This Standard specifies the dimensional and test requirements for flameproof restrained plugs and receptacles, incorporating three power contacts, one pilot contact and possibly one or more auxiliary contact, a scraping earth contact and an earthed phase barrier, intended for use with restricted earth-fault systems in coal mines. Provision is also made for restrained coupling units which enable lengths of trailing cable to be coupled together.Restrained plugs and receptacles to this Standard are not intended to be coupled or uncoupled while the circuit is energized.The Standard prescribes the dimensions necessary to provide for the interconnection of restrained plugs and receptacles of different makes; it also deals with some electrical and mechanical requirements including the provision of earthed phase barriers for protection against interphase faults. It does not, however, purport to specify a fully detailed design.The Standard provides for plug and receptacle discrimination, i.e. an arrangement whereby plugs and receptacles of different rated voltages are physically prevented from engagement.NOTES:1 The term 'receptacle' as used in this Standard is synonymous with the term 'socket-outlet' in AS 3000. The term 'receptacle' has been chosen to avoid confusion with the individual sockets within the plug.2 Appendix A lists information which should be supplied by a user with any enquiry or order.3 A typical plug and receptacle assembly is shown in Figure 1.1 and a typical plug coupling unit is shown in Figure 1.2.