Class I, Division 1 location is a location:
NOTE: This classification usually includes locations where volatile flammable liquids or liquefied flammable gases are transferred from one container to another; interiors of spray booths and areas in the vicinity of spraying and painting operations where volatile flammable solvents are used; locations containing open tanks or vats of volatile flammable liquids; drying rooms or compartments for the evaporation of flammable solvents; inadequately ventilated pump rooms for flammable gas or volatile flammable liquids; and all other locations where ignitable concentrations of flammable vapors or gases are likely to occur in the course of normal operations.
Class I, Division 2 location is a location:
NOTE: This classification usually includes locations where volatile flammable liquids or flammable gases or vapors are used, but which would become hazardous only in case of an accident or of some unusual operating condition. The quantity of flammable material that might escape in case of an accident, the adequacy of ventilating equipment, the total area involved, and the record of the industry or business with respect to explosions or fires are all factors that merit consideration in determining the classification and extent of each location.
Piping without valves, checks, meters, and similar devices would not ordinarily introduce a hazardous condition even though used for flammable liquids or gases. Locations used for storage of flammable liquids or of liquefied or compressed gases in sealed containers would not normally be considered hazardous unless subject to other hazardous conditions.
Electrical conduits and their associated enclosures separated from process fluids by a single seal barrier are classed as a Division 2 location if the outside of the conduit and enclosures is a nonhazardous location.
NEC Division System Gas & Dust Groups
|Class I, Division 1 & 2||A||Acetylene|
|Class II, Division 1 & 2||E (Division 1 only)||Metal dusts, such as magnesium (Division 1 only)|
|F||Carbonaceous dusts, such as carbon and charcoal|
|G||Non-conductive dusts, such as flour, grain, wood, plastic|
|Class II, Division 1 & 2||Ignitable fibers/flyings, such as cotton, lint, rayon|
NEC & IEC Zone System Gas & Dust Groups
|Zone 0, 1 & 2||IIC||Acetylene & Hydrogen
(equivalent to NEC Class I, Groups A and B)
|IIB + H2||Hydrogen
(equivalent to NEC Class I, Group B)
(equivalent to NEC Class I, Group C)
(equivalent to NEC Class I, Group D)