The IEE Wiring Regulations Explained and Illustrated, 2nd Edition

Earthing

present,

10.0

mm

2

. For example, most new domestic install-

ations now have a

16.00

mm

2

earthing conductor, so all main

bonding will be in 10.0mm

2

. Supplementary bonding conduc-

tors are subject to a minimum of 2.5 mm

2

if mechanically

protected or 4.0 mm

2

if not. However, if these bonding conduc-

tors are connected to exposed conductive parts, they must be

the same size as the CPC connected to the exposed conductive

part, once again subject to the minimum sizes mentioned. It is

sometimes difficult to protect a bonding conductor mechani-

cally throughout its length, and especially at terminations, so it

is perhaps better to use 4.0 mm

2

a ...