This part of IEC 60079 specifies requirements for construction, test and marking for Ex Equipment that contains parts of the equipment with different Explosion Protection Levels (EPLs) and a separation element. This equipment is mounted across a boundary where different EPLs are required, e.g. between different gas hazardous areas, dust hazardous areas or gas hazardous areas adjacent to dust hazardous areas. EXAMPLE: Equipment installed in the wall of a storage vessel containing Zone 0 (requiring EPL Ga) inside an area defined as Zone 1 (requiring EPL Gb). Separation elements are considered for both electrical and non-electrical equipment. If mechanical energy may be transformed into a potential ignition source, additionally an ignition hazard assessment in accordance with ISO 80079-36 is performed and appropriate measures are undertaken. Suitable measures are provided in ISO 80079-37 and/or in IEC TS 60079-42. This standard also specifies requirements for the combination of two EPL Gb Types of Protection to form an EPL Ga Type of Protection. Examples are included in 4.2. This standard supplements and modifies the general requirements of IEC 60079-0. Where a requirement of this standard conflicts with a requirement of IEC 60079-0, the requirement of this standard takes precedence.