Cut Sheet

V7-T1-360 Volume 7—Logic Control, Operator Interface and Connectivity Solutions CA08100008E—June 2015 www.eaton.com
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1.11
Pushbuttons and Indicating Lights
30.5 mm Class I Division 2 Hazardous Locations—10250T/E34
Ratings
Summary of NEC Article 500
The NEC Article 500 explains
in great detail the
requirements for the
installation of wiring and
electrical equipment in
hazardous locations. The
purpose of this summary is
for general reference only,
the National Electrical Code
along with other applicable
authorities having jurisdiction
over the site should be the
installer’s guidelines when
wiring or installing electrical
equipment in any hazardous
or potentially hazardous
location.
Class I, Division 2 Definition
Class I, Division 2 covers
hazardous locations where
flammable gases, vapors or
volatile liquids are handled
either in a closed system, or
confined within suitable
enclosures, or where
hazardous concentrations are
normally prevented by
positive mechanical
ventilation. Areas adjacent to
Division 1 locations, into
which gases might
occasionally flow, would
also belong to Division 2
(NEC (500.5[b])).
Hazardous Location
Any area where there is the
possibility of explosion and
fire resulting from the
presence of flammable
vapors, liquids or gas, or
combustible dust or fibers.
Summary of NEC Article 505
The NEC also classifies
hazardous locations for
flammable gases and vapors
into zones under NEC 505.
This system is more in line
with the European
Standards, CENELEC and
IEC, with the major
difference being that NEC
505 only classifies gases and
vapors while CENELEC and
IEC also include dusts.
Summary of Classifications
NEC 500–503
NEC 505
Note
For additional information on grouping of compounds, see NFPA 497M-1991 and NFPA 325-1994.
Class Division Group
I. Gas
1. Hazard may exist—May exist in
atmosphere under normal operating
conditions
A. Acetylene
B. Hydrogen and manufactured gases containing 30% hydrogen by
volume (e.g. butadiene, ethylene oxide, propylene oxide)
C. Petrochemicals (e.g. carbon monoxide, ether, ethylene, hydrogen
sulfide, morpholine, cyclopropane)
D. Petrochemicals (e.g. gasoline, benzene, butane, propane, acetone,
ammonia, vinyl chloride)
2. Potential hazard—May be present in
atmosphere only under abnormal
circumstances OR location adjacent to
Class I, Division 1 location
A. Acetylene
B. Hydrogen and manufactured gases containing 30% hydrogen by
volume (e.g. butadiene, ethylene oxide, propylene oxide)
C. Petrochemicals (e.g. carbon monoxide, ether, ethylene, hydrogen
sulfide, morpholine, cyclopropane)
D. Petrochemicals (e.g. gasoline, benzene, butane, propane, acetone,
ammonia, vinyl chloride)
II. Dust 1. Hazard may exist—May exist in
atmosphere under normal operating
conditions
E. Conductive and combustible dust (resistivity <10
5
ohm/cm)
(metal dusts)
F. Carbonaceous dusts (resistivity >10
2
ohms/cm but
<
10
8
ohms/cm) (e.g.
carbon black, coke dust, coal)
G. Non-conductive combustible dust (resistivity
>
10
5
ohms/cm) (e.g. grain
dust, flour, starch, sugar, plastics)
2. Potential hazard—May be present in
atmosphere only under abnormal
circumstances
F. Carbonaceous dusts (resistivity >10
2
ohms/cm but
<
10
8
ohms/cm) (e.g.
carbon black, coke dust, coal)
G. Non-conductive combustible dust (resistivity
>
10
5
ohms/cm) (e.g. grain
dust, flour, starch, sugar, plastics)
III. Fibers 1. Production areas Easily ignitable fibers or flyings
2. Handling and storage areas Easily ignitable fibers or flyings
Class Zone Group
I. Gas
0. Continuously present or present for long
periods of time
IIC. Acetylene, hydrogen or equivalent hazard
IIB. Acetaldehyde, ethylene or equivalent hazard
IIA. Acetone, ammonia, ethyl alcohol, gasoline, methane, propane or
equivalent hazard
IIC. Acetylene, hydrogen or equivalent hazard1. Likely to exist under normal operating or
maintenance conditions or adjacent to
Zone 0
IIB. Acetaldehyde, ethylene or equivalent hazard
IIA. Acetone, ammonia, ethyl alcohol, gasoline, methane, propane or
equivalent hazard
2. Not likely to occur in normal operation
and if they do occur will only exist for
short period or adjacent to Zone 1
IIC. Acetylene, hydrogen or equivalent hazard
IIB. Acetaldehyde, ethylene or equivalent hazard
IIA. Acetone, ammonia, ethyl alcohol, gasoline, methane, propane or
equivalent hazard