Hazardous Area Classification System

(NEC article 500 through 503/CEC section 18)
Sample Marking

Hazardous Locations are classified by the likelihood of an ignitable concentration of combustible material being present. There are two systems in place, including the traditional North American Division system as well as the alternative Zone system. See below for further details:

Division 1 – Ignitable concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors can exist under normal operating conditions.

Division 2 – Ignitable concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors are not likely to exist under normal operating conditions.

 

Materials are divided by type:

Class I –  Flammable gases, flammable liquid-produced vapors, and combustible liquid-produced vapors. This luminaire can be used as a spot light, down light, tunnel light, or strip light which can provide general illumination in hazardous locations, such as:

Examples Areas:

  • Petroleum refineries, and gasoline storage and dispensing areas
  • Dry cleaning plans where vapors from cleaning fluids can be present
  • Spray finishing areas
  • Aircraft hangars and fuel servicing areas
  • Utility gas plants, and operations involving storage and handling of liquefied petroleum gas or natural gas

 

Class II – Combustible dusts that may combine continuously, periodically, or due to malfunction or failures.

Examples Areas:

  • Grain elevators
  • Flour and feed mills
  • Plants that manufacture, use or store magnesium or aluminum powders
  • Producers of plastics, medicines and fireworks
  • Producers of starch or candies

 

Class III – Ignitable fibers/flyings. Typically these fibers and flyings are not suspended in the air, but can collect around machinery or on lighting fixtures and where heat, a spark or hot metal can ignite them.

Examples Areas:

  • Textile mills, cotton gins. Cotton seed mills, flax processing plants
  • Plants that shape, pulverize or cut wood and create sawdust or flyings

 

Materials are further divided into Groups for Class I, Divisions 1 and 2:

A – Acetylene

B – Hydrogen

C – Ethylene

D – Propane

Materials are further divided into Groups for Class II, Division 1 and 2:

E – Metal Dusts (Div. 1 only)

F – Carbonaceous Dusts

G – Non-Conductive Dusts (flour, grain, wood, plastic, etc.)

There are no groups for Class 3.

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