When you make use of electrical equipment in, around or near any atmosphere having flammable vapors or gases, combustible dusts, flammable liquids, ignitable fibers or flying, there would always be a risk of fire or explosion occurring. These areas where there would be chances of explosion or fire occurring due to an explosive atmosphere and blend would come under the hazardous area classification.
Presently, there have been two kinds of systems used for identifying the hazardous areas, namely the class or division system and the zone system. The class or division system has been used predominantly in the US and Canada. On the other hand, the zone system would be used worldwide.