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

(iii) small isolated metal parts such as bolts, rivets, nameplates and
cable clips which owing to their small dimensions or their
disposition cannot be gripped or contacted by a major surface
of the human body in excess of 50 mm × 50 mm;
(iv) fixing screws for non-metallic accessories provided that there is
no appreciable risk of the screws coming into contact with live
parts;
(v) short lengths of metal conduit for mechanical protection of
cables having a non-metallic sheath.
(3) Circuit protective conductor (CPC)
(a) For every socket outlet, a separate circuit protective conductor of
adequate size should be provided connecting the earthing terminal
of the socket outlet and the earthing terminal inside the enclosure
accommodating the socket outlet if the CPC is formed by the
enclosure.
(b) For every length of flexible conduit, a separate circuit protective
conductor of adequate size should be provided to ensure the earth
continuity of the installation between the two ends of the flexible
conduit.
(c) Adjacent sections of a busbar trunking used as a CPC should be
connected by a protective conductor of adequate size e.g. copper
tape or link to ensure the earth continuity between the two sections.
This requirement may be waived if it is certified by the manufacturer
of the busbar trunking that the earth continuity between the
adjacent sections of the busbar trunking is ensured by using the
connection accessories provided by the manufacturer.
(d ) The circuit protective conductor of every ring final circuit (other than
that formed by the metal covering or enclosure of a cable) should be
run in the form of a ring having both ends connected to the earthing
terminal at the origin of the circuit.
11E Equipotential Bonding
(a) In each installation, main equipotential bonding conductors should be
connected to the main earthing terminal for all extraneous conductive
parts to create an equipotential zone; such conductive parts include:
(i) main water pipes;
(ii) gas installation pipes;
(iii) other service pipes and ducting;
(iv) risers and ductings of central heating and air-conditioning systems;
and
(v) exposed metallic parts of structural framework.
71