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NEMA
Enclosure Ratings
National Electrical Manufacturer's Association (NEMA)
standard #250 designates the degree of protection provided by electrical
enclosures. The G-Series
Heavy-Duty Foot Switches are certified to NEMA enclosure types 2, 4, and 13. The following NEMA definitions describe these enclosure
ratings.
Definitions (from NEMA 250-2003):
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 2 - 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, and to provide a degree of protection against dripping and light
splashing of liquids.
Type 4 - 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, rain, sleet, snow, windblown dust,
splashing water, and hose-directed water; and that will be undamaged by
the external formation of ice on the enclosure.
Type 13 - 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 circulating dust, lint, fibers, and filings; and
against the spraying, splashing, and seepage of water, oil, and
non-corrosive coolants.
IEC 60529 - Degree of Protection Provided by Enclosures (IP Ratings)
The ability of an enclosure to protect a device from
outside elements (such as rain, or to keep fingers away from electrical
circuits) is often specified by "IP" ratings (standing for
"ingress protection"), which are specified by European
Standard IEC 60529. This European standard is often
used or referenced in the United States when evaluating enclosures.
Naturally, higher degrees of protection can
increase the cost of a product, and should be applied only when necessary
to ensure safe and functional operation of the product in the
environmental conditions and application in which it will be used. Refer to the appropriate
sections of IEC 60529 for complete information on the
standard. The
following is a brief summary of the IP rating system.
The first digit of the IP designation describes
the degree of protection against access to hazardous parts.
The second digit designates the
degree of protection against water.
The third digit describes the degree of
protection against mechanical impact, and is often not
specified. Example:
A rating of IP-21 indicates that the enclosure offers protection from
objects greater than 12-mm in diameter, such as a typical person's finger
or a metal rod (indicated by the first digit being "2"), and protection
from water dripping vertically onto the unit without the unit becoming
electrically unstable or unsafe through shorting or other loss of
insulation effectiveness (indicated by the second digit being "1").
The third digit is often not specified.
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1st
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Protection against foreign objects
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2nd
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Protection against water
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3rd
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Protection against mechanical
impacts
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0
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Not protected
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0
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Not protected
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0
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Not protected
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1
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Protected against objects greater
than 50 mm diameter
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1
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Protected against water dripping
vertically onto the unit
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1
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Impact 0.225 joule
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2
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Protected against objects greater
than 12 mm diameter
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2
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Protected against dripping water when
tilted up to 15 degrees
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2
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Impact 0.375 joule
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3
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Protected against objects greater
than 2.5 mm diameter
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3
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Protected against spraying water
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3
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Impact 0.60 joule
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4
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Protected against objects greater
than 1.0 mm diameter
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4
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Protected against splashing water
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n/a
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5
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Dust protected
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5
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Protected against water jets
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5
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Impact 2.00 joule
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6
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Dust tight
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6
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Protected against heavy seas
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n/a
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-----
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n/a
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7
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Protection against the effects of
immersion
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7
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Impact 6.00 joule
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n/a
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8
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Protection against submersion
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n/a
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n/a
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n/a
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9
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Impact 20.00 joule
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