Electrical apparatus should be selected for use in hazardous area in accordance with each of the following criteria:-
a) The type of protection of the apparatus in relation to the area classification of the hazardous area.
b) The temperature classification of the apparatus in relation to the ignition temperature of the gases and vapors involved.
c) The apparatus gas group (where applicable) in relation to the relevant properties of the gases and vapors involved.
d) The apparatus construction and enclosure in relation to the environmental conditions.