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

(i) Adjacent or parallel conduits cast in concrete should be separated by
a spacing of not less than 25 mm.
(2) Wiring installation using steel conduit
(a) (i) Joint in steel conduits should be made by means of a solid
coupler into which the adjacent ends of the two conduits
should be inserted and screwed up tightly in order to make the
conduit run mechanically and electrically continuous. Exposed
screw threads should be painted with anti-corrosion paint.
(ii) Running couplings are not recommended.
(b) (i) Where a steel conduit terminates at a metal casing, the
connection should be made by a coupler or a brass adaptor for
flexible conduit together with a brass male bush. The connection
between the flexible conduit and the adaptor should be securely
fixed and protected against ingress of moisture where required.
Length of each flexible conduit should be kept to a minimum of
not more than 1 m for general applications or 2 m inside false
ceiling.
(ii) Where the metal casing is painted or enamelled, the electrical
continuity between the conduit and the casing should be
achieved by means of a separate protective conductor of
adequate size, connecting the earthing terminal of the conduit
and an earthing terminal inside the metal casing. A copper
earthing piece placed between the bush and the metal casing
may be used as an earthing terminal of the conduit.
(c) Conduit should not be bent more than 90 degrees. The internal
radius of the bend should not be less than 2.5 times the outside
diameter of the conduit.
(3) Wiring installation using PVC or plastic conduit
(a) Conduit bends should have an internal radius of at least 4 times the
outside diameter of the conduit.
(b) The method of carrying out the conduit bends, conduit joints, fixing
conduits to boxes without spouts, and the tools and materials to be
used should be as recommended by the manufacturer of the
conduits.
(c) Due allowance should be made for the expansion of the PVC tubing
at high temperatures. Expansion coupling or other fittings should be
included in a straight run of 8 m or more. Saddles or clips should be
of sliding fit.
(d ) Boxes for the suspension of luminaires or other equipment, where
considerable heat will be produced, should be fitted with steel insert
clips. Plastic boxes used for suspension of luminaires or other
155