Different Lights for Different Hazardous Locations
The National Electric Code (NEC) defines hazardous locations by ‘class’ and ‘division’.
There are 3 classes:
Class I – Locations are made hazardous by the presence of flammable gases, liquids, or vapors. Class II – Locations are made hazardous by the presence of combustible dusts. Class III – Locations contain easily ignitable fibers or flyings.
The ‘Division’ refers to the likelihood that ignitable concentrations of flammable materials are present. There are 2 divisions:
Division 1 designates an environment where ignitable concentrations of flammable gases, liquids, vapors, or dusts can exist some of the time or all of the time under normal operating conditions or where easily ignitable fibers and flyings are manufactured, handled, or used.
Division 2 locations are where ignitable concentrations are not likely to exist under normal operating conditions or where Class 3 materials are stored or handled.
Hazardous classes are further defined by ‘groups’ based on the physical properties of their combustible materials:
Group A – Acetylene
Group B – Hydrogen
Group C – Ethylene, Carbon Monoxide
Group D – Propane, Gasoline, Naphtha, Benzene, Butane, Ethyl Alcohol, Acetone, Methane
Group E – metals including Aluminum, Magnesium (Div. 1 only)
Group F – Carbonaceous dusts including coal, Carbon Black, Coke
Group G – Dusts not included in E and F including wood, plastics, flour, starch, or grain dusts.