Safety Ratings Explanation
Understanding Standards:
UL/CSA – Recognized in the USA and Canada
ATEX – Recognized by EU Member Nations
IECEx – Recognized by member nations; see list at www.iecex.com/information/countries/
UNDERSTANDING INTRINSIC SAFETY RATINGS:
Intrinsic safety is a protection technique for the safe operation of electrical equipment by
limiting electrical and thermal energy available for ignition in hazardous areas.
UNDERSTANDING Classes:
The National Electric Code (NEC) defines hazardous locations by “Class” & “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 because combustible dusts are present.
CLASS III
locations contain easily
ignitable fibers or flyings.
UNDERSTANDING Groups:
Hazardous classes are further defined by “groups” based on the physical properties of their combustible
materials. There groups include:
Group A Acetylene
Group B Hydrogen
Group C Ethylene, and carbon monoxide
Group D Propane, gasoline, naphtha, benezene,
butane, ethyl alcohol, acetone, and methane
Group E Metals including aluminum, and magnesium (Div. 1 only)
Group F Carbonaceous dusts including coal, carbon black, and coke
Group G Dusts not included in E and F including wood, plastics, flour, starch, and grain dusts
Understanding Divisions:
The “division” designation refers to the likelihood that ignitable concentrations of flammable materials
are present. There are two divisions:
Division 1/ Zone 0
designates an environment where ignitable concentrations of flammable gases, liquids, vapors, or dust 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 / Zone 1-2
locations are where ignitable concentrations
are not likely to exist under normal operating
conditions or where Class 3 materials are stored
or handled.