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

(d ) Where a residual current device is used, it should:
(i) pass type test to IEC 61008 (for RCCB) or IEC 61009 (for RCBO)
or equivalent;
(ii) be suitable for independent toggle operation;
(iii) have its tripping operation not dependent on a separate
auxiliary supply; and
(iv) have an integral test device on the front of every RCD to enable
the automatic tripping operation to be tested by simulation of
an earth fault condition.
(e) When two or more residual current devices are installed in series and
where discrimination of their operation is necessary to prevent
danger, the characteristics of the devices should be arranged to
achieve the intended discrimination. In general, a time delay should
be provided in the upstream device, for example, by the use of a
“Type S” (or selective) device.
11K Earth Electrodes
Requirements for earth electrodes are described in Code 12.
Table 11(1)
Minimum Cross-sectional Area of Separate Protective Conductor
Installation
Method
PVC Insulated (mm 2 ) Bare (mm 2 )
Copper Aluminium Copper Aluminium
Surface wiring 2.5 (sheathed) 16
4.0 (non-sheathed)
In Conduits or
trunkings
> 6 16
1.0 16 1.0 16
76