ANSI/NFPA Areas Description
Class I, Div. 1 - Where ignitable concentrations of flammable gases, vapors or liquids are present continuously or frequently within the atmosphere under normal operation conditions.
Class I, Div. 2 - Where ignitable concentrations of flammable gases, vapors, or liquids are present within the atmosphere under abnormal operating conditions.
Class II, Div. 1 - Where ignitable concentrations of combustible dusts are present within the atmosphere under normal operation conditions.
Class II, Div. 2 - Where ignitable concentrations of combustible dust are present within the atmosphere under abnormal operating conditions.
Class III, Div. 1 - Where easily ignitable fibers or materials producing combustible flyings are present within the atmosphere under normal operation conditions.
Class III, Div. 2 - Where easily ignitable fibers or materials producing combustible flyings are present within the atmosphere under abnormal operating conditions.
Common Materials within Associated Class & Group Ratings, such as "Class I, Division 1, Group A":
Class I Areas: Group A: Acetylene / Group B: Hydrogen / Group C: Propane and Ethylene / Group D: Benzene, Butane, Methane & Propane
Class II Areas: Group E: Metal Dust / Group F: Carbon & Charcoal / Group G: Flour, Starch, Wood & Plastic
Class III Areas: NO GROUP: Cotton & Sawdust
For more information see Article 500 of NFPA 70 - The National Electric Code, as published by the National Fire Protection Association.
Read more about this topic: Electrical Equipment In Hazardous Areas
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