Cable sizing

[RBS]

Need a cable to run approx 100m from incoming supply to a new build house,cable will be buried under ground what is the mimimum size cable that could be used to make it comply with the regs? Copper/aluminium? Thanks

 

[DPG]

get ready for it..... daz

 

[Engineer54]

I worked on a new build 4 bed detached a couple of years ago. It was set back about 20 metres from the road and one trench was dug from the street to the house.

Into that trench went the gas supply - yellow Alkathene pipe run inside yellow plastic duct, water supply - blue Alkathene pipe and the electricity supply - split concentric cable.

All three services in the same 700mm deep trench resting on and surrounded by pea gravel before being back filled.

Pea gravel is not suitable to surround and compact around any type of direct buried cable, especially not with non-armoured concentric cable, ...Full Stop!! Cable in a suitable duct with a compacted surround of pea gravel you can get away with!!!... Cables should preferably always be laid on a soft sand bed and surrounded by compacted soft sand. At the very least, a bed of sifted soil and sifted compacted soil backfill....

 

[Geordie Spark]

Pea gravel is not suitable to surround and compact around any type of direct buried cable, especially not with non-armoured concentric cable, ...Full Stop!! Cable in a suitable duct with a compacted surround of pea gravel you can get away with!!!... Cables should preferably always be laid on a soft sand bed and surrounded by compacted soft sand. At the very least, a bed of sifted soil and sifted compacted soil backfill....

Be that as it may, that's what the contractors working for the DNO used !!

The trench was dug by the bloke who was building the house - it was a self-build - for himself, the contractor working for the gas supplier laid the gas pipe in it, the contractor working for the water supplier laid the water pipe in it, then the contractor working for the DNO laid the cable in it & covered the whole lot with pea gravel which they brought on a lorry. There was no sand - soft or otherwise - anywhere in sight.

After that, the bloke who dug the trench back filled it.

I have to say I was a bit dubious about the whole thing, but who am I to argue with the experts ??

In the end, my contribution to the project - which was the wiring, plumbing & heating installation - was all up to scratch, and that's all I was worried about.