The IEE Wiring Regulations Explained and Illustrated, 2nd Edition

Circuit design

Thermal constraints

[IEE Regs 543]

The IEE Regulations require that we either select or check the size

of a CPC against Table 54F, or calculate its size using an adiabatic

equation.

Selection of CPC using Table 54G

Table 54G simply tells us that

1 For phase conductors up to and including

16

mm

2

, the CPC

should be at least the same size.

2 For sizes between

16

m

2

and

35

mm

2

, the CPC should be at least

16

mm.

3 For sizes of phase conductor over

35

mm

2

, the CPC should be at

least half this size.

This

is

all very

well,

but for large sizes of phase conductor the CPC

is also large and hence costly to supply and install. Also, com-