[Question] Standard for depth of external electrical conduits

[KThomas]

I can't seem to access the SABS Building standards, and I need to know the standard on the depth one should bury a uPVC conduit across a garden. The conduit carries electrical wires for the outside lights. Can anyone help advise?

[ians]

it is good practice to bury it at least 300 mm below FFL ... unless it has mechanical protection ... I normally throw a thin layer of concrete and lay danger tape 100 mm above the pipe ... I am sure one of the technical guys will attached sabs regs.

[GCE]

Hi

I would stick to below 0,5m for a conduit and if going close to or under a flower bed even deeper with a layer of bricks end to end over the conduit for protection.
The regulations allow less but rather be safe than sorry.

There are 2 reg's you need to think on - Have pasted below

6.4 Positioning and fixing of cables
6.4.1 Positioning
A cable shall not be run
a) in the same trench or wireway as a supplier's cable, except with the
supplier's permission,
b) in the same wireway as the cables or wires of telecommunication, radio
and signalling circuits that are not covered by this part of SANS 10142,
c) where it is likely to be damaged by liquids such as oil, acid, acetone and
alkali or by gases such as sulfur dioxide,
d) within 150 mm of hot services such as hot pipes and flues if the heat is
likely to damage the cable, unless the cable is cooled or shielded from
heat, or
e) in a position where it is likely to be damaged, unless it is mechanically
protected.



6.4.4.2 If unarmoured insulated cables are buried at a depth of
a) less than 0,5 m, they shall be enclosed in conduit or otherwise
mechanically protected (for example, in the case of paving or concrete)
(see also 6.5.), or protected by an earth leakage protection device with a
rated earth leakage tripping current (rated residual current) IΔn not
exceeding 30 mA, or
b) at least 0,5 m, the backfill around them shall not contain sharp objects
and there shall be a marker tape that runs above the route of the cable, at
a depth of between 0,3 m and 0,4 m.

[ians]

This would be a good example of an application for a single RCBO ... generally people wouldnt put lights on earth leakage due to nuicense tripping ... a dedicated unit for the outside/garden lights.

If you had to consider kids on the property ... you never know if the kids or grand kids are going to play in the garden ... that cable has to come out the ground somewhere ... I have seen many a property where the lights in the garden are damaged and wires exposed ... as I am typing this should be a law ... considering the SANS is dedicated to huaman and animals safety.