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

(b) Flexible steel conduits should comply with BS EN 61386, IEC 61386
or equivalent. In addition, where flexible conduits are exposed to
weather or in damp situations, the conduits should be of the metallic
type with PVC oversheath.
(c) All steel conduits, conduit fittings and the associated metallic boxes
for the enclosure of electrical accessories should be protected
against corrosion on both the inside and outside surfaces.
(2) Installation
(a) The steel conduit installation should be made mechanically and
electrically continuous throughout, be effectively earthed and
comply with BS4568, BS EN 60423, BS EN 61386, IEC 60423, IEC
61386 or equivalent.
(b) An adequate number of suitably sized adaptable boxes should be
provided in the conduit installation to enable cables to be drawn in
easily and without damage.
(c) Flexible steel conduit should not be used as a protective conductor
and it should have a separate circuit protective conductor of
adequate size for earth continuity.
(d ) Conduits should be installed so as to prevent accumulation of
condensed moisture or water in any part of the installations.
14C Steel Trunking System
(1) Construction
(a) Steel trunking and fittings should be fabricated with sheet steel
having a minimum thickness as indicated in Table 14(1) and should
comply with the requirements specified in BS4678: Part 1 or
equivalent.
(b) Underfloor trunking should be compatible to the requirements laid
down in BS4678: Part 2 or equivalent and should be fabricated with
sheet steel of:
(i) not less than 1.2 mm thickness for compartment width up to
and including 100 mm;
(ii) not less than 1.6 mm thickness for compartment width over
100 mm; and
(iii) not less than 1.0 mm thickness for the partitions and connector
material.
(c) Steel trunking installations should be constructed using manufacturer’s
standard fittings such as tee or angle pieces, connectors
etc., throughout as far as practicable.
(d ) All steel trunking and fittings should be protected against corrosion.
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