SWA supply to outbuilding

[Handy Andy]

Be grateful for some advice from the electricians here.

I've been asked by a relative to complete an electrical installation to a garden shed/outbuilding. The electrician originally asked to do this job has disappeared after partially completing it. He has connected a roll of SWA via an isolator, but that is as far as he got.

It's a relatively simple matter of running the SWA to a CU in the outbuilding and putting in some lights and a couple of sockets. The problem is that the appliances to be installed in there will use about

6kW of power and I'm not sure that the SWA is rated high enough. The run is a good 25 metres and I can't tell exactly what size the cable is.

It looks about 4mm but all I can on it is the following: BASEC ELECTRICAL 600/1000 BS 5467 2017.

Doesn't tell me much, does anyone here know how its size/rating can be determined?

[Andrew Mawson]

Accurately measure the outer diameter and compare with the likely sizes on the TLC web site

If you follow the link for each cable type the o/d is quoted

Andrew

[harry]

Snip a little bit off one of the cores and compare the size of the conductors with a known bit of cable in one of the sheds/DIY shops (B&Q etc)

[Handy Andy]

Andrew/Harry

Many thanks for the excellent ideas.

[John Rumm]

Alternatively, they are all in one table here:

[John Rumm]

Full details of what you need to do are covered here:

However, if you have 6kW of load, that's about 26A total. At 12mV/A/m voltage drop (if it is 4mm^2) that puts you at about 6.9V at 25m, which is just about ok. Current carrying capacity is ample for that load.

[Tim Lamb]

ISTR various earlier threads about exporting earths, suitability of cable armouring for that purpose and local earth rods.

[John Rumm]

Yup that's in that article above as well.

[Handy Andy]

Very useful information. Thanks for that.

The SWA route to the outbuilding is across some pretty difficult ground, so burying the cable in places is liable to be quite a problem, any views on an alternative?

[FMurtz]

ANFO ? :)

[John Rumm]

It does not have to be buried. It can fixed to any suitable structure (i.e. preferable not something "temporary" like fence panels). All you are really attempting to do it keep it out of harms way.

[Tim Lamb]

You could find someone local with compressed air moleing tackle.

Alternatively, if it is only concrete paths or other small obstacles, you could trench either side and then whack a length of steel water pipe through with a sledge hammer. Doesn't work too well in Herts. with our flints!

[charles]

you aren't the only ones to have flints