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

Code 14 WIRING INSTALLATION ENCLOSURE
14A General Requirements
(1) Enclosures as protective conductors
(a) Metallic enclosures for cables, busbar trunking and switchgear and
controlgear assemblies, where used as protective conductors should:
(i) have a cross-sectional area not less than that determined from
the application of Code 11C(2)(e) or verified by test in
accordance with IEC 60439-1 or equivalent;
(ii) have an electrical continuity achieved and maintained to afford
protection against mechanical, chemical or electrochemical
deterioration; and
(iii) permit the connection of other protective conductors at every
predetermined tap-off point.
(b) Where conduit, trunking or ducting are used as a protective
conductor, the earthing terminal of each accessory should be
connected by a separate protective conductor of adequate size to an
earthing terminal incorporated in the associated box or enclosure.
(2) Support of enclosures
All conduit, ducting and trunking installations should be properly
supported and of a type suitable for any risk of mechanical damage to
which they may be liable in normal conditions of service or adequately
protected against such damage.
(3) Fire barrier
(a) Where conduit, duct, ducting or trunking pass through fire-resistant
structural elements such as floors and walls designated as fire
barriers, the opening made should be sealed according to the fire
resistance requirements of BS 476:Part 20 or equivalent.
(b) Where cables, conduits or conductors are installed in channel, duct,
ducting, trunking or shaft which pass through fire-resistant structural
elements, suitable internal fire-resistant barriers should be provided
to prevent the spread of fire.
14B Steel Conduit System
(1) Construction
(a) Steel conduits and fitting with metric thread, except flexible conduits,
should be of heavy gauge, longitudinally welded type and comply with
BS4568, BS EN 60423, BS EN 61386, IEC 60423, IEC 61386 or
equivalent. The nominal minimum outside diameter of any rigid conduit
to be used should be 16 mm with a minimum wall thickness of 1.4 mm.
96