AS 3439.4:2009 Low-voltage switchgear and controlgear assemblies
Each LV/LV unit consists essentially of
a) the protective and control devices on the primary circuit;
b) the LV/LV transformer, which shall be an isolating transformer in accordance with IEC 61 558;
c) the protective and control devices for the output circuit(s);
d) the outlets, either terminals or socket-outlets. Socket-outlets shall be protected as required in 1 01 .5 d).
Notwithstanding item b), the transformer need not to be an isolating transformer if the neutral point is connected by a cable to an earthing terminal outside the enclosure. This cable shall be identified by a label placed inside the enclosure as close as possible to the terminal. Also in this case requirements a), c) and d) apply.
101 .5 Outgoing units
Each unit consists of one or several outgoing circuits.
a) There shall be means for isolation, load switching, over-current protection and protection against indirect contact. These functions may be provided by one or more devices.
b) The load switching device shall be easily accessible without the use of a key or tool.
c) The switching device shall operate simultaneously on all poles and involve all the phase conductors. For switching the neutral conductor see IEC 60364-5-53 (Clause 536).
d) Socket-outlets shall be protected
– against direct contact or indirect contact according to IEC 60364-7-704 (Clause 704.471 );
NOTE 1 Where RCDs are used as means of protection, one RCD may protect several socket-outlets.However, consideration should be given to the effects of unintended tripping e.g. when the RCD protects more than 6 socket outlets.
NOTE 2 Where RCD are used, consideration should be given to the nature of the load e.g. the presence of high frequency and/or d.c. components.
– against overcurrent with protective devices with a rated current not exceeding the rated current of the socket-outlet. A protective device may protect more than one socket-outlet.
NOTE 3 Consideration should be given to effects of unintended tripping, e.g. when an overcurrent protective device protects more than 1 socket outlet.