Specifies the particular requirements for construction, test and marking for electrical apparatus of Group II intended for use in Zone 0. This electrical apparatus, within the operational parameters specified by the manufacturer, ensures a very high level of protection that includes rare faults related to the apparatus or two faults occurring independently of each other. It is intended for use in Zone 0 hazardous areas, in which explosive gas atmospheres caused by mixtures of air and gases, vapours or mists under normal atmospheric conditions are present continuously, for long periods or frequently.