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

Code 13 CONDUCTORS, JOINTS AND
CONNECTIONS
13A Selection and Sizing of Cable Conductors
(1) General
A conductor should have a current carrying capacity not less than the
maximum current demand it normally carries, be capable of withstanding
the prospective fault current, and suitable for operation in the
environment and at the design voltage of the installation.
(2) Factors to be considered in sizing of cable conductors
In general, sizing of cable conductors should take into account the
following factors:
(a) the conductor material;
(b) the insulating material;
(c) the ambient temperature in which the cable is installed;
(d ) the method of installation;
(e) whether or not the cable is affected by thermal insulating material;
( f ) the use and type of protective device;
(g) the voltage drop from the origin of the circuit to the load; and
(h) for Category 1 circuits, live conductors should have a cross-sectional
area:
(i) not less than 1.5 mm2 for surface wiring using PVC insulated
PVC sheath copper cables;
(ii) not less than 1.0 mm2 for single core PVC insulated copper
cables installed in conduit, duct, ducting or trunking;
(iii) not less than 16 mm2 for aluminium conductors;
(iv) not less than 0.5 mm2 for flexible cables and flexible cords.
(3) Method of sizing cable conductors
(a) In determining the size of cable conductors to be used, the steps
employed, in general, are as follows:
(i) Determine the design current of the circuit under consideration.
(ii) Choose a suitable overcurrent protective device (refer to
Code 9).
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