Area and Material Classification

The design of electrical equipment and instrumentation is based on the nature of the process hazards or specific process classifications. The classification method is defined in the National Electrical Code it is a function of the nature and degree of the process hazards within a particular area. The rating method includes Classes I, II, and III, Groups A-G, and Divisions 

Class I Locations where flammable gases or vapors are present. 

Class III Hazard locations where combustible fibers or dusts are present but not likely to be in suspension. 

The groups designate the presence of specific chemical types. Chemicals that are grouped have equivalent hazards  

11NFPA 70, The National Electrical Code Handbook (Quincy, MA National Fire Protection Association, 

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