Trench Depth for underground cable...

[SSE]

Running a supply from the house to the garage, just about to dig the trench for the ducting but wondered what depth it has to be? The cable will cross underneath a slabbed path before going about 2 metres max across (under!) the garden.

 

[Goody]

As a rule of thumb it's 600 mm deep and again it's entirely up to your own judgement, I guess!

 

[Deleted member 26818]

There's no depth specified in BS7671 other than for Horticultural/Agricultural installations.
Just for the cable to be at a depth sufficient to prevent it being damaged.
Most people would probably recommend 500-600mm, laid on a bed of soft sand to prevent damage from sharp stones, with a layer of tape or tiles about 200mm from the surface.

 

[BillyTheSparks]

At a suitable depth for the foreseeable future.

This is what I was taught at college, I would probably bury at a depth of 4"-8" as its buried beneath the slabs. And would still put soft sand around it and caution tape just below the slab.

(I know this will upset someone on here)

 

[Spudnik]

50mm duct!

 

[Engineer54]

At a suitable depth for the foreseeable future.

This is what I was taught at college, I would probably bury at a depth of 4"-8" as its buried beneath the slabs. And would still put soft sand around it and caution tape just below the slab.

(I know this will upset someone on here)

Your right!!!! 4 to 8 inches??? ...My God!!! And what do you suggest for the 2m or so not covered by paving slabs ...8 to 10''?? No-ones said how these slabs are going to be laid, they may just be sitting on a dry sand/cement base, and not a substantial concrete/mortar base....

For short cable runs such as this you could do well to provide a 50mm duct as Jason suggests ....but even that needs a depth a dam sight more than 4 inches!!! ....The mind boggles at times, reading such things as this!!!!

 

[BillyTheSparks]

Sorry didnt read that it was going under the garden!!

In that case then I would bury it at s suitable depth, 18" with caution tape just below the surface.

DIDN'T MEAN TO UPSET YOU E54!!!!

 

[Octopus]

I have to say this is an area of the regs where the ambiguity is not helpful.

600mm under gardens,
400mm under paths etc

tin hat on!