Class Hazardous Locations Defined |
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This chart was taken from an OSHA document entitled Hazardous Class Locations. For a more detailed explaination of Classes, Divisions and Groups visit their website or http://www.osha.gov/doc/outreachtraining/htmlfiles/hazloc.html.
| Summary of Class I, II, III Hazardous Locations |
| CLASSES |
GROUPS |
DIVISIONS |
| 1 |
2 |
I Gases, vapors, and liquids
(Art. 501) |
A: Acetylene
B: Hydrogen, etc.
C: Ether, etc.
D: Hydrocarbons, fuels, solvents, etc. |
Normally explosive and hazardous |
Not normally present in an explosive concentration (but may accidentally exist) |
II Dusts
(Art. 502) |
E: Metal dusts (conductive,*and explosive)
F: Carbon dusts (some are conductive,* and all are explosive)
G: Flour, starch, grain, combustible plastic or chemical dust (explosive) |
Ignitable quantities of dust normally are or may be in suspension, or conductive dust may be present |
Dust not normally suspended in an ignitable concentration (but may accidentally exist). Dust layers are present. |
III Fibers and flyings
(Art. 503) |
Textiles, wood-working, etc. (easily ignitable, but not likely to be explosive) |
Handled or used in manufacturing |
Stored or handled in storage (exclusive of manufacturing) |
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Combustible Dust Resources 
