Width of trench for burying SWA

jon92 · 7 Jan 2014

I am in the process of running 3 core 6mm SWA to my shed. I had to pass it under a patio and to save lifting the slabs I removed the mortar in between some of them (about 50mm wide) and dug down between the slabs. I put a layer of sharp sand in around the cable and pushed warning tape on top. Now I am wondering if the cable is ok in such a narrow trench - the sand will not really protect it at the sides so I'm wondering if there is a danger of damage from sharp stones in the soil. Also the tape obviously cannot spread out to its full width.
I thought I was using my initiative but it wouldn't be the first time that had got me into trouble. Your opinions appreciated.

sparkwright · 7 Jan 2014

Have you filled it in yet?

Gutterball · 7 Jan 2014

how deep is it?

PrenticeBoyofDerry · 7 Jan 2014

You area aware that new circuits require notification to building controls, then inspecting, testing prior to commissioning.
If this is DIY you should have already notified prior to starting work, unless you are able to self cert and therefore you should know the answer to your question.

jon92 · 7 Jan 2014

The trench is about 45-50cm deep measured from the top of the paving. I've put some of the soil back in but not mortared between the slabs yet.
Thanks for the info about Building Control, a Building Notice has been submitted already.

flyingsparks · 7 Jan 2014

450mm is the required depth so sounds ok.

PrenticeBoyofDerry · 8 Jan 2014

450mm is good, it could be worth routing within a duct and running in a extra pull rope, just in case it ever needs replacing.

ban-all-sheds · 8 Jan 2014

Would love to know how you managed to dig a 450-500mm deep trench only 50mm wide.

Sherbertlion · 8 Jan 2014

ban-all-sheds said:
Would love to know how you managed to dig a 450-500mm deep trench only 50mm wide.

http://alchemybar.com/product/bar-spoon-with-fork-50cm/

jon92 · 8 Jan 2014

Wish I'd known about the spoon/fork combo, instead I used a 600mm auger bit. It was rather a laborious job, possibly one of those where the short cut took longer than the long way (i.e. lifting and replacing the slabs) - classic DIY error!

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Width of trench for burying SWA

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