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Electrical Enclosures
Enclosures do not normally protect devices against conditions such
as condensation, icing, corrosion or contamination, which may occur
within the enclosure or enter via the conduit or unsealed openings.
Users must make adequate provisions to safeguard against such conditions,
and satisfy themselves that the equipment is properly protected.
For definitions, descriptions and test criteria see National Electrical
Manufacturers Association (NEMA) Standards Publications No. 250-1979.
See specific enclosure type for more detail.
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NEMA 12
Type 12 enclosures are intended for indoor use primarily to provide
a degree of protection against dust, falling dirt, and dripping
non-corrosive liquids. They are designed to meet drip, dust and
rust-resistant tests. They are not intended to provide protection
against conditions such as internal condensation.
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NEMA 4
Type 4 enclosures are intended for indoor or outdoor use primarily
to provide a degree of protection against windblown dust and rain,
splashing water, and hose-directed water. They are designed to meet
hose down, dust, external icing, and rust-resistance design tests.
They are not intended to provide protection against conditions such
as internal condensation or internal icing. Enclosures are made
of heavy gauge stainless steel, cast aluminum or heavy gauge sheet
steel, depending on the type of unit and size. Cover has synthetic
rubber gasket. |
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NEMA 4x
Non-metallic, corrosion-resistant fiberglass reinforced polyester
or stainless steel.
Type 4x enclosures are intended for indoor or outdoor use primarily
to provide a degree of protection against corrosion, windblown
dust and rain, splashing water, and hose-directed water. They
are designed to meet the hose-down, dust, external icing and corrosion-resistance
design tests. They are not intended to provide protection against
conditions such as internal condensation or internal icing.
Enclosure is fiberglass-reinforced polyester with a synthetic
rubber gasket between cover and base. Ideal for industries as
chemical plants and paper mills.
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NEMA 7
For hazardous gas locations (bolted enclosure)
Type 7 enclosures are for indoor use in locations classified as
Class 1, Groups C or D, as defined in the National Electrical Code.
Type 7 enclosures are designed to be capable of withstanding the
pressures resulting from an internal explosion of specified gases,
and contain such an explosion sufficiently that an explosive gas-air
mixture existing in the atmosphere surrounding the enclosure will
not be ignited.
Enclosed heat generating devices are designed not to cause external
surfaces to reach temperatures capable of igniting explosive gas-air
mixtures in the surrounding atmosphere. Enclosures are designed
to meet explosion, hydrostatic and temperature design tests. Finish
is a special corrosion-resistant gray enamel. |
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