOOR
NEMA 1- Indoor use, degree of protection from falling dirt.
NEMA 2- Indoor use, degree of protection from falling dirt and falling water.
NEMA 5- Indoor use, degree of protection from falling dirt, falling dust, fibers, lint, and
flyings, falling water and light splashing.
NEMA 12- Indoor use, degree of protection from falling dirt, circulating dust, fibers, lint, and
flyings, falling water and light splashing.
NEMA 13- Indoor use, degree of protection from falling dirt, circulating dust, fibers, lint, and
flyings, spraying, splashing, and seepage of water, oil & non-corrosive liquids.
OUTDOOR
NEMA 3- Indoor or outdoor use, degree of protection from windblown dust, falling dirt, rain,
snow, and sleet, not damaged from external formation of ice.
NEMA 3R- Indoor or outdoor use, degree of protection from falling dirt, snow, and sleet, not
damaged from external formation of ice.
NEMA 3S- Indoor or outdoor use, degree of protection from falling dirt, snow, and sleet, remain
operable when ice laden.
NEMA 4- Indoor or outdoor use, degree of protection from windblown dust, falling dirt, rain,
snow, and sleet, splashing water, hose directed water, not damaged from external
formation of ice.
NEMA 4X- Indoor or outdoor use, degree of protection from windblown dust, falling dirt, rain,
snow, and sleet, splashing water, hose directed water, and corrosion, not damaged
from external formation of ice.
NEMA 6- Indoor or outdoor use, degree of protection from windblown dust, falling dirt, rain,
snow, and sleet, splashing water, hose directed water, occasional temporary
submersion at limited depth, not damaged from external formation of ice.
NEMA 6P- Indoor or outdoor use, degree of protection from windblown dust, falling dirt, rain,
snow, and sleet, splashing water, hose directed water, prolonged submersion at
limited depth, level of corrosion, not damaged from external formation of ice.
HAZARDOUS LOCATIONS
NEMA 7- Indoor use, Hazardous Locations Class 1 Division 1, Groups A, B, C, D.
(Contains an internal explosion without causing an external hazard)
NEMA 8- Indoor or outdoor use, Hazardous Locations Class 1 Division 1, Groups A, B, C, D.
(Prevents combustion through the use of oil-immersed equipment)
NEMA 9- Indoor use, Hazardous Locations Class 2 Division 1, Groups E, F, G.
(Prevents the ignition of combustible dust)
NEMA 10- Indoor or outdoor use, Mine Safety and Health Administration. 30 CFR Part 18.
(Contains an internal explosion without causing an external hazard)
NEMA Standards Code (Non-Hazardous Locations)
In Non-Hazardous Locations, the specific enclosure Types, their applications, and the environmental conditions they are designed to protect against, when completely and properly installed, are as follows:
Type 1: Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts and to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt).
Type 2: Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); and to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing).
Type 3: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.
Type 3R: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.
Type 3S: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and for which the external mechanism(s) remain operable when ice laden.
Type 3X: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); that provides an additional level of protection against corrosion and that will be undamaged by the external formation of ice on the enclosure.
Type 3RX: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); that will be undamaged by the external formation of ice on the enclosure that provides an additional level of protection against corrosion; and that will be undamaged by the external formation of ice on the enclosure.
Type 3SX: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); that provides an additional level of protection against corrosion; and for which the external mechanism(s) remain operable when ice laden.
Type 4: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow, splashing water, and hose directed water); and that will be undamaged by the external formation of ice on the enclosure.
Type 4X: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow, splashing water, and hose directed water); that provides an additional level of protection against corrosion; and that will be undamaged by the external formation of ice on the enclosure.
Type 5: Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and settling airborne dust, lint, fibers, and flyings); and to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing).
Type 6: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (hose directed water and the entry of water during occasional temporary submersion at a limited depth); and that will be undamaged by the external formation of ice on the enclosure.
Type 6P: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (hose directed water and the entry of water during prolonged submersion at a limited depth); that provides an additional level of protection against corrosion and that will be undamaged by the external formation of ice on the enclosure.
Type 12: Enclosures constructed (without knockouts) for indoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and circulating dust, lint, fibers, and flyings); and to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing).
Type 12K: Enclosures constructed (with knockouts) for indoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and circulating dust, lint, fibers, and flyings); and to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing).
NEMA Standards Code(Hazardous Locations)
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.