There is a steel wire armoured cable (SWA) in my back garden that was put there by the previous owner. One end leads to the fuse board but is currently disconnected. The other end is loose at the edge of the lawn (with about 10m to spare), appearing from under the tarmac drive. The idea was to bury it under the grass, leading to the shed down the lawn a little bit - but that bit was never completed.

The cable was then damaged (see pic) just past the point where it appears from under the tarmac - the previous owner said the lawnmower had hit it. I'm also a little concerned that the plastic coating might be a little stiffer now than it was, although it is probably not too bad. There is a standard concrete kerb that the cable will do under right at the point of the damage to the cable.

I can't see any copper wire in the damage - it looks as if the inner insulation is intact, but I can see it.

I'm wondering what would now be the best way to repair the cable in order to lead it to the shed?

Many thanks, Ian

enter image description here

  • Are you sure that there's copper wire in there at all, and that the wires past the cracked green insulation aren't current-carrying aluminum conductors? What do the markings on the cable's jacket say exactly?
    – Nate S.
    Jul 2, 2019 at 19:30
  • Hi Nate, I'm not sure at all - I was just assuming. I've never done anything with these kinds of cables before. I think I read the markings as: ALCATEL IS275 ELECTRIC CABLE 600/1000V Cu/XLPE 3x6mm2.
    – Ian
    Jul 2, 2019 at 20:24
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    However, I still think the inner wires visible are the actual conductors, not a second layer of armor -- note that copper, when corroded, appears a dull grey-green, not shiny orange as it does when new. So as @Owain recommends below, the best option is to cut out this damaged part of the cable, and splice it in a suitable way for the location.
    – Nate S.
    Jul 2, 2019 at 21:38
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    The wire inside the light green sheath is copper ,darkened by corrosion. Jul 2, 2019 at 21:40
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    It would be worth a few seconds to scrape the outer wire with a knife to check if it is copper . Atmospheric corrosion of steel normally is brownish ; copper corrosion can be black like photo or more commonly some greenish color. That is , a chance the outer wire is copper also. Jul 2, 2019 at 21:48

3 Answers 3


It would be best to cut out the damaged section and replace it with a suitable gel-filled junction box (or two junction boxes and a new bit, if there isn't any slack).

https://www.tlc-direct.co.uk/Products/WKSH506W.html or https://www.tlc-direct.co.uk/Products/SWJK1.html

may be suitable.

Your cable size is 3 x 6mm2 copper.

  • Just FYI all this time later, this is what I did in the end. I cut it and joined with a junction box like this. I think they called it a submarine as it was clear plastic in the shape of a submarine. Used a dremel to cut it precisely, wired it up, and put the resin in. Worked perfectly. Thanks for the help.
    – Ian
    Jun 14, 2020 at 18:27

What I have seen done on oilfield leases, is to cut away the loose insulation (the black bit), wrap it in waterproof (resistant) electrical tape - then wrap on top of that in an off coloured electrical tape to show that it has been repaired. I don't know how up to code that would be, but if it works for them...maybe it will work for you.


If the cable was able to be damaged by a lawnmower I don't think it was applied and installed properly, so I doubt that any suggestions made on repairing it will render it code compliant after the fact.

That said, it appears as though the integrity of the inner jacket is compromised and although it is LIKELY that the inner conductors have some sort of water resistant insulation, it's something I would not assume. Were I to make a repair on it, tape would be inadequate in my opinion. Since you apparently have access to the end of the cable I would use heat shrink heavy wall tubing, and use the kind with heat activated sealant installed. enter image description here

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