Installing electrics to shed

Discussion in 'Electricians' Talk' started by garmcqui, Apr 13, 2019.

  1. garmcqui

    garmcqui Member

    Hi all, just put up a new shed yesterday, and want to get an electrical supply to it. Only for a light and double socket.

    There is an outdoor junction box on garage wall, where electrician took feed from fuse box to garage, and the SWA joins to t&e in there.

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    Would it be permissible to run a 4mm SWA cable from here to shed (approx 12m), clipped to garage wall?

  2. Coloumb

    Coloumb Well-Known Member

    That's dog rough the way the twin has been put through the back box. Why can't some people just take the tinniest bit of interest in doing a decent job?
    garmcqui likes this.
  3. Bazza

    Bazza Well-Known Member

    You could.

    1. Is the circuit RCD protected?
    2. Do you know how to terminate SWA cable & glands?
    3. How will you engineer the socket and light at the shed?
    garmcqui likes this.
  4. MGW

    MGW Well-Known Member

    As said as long as rules are followed yes permissible, however we simply don't know enough to know if the rules would be followed.

    So where do you live? In Wales that would be a special location, what sizes are those cables? what protection is there, etc.
    garmcqui likes this.
  5. garmcqui

    garmcqui Member

    Live in England, so not a special location I believe.

    The existing cables going into and out of the junction box are 10mm I believe? Had to be quite beefy as I have a 32A electric car charger in garage.

    Regarding terminating SWA, yes done it once before.

    Current protection - the house is all RCD protected from main consumer unit. Garage has its own 3 way consumer unit, with RCD. Annoyingly, this particular junction box isn’t protected, as the feed for the garage was taken from the meter cabinet 1m away, rather than from the main consumer unit at other side of the house.

    I was planning to fit a similar mini consumer unit in shed, to give RCD protection and have separate circuit for light and socket.
  6. Bazza

    Bazza Well-Known Member

    What size MCB is protecting this circuit ?
    What size is the cable actually? Believing it to be 10mm isn’t enough. The size should be embossed on the sheath of the SWA. It may say something like 3 x 6 or suchlike.
  7. nigel willson

    nigel willson Well-Known Member

    Be installing and testing an earth rod forTT then?
  8. spinlondon

    spinlondon Well-Known Member

    There’s no banjo or fly lead on that cable.
    Get whoever did that to come back and do it properly.
  9. nigel willson

    nigel willson Well-Known Member

    No earth sleeve on the black either
  10. Philip Hyde

    Philip Hyde Member

    Or Blue on Grey neutral??
  11. Bazza-spark

    Bazza-spark Well-Known Member

    From the photo, it is a positively dangerous install. The wire armouring isn't earthed in any way, shape or form. As said previously, get the idiot that did it back to sort it.

    I would like to see the gland used as well, I bet it isn't an external gland. Pull back the black sleeve and post a photo please.

    Kind regards
  12. Philip Hyde

    Philip Hyde Member

    Agree with quality of the job But It could be earthed garage end if its glanded off in a metal consumer unit or banjo earthed. Just not a parallel path
  13. Philip Hyde

    Philip Hyde Member

    Yeah almost certainly an indoor gland Not a long enough rubber boot :-(
  14. Bazza-spark

    Bazza-spark Well-Known Member

    Unless it is 3 core or TT I highly doubt it. Don't know any spark who would earth from the tail end rather than the feed end.

    Total carp install! I am fed up of repairing installs like this in our factory, let alone anywhere else.

    Kind regards
  15. Coloumb

    Coloumb Well-Known Member

    Just can't get the staff these days...
  16. Bazza-spark

    Bazza-spark Well-Known Member

    Hi Col


    This was the latest.

    Attached Files:

    Coloumb likes this.
  17. Bazza-spark

    Bazza-spark Well-Known Member

    What clock?
  18. garmcqui

    garmcqui Member

    Thanks for the info above all - now you’ve got me worried

    Regarding the SWA gland, will get a photo tomorrow.

    Regarding earthing, isn’t one of the 3 cores in the SWA being used as the earth (black wire)? There is also an earth rod driven into the driveway outside the garage, he said this was required for the EV charger anyway? Could this be providing earth for the whole garage, or just the EV charger?

    Photo of inside of meter cupboard attached. Looks like what they’ve done is cut the tails coming from the main switch and put in a 100A connector block to connect the garage supply into.


    The t&e going through the wall goes into a 3-way metal consumer unit In the garage, if that helps?
    Last edited: Apr 13, 2019
  19. Bazza-spark

    Bazza-spark Well-Known Member

    The wire armouring doesn't look as if it is earthed so under fault conditions can become live and lethal. It needs checking to make sure it is.

    Kind regards
  20. garmcqui

    garmcqui Member

    Makes sense, and it could be earthed at either end of the cable? Will check the other end tomorrow too.

    Annoyingly, I snapped two of the screws taking the lid of the ****** plastic enclosure, so will have fun fun with the screw extractor tomorrow!

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