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

(Earth leakage and earth fault currents) even if the bonding is
disconnected.
(4) Application of Code 12B
Code 12B applies only to an installation that is completed or substantially
altered on or after the commencement of the Wiring Regulations (1 June
1992).
12C Earth Electrode
(1) Types of earth electrodes
(a) The material used and the construction of the earth electrodes
should be such as to withstand damage due to corrosion. The
following types of earth electrodes are acceptable:
(i) earth rods or pipes;
(ii) earth tapes or wires;
(iii) earth plates;
(iv) metallic reinforcement of concrete, including sheet piles.
(b) the metalwork of gas and water services should not be used as an
earth electrode.
(2) Rod electrode
(a) The overall diameter of copper rod electrode should not be less than
12.5 mm.
(b) The overall diameter of a rod electrode of materials such as stainless
steel and galvanised steel should not be less than 16 mm.
(c) A hardened steel point may be fitted to the penetrating end of the
rod electrode.
(d ) Additional lengths of rod, whenever required, should each be
connected together by a coupling.
(e) For installation of additional rods, it is recommended that a mutual
separation of 3.5 m or a distance greater than twice the driven
length should be maintained. All rods thus installed should be
connected together by means of earthing conductors of adequate
size enclosed in PVC ducts and laid at a minimum depth of 600 mm
below the ground surface.
(3) Tape electrode
(a) Tape electrodes should be copper strip having a cross-section of not
less than 25 mm × 3 mm.
(b) In case where several tapes are required for connection in parallel to
achieve a low earthing resistance, they may be installed in parallel
lines or they may radiate from a point.
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