Guide for Hazardous Areas

Hazardous areas according to ATEX and IECEx Zones
Hazardous areas according to North American classes and divisions
Zones - define the type of explosive atmosphere as well as the likelihood of an explosive atmosphere being present 
0 - Explosive gas atmosphere present continuously or for long periods 
1 - Explosive gas atmosphere likely to occur in normal operation 
2 - Explosive gas atmosphere not likely to occur in normal operation but may be present for short periods 
20 - Explosive dust atmosphere present continuously or for long periods 
21 - Explosive dust atmosphere likely to occur in normal operation 
22 - Explosive dust atmosphere not likely to occur in normal operation but may be present for short periods


Classes - define the type of explosive atmosphere 
I - A location made hazardous by the presence of flammable gas or vapour that may be present in the air in quantities sufficient to produce an explosive or ignitable mixture
II - A location made hazardous by the presence of combustible or electrically conductive dust
III - A location made hazardous by the presence of easily ignitable fibers or flyings in the air, but not likely to be in suspension in quantities sufficient to produce ignitable mixtures
Divisions - define the likelihood of an explosive atmosphere being present
1 - A location where a classified hazard exists or is likely to exist under normal conditions
2 - A location where a classified hazard does not normally but is possible to appear under abnormal conditions
In Canada new installation must now use the Class / Zone system of Zones instead of Divisions. Existing installations may use either system.
In the USA, all installations can use either the Class / Division or the Class / Zone system.

ATEX equipment group ATEX equipment category and environment type Zone classification ATEX / IECEx Required equipment protection level (EPL) Class / Zone classification US / Canada Class / Division classification US / Canada
I M1 N/A Ma N/A Mining
M2 Mb
II 1G Zone 0 Ga Class 1, Zone 0 Class I, Division 1
2G Zone 1 Gb Class 1, Zone 1
3G Zone 2 Gc Class 1, Zone 2 Class I, Division 2
1D Zone 20 Da Class 1, Zone 20 Class II, Division 1
2D Zone 21 Db Class 11, Zone 21
3D Zone 22 Dc Class 11, Zone 22 Class II, Division 2, Class III