Comparing Classes/Divisions with Zones – Safety Engineering (SAFTENG)

The US still uses the Class and Division system to classify electrical systems in hazardous locations. However, outside the US, the Zone system is more widely used. Manufacturers are beginning to list their equipment based on the Zone(s) it is rated for, which can cause translation confusion. The table below may be of help.

Zone 0	Zone 1	Zone 2
Where ignitable concentrations of flammable gases, vapors, or liquids are present continuously or for long periods of time under normal operating conditions.	Where ignitable concentrations of flammable gases, vapors, or liquids: Are likely to exist under normal operating conditions  May exist frequently because of repair, maintenance operations, or leakage	Where ignitable concentrations of flammable gases, vapors, or liquids: Are not likely to exist under normal operating conditions Occur for only a short period of time Become hazardous only in case of an accident or some unusual operating condition
Division 1		Division 2
Where ignitable concentrations of flammable gases, vapors, or liquids: Are likely to exist under normal operating conditions Exist frequently because of maintenance/repair work or frequent equipment failure		Where ignitable concentrations of flammable gases, vapors, or liquids: Are not likely to exist under normal operating conditions Are normally in closed containers where the hazard can only escape through accidental rupture or breakdown of such containers or in case of abnormal operation of equipment

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