1.1 This European Standard specifies the requirements for the design and construction of non-electrical equipment, intended for use in potentially explosive atmospheres, protected by the type of protection Constructional Safety 'c'. 1.2 This European Standard supplements the requirements in EN 13463-1, the contents of which also apply in full to equipment constructed in accordance with this European Standard. 1.3 The type of ignition protection described in the standard can be used either on its own or in combination with other types of ignition protection to meet the requirements for equipment of Group I, category M2 or Group II, categories 1 and 2 depending on the ignition hazard assessment in EN 13463-1. Type of ignition protection 'c' is not applicable for Group I for M1. These requirements are specified in EN 50303. NOTE Most category 3 equipment, only needs to meet the requirements of EN 13463-1, but some category 3 equipment may have to meet the requirements of this European Standard for some of the ignition sources identified in the ignition hazard assessment.