NEMA Enclosure Rating System

[Paul W. Abernathy]

Hey Guys,

Figured some of you may find this helpful. I have seen some questions regarding enclosures and their ratings so I found this and figured it would help someone out someday.....No I did not write it.....tehehehe..Enjoy!


NEMA RATING FOR ENCLOSURES
NEMA and other organizations have established standards of enclosure construction for control equipment. In general, equipment would be enclosed for one or more of the following reasons:

1. Prevent accidental contact with live parts.
2. Protect the control from harmful environmental conditions.
3. Prevent explosion or fires which might result from the electrical arc caused by the control.

Common types of enclosures per NEMA classification numbers are:

NEMA I - GENERAL PURPOSE
The general purpose enclosure is intended primarily to prevent accidental contact with the enclosed apparatus. It is suitable for general purpose applications indoors where it is not exposed to unusual service conditions. A NEMA I enclosure serves as protection against dust and light indirect splashing, but is not dusttight.
NEMA 3 - DUSTTIGHT, RAINTIGHT
This enclosure is intended to provide suitable protection against specified weather hazards. A NEMA 3 enclosure is suitable for application outdoors, on ship docks, canal and construction work, and for application in subways and tunnels. It is also sleet-resistant.
NEMA 3R - RAINPROOF, SLEET RESISTANT
This enclosure protects against interference in operation of the contained equipment due to rain, and resists damage from exposure to sleet. It is designed with conduit hubs and external mounting, as well as drainage provisions.
NEMA 4 - WATERTIGHT
A watertight enclosure is designed to meet the hose test described in the following note: "Enclosures shall be tested by subjection to a stream of water. A hose with a one inch nozzle shall be used and shall deliver at least 65 gallons per minute. The water shall be directed on the enclosure from a distance of not less than 10 feet and for a period of five minutes. During this period it may be directed in any one or more directions as desired. There shall be no leakage of water into the enclosure under these conditions."
A NEMA 4 enclosure is suitable for applications outdoors on ship docks and in dairies, breweries, etc.
NEMA 4X - WATERTIGHT, CORROSION-RESISTANT
These enclosures are generally constructed along the lines of NEMA 4 enclosures except they are made of a material that is highly resistant to corrosion. For this reason, they are ideal in applications such as paper mills, meat packing, fertilizer and chemical plants where contaminants would ordinarily destroy a steel enclosure over a period of time.
NEMA 5 – Enclosures constructed for indoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt; against settling airborne dust, lint, fibers, and flyings; and to provide a degree of protection against dripping and light splashing of liquids.
NEMA 6 – Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt; against 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.
NEMA 6P – Same as NEMA 6 including protection against the entry of water during prolonged submersion at a limited depth.
NEMA 7 - HAZARDOUS LOCATIONS - CLASS I
These enclosures are designed to meet the application requirements of the National Electrical Code for Class I hazardous locations. In this type of equipment, the circuit interruption occurs in air.
"Class I locations are those in which flammable gases or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures."
NEMA 9 HAZARDOUS LOCATIONS - CLASS II
These enclosures are designed to meet the application requirements of the National Electrical Code for Class II hazardous locations.
"Class II locations are those which are hazardous because of the presence of combustible dust."
The letter or letters following the type number indicates the particular group or groups of hazardous locations (as defined in the National Electrical Code) for which the enclosure is designed. The designation is incomplete without a suffix letter or letters.
NEMA 12 - INDUSTRIAL USE
The NEMA 12 enclosure is designed for use in those industries where it is desired to exclude such materials as dust, lint, fibers and flyings, oil see page or coolant see page. There are no conduit openings or knockouts in the enclosure, and mounting is by means of flanges or mounting feet.
NEMA 13 - OILTIGHT, DUSTTIGHT NEMA 13 enclosures are generally of cast construction, gasketed to permit use in the same environments as NEMA 12 devices. The essential difference is that, due to its cast housing, a conduit entry is provided as an integral part of the NEMA 13 enclosure, and mounting is by means of blind holes, rather than mounting brackets.

5 and 6 added..Thanks to GREG.....

[Greg Fretwell]

They left out NEMA 5 and NEMA 6 (a pool light)

NEMA 5 – Enclosures constructed for indoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt; against settling airborne dust, lint, fibers, and flyings; and to provide a degree of protection against dripping and light splashing of liquids.

NEMA 6 – Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt; against 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.

NEMA 6P – Same as NEMA 6 including protection against the entry of water during prolonged submersion at a limited depth.

[Paul W. Abernathy]

AWESOME...............LOVE IT..Great job Greg

I added them to the original.....

[Paul W. Abernathy]

Bump...nice to have for the newbies as reference.