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

(2) Installation of PVC insulated, PVC sheathed non-armoured cable
(a) Where protection is required for cables running up a wall from the
floor, a metal channel cover should be fixed to a minimum height of
1.5 metres above finished floor level.
(b) Where cables pass through a building structure such as wall, column
or floor slab, the cables should be drawn through PVC or G.I. sleeves
inserted into the building structure as illustrated in Figure 25(3) and
sealed up with proper fire resisting material of the same Fire
Resisting Period according to the requirements of BS 476:Part 20 or
equivalent.
(c) When cables are routed along or across steel joints, beams,
stanchions, etc. they should be enclosed in steel or rigid PVC
trunking/conduit.
(d ) Rubber grommets or insulated bushes should be used to protect the
non-armoured cables passing through metal box or any other metal
work.
(e) Buckle clips should be:
(i) provided along the entire cable route at regular intervals not
exceeding the spacing in Table 25(3);
(ii) provided at a distance not exceeding 75 mm from a termination
and from both sides of a bend;
(iii) fixed and secured by pins with wall plug inserted to a minimum
depth of 20 mm to the surface of wall, column, partition or
ceiling. The head of every pin should be level with the surface
of the clip so that no damage to the sheath of the fixed cables
can occur; and every hole in the buckle clip should have a fixing
pin.
(f ) The neutral conductor of a twin core cable for a lighting final circuit
should be looped through an insulated connector enclosed in the
moulded box or pattress accommodating the switch.
(3) Installation of armoured or metallic sheathed cable
(a) Cables buried direct in ground should be armoured or metal
sheathed. Cables of Category 1 & 3 should be buried at a depth not
less than 450 mm and cables of Category 4 should be buried at a
depth not less than 750 mm. They should be protected by means of
cable cover tiles. The bottom of the cable trench should be first
covered by a layer of sand or fine soil to a depth not less than the
diameter of the cable before the cables are laid. Another layer of
sand or fine soil, to a depth of 100 mm over the cables, should then
be provided before the cable tiles are laid to protect the cables
throughout entire route.
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