UFC 3 -520-01
June 10, 2002
Table 8-4. Indoor Hazardous Applications
Type of Enclosure
Protection Provided For:
NEMA 7 and 8
NEMA 9
Class
A
B
C
D
E
F
G
Acetylene
I
x
Hydrogen, manufactured gas
I
x
x
Ethyl ether, ethylene,
I
x
x
x
cyclopropane
Gasoline, jet fuel, hexane,
I
x
x
x
x
butane, naphtha, propane,
acetone, toluene, isoprene
Metal dust
II
x
x
x
x
x
Carbon black, coal dust, coke
II
x
x
x
x
x
dust
Flour, starch, grain dust
II
x
x
x
x
x
x
x
Fibers, flyings
III
x
x
x
x
x
x
X
Note: Refer to NEC Article 500.4 (2002 Edition) for information regarding hazardous
substances not listed in this table.
8-2.4
Evaluate the enclosure temperature rise and determine if special cooling
options will be required to dissipate the generated heat. Enclos ure manufacturers can
provide application guidance to assist in the selection and sizing of cooling options.
8-3
HAZARDOUS LOCATIONS.
8-3.1
NEC Article 500 (2002 Edition) establishes hazardous location classifications
based on the flammable vapors, liqui ds, or gases, or combustible dusts or fibers that
might be present. The classification also considers the likelihood that a flammable or
combustible concentration or quantity is present. Electrical design criteria are based on
the specific location classification. Table 8 -5 lists the various hazardous location
classifications; refer to NEC Article 500 (2002 Edition) for the definition of each location.
8-8
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