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

(d ) The spacing of the socket contacts should correspond with that of the
plug pins as shown in Figure A1(1).
(e) On insertion of pins into contacts, the travel from the first point of
contact to the complete engagement, should not be less than the
minimum, or more than the maximum, given in Table A1(1).
Table A1(1) Contact Travel
Current Rating Minimum Maximum
(ampere) (mm) (mm)
5 4.17 6.25
15 4.75 6.83
(f ) Socket contacts should be self-adjusting as to contact making and each
socket contact should be such as to make and maintain, in normal use,
effective electrical and mechanical contact with the corresponding plug
pins. The means for producing the contact pressure should be associated
with each socket contact independently such that individual line or
neutral socket contact should be capable of retaining the withdrawal—
pull of a gauge as detailed in Figure A1(3) for 30 sec. when the socket
outlet is held horizontally with the gauge hanging vertically downwards.
It should be checked that neither shutter nor the cover/moulding has any
effect on the results.
(g) Where a shutter is provided, the construction of the socket outlet should
be such that when a plug is withdrawn from it, the current carrying
socket contacts are automatically screened by the shutter. The shutter
should be operated by the insertion of the earthing pin.
(h) (i) Unless a shutter is provided, diameter of holes in the socket outlet
plate or cover for the reception of the line and the neutral plug pins
should not exceed 5.8 mm or 7.7 mm for 5A or 15A socket outlet
respectively.
(ii) The holes for the line and the neutral plug pins in metal plates
should have insulated material of at least 2 mm thick around them.
(i) The socket outlet should be constructed to prevent a current carrying pin
of a plug from making contact with a current carrying contact of the
socket while either or both of other pins are completely exposed. The
provision of a shutter, or no part of hole intended for the reception of
line or neutral pin should be less than 16.5 mm or 21 mm from the edge
of a 5A or 15A socket outlet respectively, is acceptable for this purpose.
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