The document discusses hazardous location classifications according to the National Electric Code (NEC) Article 500. It defines Class and Division systems for classifying locations where hazardous concentrations of flammable gases, vapors, or combustible dust may be present. The classifications are based on the probability and duration of hazardous material concentrations being present, with Class I for gases/vapors, Class II for dusts, and Class III for easily ignitable fibers. The chart outlines the specific divisions and zones within each class based on likelihood and duration of hazardous material presence. Typical hazard materials and applications are listed for each group.

1. HAZARDOUS LOCATION
CLASSIFICATIONS
Class & Division
System Article 500 of the National Electric Code (NEC)
PROBABILITY OF HAZADOUS MATERIAL
IGNITABLE CONCENTRATIONS OF HAZARDS
flammable vapors,
gases & liquids
EASILY IGNITABLE
FIBERS & fLYINGS
COMBUSTIBLE/
flammable DUST
NEC500/NEC505 CHART
CLASS I CLASS II CLASS III
DANGER
FLAMMABLE
DUST
Exists under normal operating
conditions and/or hazard
caused by frequent
maintenance, repair, and
equipment failure
Handled, processed, or used in
closed containers/systems and
escape through accidental
rupture or breakdown
CAUTION
FLAMMABLE
FIBERS OR
FLYINGS
FLAMMABLE
GAS
DIVISION 1 DIVISION 2
CLASS I
GROUP A GROUP B GROUP C GROUP D
DIVISION 1
ZONE 0
ZONE 1
Explosion hazards
present continuously
or occasionally under
normal operating
conditions
CLASS II
DIVISION 1
ZONE 20
ZONE 21
Combustible dust is
present in quantities
sufficient to produce
explosive and
ignitable mixtures
CLASS III
DIVISION 1
NOT
EQUIV.
Easily ignitable
fibers/flyings are
handled or
manufactured
- NEC 501
- NEC 500
- NEC 502
- NEC 500
- NEC 503
- NEC 500
NEC 505 NEC 505 NEC 505
CLASS I
DIVISION 2
ZONE 2
Ignitable
concentrations of
flammable gases or
vapors are not
normally present but
could present in the
case of a fault
CLASS II
DIVISION 2
ZONE 22
Combustible dusts
due to abnormal
operations may be
present in quantities
sufficient to produce
explosive or ignitable
mixtures
CLASS III
DIVISION 2
Easily ignitable
fibers/flyings are
stored or handled
- NEC 501
- NEC 500
- NEC 502
- NEC 500
- NEC 503
- NEC 500
NEC 505 NEC 505
Continually or likely present NOT likely present
GROUP: TYPICAL HAZARD MATERIAL
TYPICAL APPLICATIONS
eXPLOSIVE CHARACTERISTICS OF THE SPECIFIC MATERIALS INVOILVED
GROUP E GROUP F GROUP G
Acetylene Hydrogen
Butadiene
Ethylene Oxide
Propylene Oxide
Ethylene
Cyclopropane
Ethyl Ether
Aluminum
Magnesium
Commercial Alloys
Coal
Carbon Black
Charcoal
Coke Dusts
Flour
Grain
Wood
Plastic
Chemicals
Propane
Acetone
Ammonia
Benzene
Butane
Ethanol
Gasoline
Methanol
Natural Gas
GROUPS
A, B, C, D
GROUPS
E, F, G
GROUPS
A, B, C, D
GROUPS
F, G
GAS
DUST
SOURCES
Chemical Plants
Rifineries
Aerospace Sites
Bulk Loading Stations
Mines
Munitions Storage Areas
Offshore Platforms
Nuclear Facilities
Power Generation Facilities
and more...
Land Based Drilling Rigs
Grain Storage Processing
Coal Handling Storage
Metal Grinding &Working
Pharmaceutical Plants
and more...
Textile
Mattress
Clothing
Cotton Mills
Wool Processing
Wood Cutting/Pulverizing
and more...
CLASS I CLASS II CLASS III
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https://www.macromatic.com/blog/relays/hazardous-location-overview
https://www.guardiantelecom.com/resources/knowledgebase/hazardous-locations/
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