Code of Practice for the Electricity (Wiring) Regulations - 2009 Edition

(e) Conductive component parts of socket outlets should be so located and
separated that, in normal use, they cannot be displaced so as to affect
adversely the safety or proper operation of the socket outlet.
(f ) Where the socket outlet is required to be weatherproof, it should be
totally enclosed when fitted with screwed conduits, or PVC sheathed
cables and without a plug in position. The socket outlets should be
threaded with dimensions given in Figure A3(3) for use with the
corresponding screwed ring fitted to plugs.
(g) For a ring or radial final circuit feeding a number of socket outlets and
where:
(i) the circuit has one pole earthed, the socket outlet should be of the
type that will accept only 2-pole-and-earth contact plugs with singlepole
fusing on the live pole. Such socket outlets with raised socket
keys are shown in Figure A3(4), and those with socket keyways
recessed at position ‘B’ are shown in Figure A3(5).
(ii) the circuit has neither pole earthed (e.g. a circuit supplied from a
double-wound transformer having the midpoint of its secondary
winding earthed), the socket outlet should be of the type that will
accept only 2-pole-and-earth contact plugs with double-pole fusing.
Such socket outlet is those which have raised socket keys as shown
in Figure A3(4), together with socket keyways recessed at position
‘P’ as shown in figure A3(5).
(4) Construction of terminals
(a) Connection should be made by means of screws, nuts or equally effective
devices.
(b) When pillar type terminals are used, they should comply with the
following requirements:
(i) the minimum dimensions are in accordance with Figure A3(2).
(ii) the cable clamping screws should be long enough to reach the
opposite surface of the cable hole, and should have rounded ends,
and
(iii) the surface of the cable hole against which the cable is clamped
should be smooth and unbroken.
(c) Terminals should be effectively enclosed. Insulating barriers securely fixed
to, or forming an integral part of the interiors, should be provided to
separate internal metal at different potential including any bare flexible
conductors, even if such conductors should become detached from their
terminals.
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