This Standard specifies the design and test requirements for explosion-protected threephase restrained plugs and receptacles incorporating three power contacts, one pilot contact and possibly one or more auxiliary contacts, an earth contact and an earthed phase barrier intended for use with restricted earth-fault systems in mines and quarries with a working voltage up to and including 3.3 kV. Provision is also made for restrained back-to-back receptacles, which enable lengths of cable to be coupled together.

Restrained plugs and receptacles constructed to this Standard are not intended to be coupled or uncoupled while the circuit is energized.

The Standard covers two types of restrained plugs and receptacles:

(a) Type A

Designed according to Figures in this Standard that prescribe the dimensions necessary to interconnect plugs or receptacles from different manufacturers.

(b) Type B

Designed to dimensions that are not compatible with Type A plugs or receptacles. Type B plugs or receptacles cannot be plugged into or accept a Type A plug or receptacle under normal operation.

Type B plugs and receptacles do not comply with Figures 4.1 to 4.16 but comply with all other requirements of this Standard. Where there is a variation to a particular clause for Type B plugs and receptacles it is specifically stated. The use of transition devices between Type A and Type B systems is permitted.

This Standard also deals with some electrical and mechanical requirements, including the provision of earthed phase barriers to protect against interphase faults. It does not specify fully detailed designs.

This Standard provides for plug and receptacle discrimination, i.e. an arrangement whereby plugs and receptacles of different rated voltages or currents are physically prevented from being engaged.

The requirements of AS/NZS 1747 should be considered in the design of these devices.

NOTES:

1 The term ‘receptacle' as used in this Standard is synonymous with the term ‘socket-outlet' in AS/NZS 3000. The term ‘receptacle' has been chosen to avoid confusion with the individual sockets within the plug.

2 Appendix A lists the information that a user should provide with any enquiry or order.

3 Appendix C lists the information which should be supplied by the designer or manufacturer.

4 A typical plug and receptacle (quick-release) assembly is shown in Figure 1.1 and a typical restrained back-to-back receptacle is shown in Figure 1.2.