1.1 This Standard contains the specific requirements for the construction and testing of electrical apparatus with type of protection flameproof enclosure "d", intended for use in potentially explosive atmospheres. 1.2 This Standard supplements EN 50014, the requirements of which apply to electrical apparatus with flameproof enclosure. 1.3 This Standard covers only Category M2 and Category 2. 1.4 Due to the safety factors incorporated in the type of protection "d" the uncertainty of measurement inherent in good quality, regularly calibrated measurement equipment is considered to have no significant detrimental effect and need not to be taken into account when making any measurements necessary to verify the compliance of the enclosure with the requirements of this standard.