Alternative to SWA

[PeterC]

My brother 'phoned for some advice on wiring his 'shed' (more like a barn in size). He wants to run a ne supply cable to replace the 2.5 FT&E.

The run is about 40m, some clipped to a wall and some buried under a path. The loading is about 15A peak.

He's hoping to get away with 4mm - I feel that 6mm might be less of a throttle on machines. I don't know his mains voltage (rural Wales, so...) and I can't really get an idea of his CU as he knows little about electricity. He does have a 'tame' electrician who'll do the job, but the chap hates SWA and has hardly ever used it.

I've seen in this group some mention of other protected cable - mesh, IIRC - but can't unforget what it was (annoying, because I used the stuff at work about 25 years ago).

Any pointers much appreciated.

[js.b1]

SY CY etc are not suitable for this application. Reasons are cost (I think it costs more than SWA in the same size), glands are costly, braid has low coverage & no armour capability, sheath is weaker re direct burial, some manufacturers specs restrict "direct connection to public electrical supply" which can make DNO staff baulk. They are aimed at HVAC system control & power. I believe the HSE keeps mentioning them for extension leads, but as many sparks condemn as condone such use.

First is identify what earthing system is in use - and to be used at the other end re incoming services & structural metalwork, building dampness re concrete in a pond or wooden shed on sleepers.

Second if being tight fisted then you could use 4mm SWA. I say that for two reasons - first, if voltage drop is outside spec on 17th for lights then note it as a departure on the certificate and second, better to do that than leave FTE 2.5 in the ground which is not really acceptable.

Third fit an Em-Light if the RCD is at the house end (ie, SWA does not run all the way to the CU) if power tools such as a circular saw in use.

If the spark can not do a CW gland in their sleep... um... get the exact length of cable including the trench measured, order the cable & glands yourself, make them off with a Bahco 9031 wide-jaw =A316 from Amazon, repackage and send on to him.

[Andrew Mawson]

really get

mesh, IIRC -

SWA is the way to go, and the chap needs to get over his fear of it. A concern I used to share, but I've had to put loads in here at the farm. Those SWA strippers that work a bit like a pipe cutter make the job relatively simple, and the modern Piranha nuts overcome the problems of plastic consumer units. Personally for single phase I always use three core, and parallel one core with the armour for earth/cpc connections. Mostly 2.5 / 4 / 6 &10mm so far, but I'll admit to putting off a run of 35mm three phase that needs doing before the spring!

AWEM

[ARWadsworth]

Then do not use him. As he is obviously not an electrician.

SWA terminations are not difficult.

And js.b1? Have you got a name? js.b1 makes you sound like a droid in StarWars.

[Dave Plowman (News)]

Then find a 'wild' one. SWA is the obvious choice for many jobs and not difficult to use. The alternatives might be steel conduit or Pyro - both far more difficult to use.

[John Rumm]

Offer him a printout of:

our compliments! ;-)

SWA is the ideal choice for this app, why fight it?

[js.b1]

The larger sizes of SWA can be difficult to handle.

Worst is where you have SWA threaded through a short run of flexible conduit just to go under foundations, sleepers, path. You may be holding the flexible conduit, but the slippery inner surface of the conduit allows SWA to thrash very suddenly and send spectacles flying.

Some people wrap their legs around the cable to control it and just roll around on the floor to rotate the cable so as to complete a 360 degree cut. A rotary pipe cutter removes the need to reposition the cable in order to cut 360 degrees, but if cutting near the end the cutter's steel rollers can massage the sheath along the cable so the armour gets a wandering rather than repeating cut. I have not tried it, but suspect a jubilee clip on the end of the cable might stop the sheath "walking" - or I might have blunted and chipped the cutting wheel :-)

[js.b1]

Julian :-)

I do not use my surname because my web business uses it, that's why, no magic reason.

[ARWadsworth]

Ta

[PeterC]

Coincidence - same as my brother, the one who wants to wire his shed.

[PeterC]

OK, replying to myself, top-posting etc.:

Thank you all for the advice. I'll point him at the Wiki and paste replies into an e-mail. He'll just have to sort it out with his electrician.

Thanks, Peter.

[Tim Lamb]

In message , js.b1 writes

Nobody heard of junior hacksaws?

You don't have to cut right through: just enough to allow a couple of bends to fracture the wires.

regards

[John Rumm]

The blade runner is worth getting IMO - its much easier than a pipe cutter and quite a bit quicker.

[Owain]

Especially in rural Wales, where electricians should be used to outbuildings and the like.

Owain

[PeterC]

He's actually done a lot of it - caravan and chalet sites, schools etc. - he just hates it!

[Tabby]

Pyro's less reliable too, damp liable to get into it eventually, and pyro and damp are a non-working combination.

NT

[Dave Plowman (News)]

Damp only gets in if it's badly terminated or damaged in other ways. But I only mentioned it in passing - SWA is the obvious route to go down.

[dennis]

Seconded, SWA is easy once you know how to cut the armour (I have side cutters that can cut the armour of small stuff with ease).

[ARWadsworth]

So two more joints will not hurt him then.

Your brother will still need 6mm to meet 17th edition voltage drop rules on the lights.

[Andrew Mawson]

Pyro - both

I find my battery operated DeWalt angle grinder with a 1mm disc indispensible handling both SWA and heavy meter tails. You can make a very neat cut end that dosn't splay one jot, whereas using crops tends to make the conductor bundle spread and hard in the larger sizes to get into screw terminastions.

AWEM