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Twin core swa cable

Former Community Member
Former Community Member
I am putting a summerhouse in the garden.  There is an existing cable running from the house to the location of the new summerhouse.

It's not connected yet. 

The cable is twin core 25mm SWA.

Am I OK to use this for connection to the house electrics? 

Is the armour layer used for the earth? 

Thanks for any advice 

Dave

  • Hi DaveEyes.

    As that cable is rated at about 100 Amps, and presumably not 1/2 mile long it sounds fine. If the cable is terminated outside you need a type CW gland at the exposed end, which is quite tricky to fit if you have not done it before. If it is not subject to weather a type BW is OK and easier to fit. The gland must be the correct size for a 22mm cable (check when you buy them, it is often on the packet). The Armour acts as the Earth conductor and will be of sufficient size, but I suggest that the supply should be RCD protected at 30 mA. I suspect there is no exposed metalwork entering the summer house, in which case the Earthing system is not a particular concern. It is easiest to fit the gland into a metal box, which will provide good Earth continuity, and then a bolt to connect the Earth wires at both ends.

    I hope that helps


    David
  • if it really is 30 years old, do a few meter tests to verify the insulation is OK and the outer armour is still isolated from terra firma before buying glands etc. Who knows what may have happened below ground.

    M.
  • AJJewsbury:
    Don't forget the banjo!

    That's old school Tom! - these days I prefer an earthing nut - much tidier and easier and far better with plastic enclosures.

       - Andy.


    Here's one I prepared earlier .....
    16002cf478f4d7ff1082bfee6372f6bf-original-ab01.jpg

    Legh


  • Former Community Member
    0 Former Community Member
    Many thanks for your message.  Much appreciated.


    Dave
  • Legh Richardson:
    AJJewsbury:
    Don't forget the banjo!

    That's old school Tom! - these days I prefer an earthing nut - much tidier and easier and far better with plastic enclosures.

       - Andy.


    Here's one I prepared earlier .....
    16002cf478f4d7ff1082bfee6372f6bf-original-ab01.jpg

    Legh




    I find with this arrangement if using an earthing nut, that the earthing nut securing grub screw only just bites on the short threaded part of the S.W.A. gland, as the gland  is a bit short for this application. The Wiska box sides are quite thick.


    Also, I like to fit the S.W.A. gland body and eathing nut to the enclosure first with adaptable boxes or metal consumer unit enclosures. Then after cable  preparation, I offer up the S.W.A. cable and lastly tighten the S.W.A. gland back nut to secure the armour. This way the back nut is easily secured external to the enclosure, and the earthing nut is rock solid.


    Z.


  • Just to go back to the OP's actual cable size - he says the diameter of the cable is 23mm - Too small for 2 core 25mm csa SWA surely?

    No indication of actual length of cable run - still too many imponderables.
  • Just to go back to the OP's actual cable size - he says the diameter of the cable is 23mm - Too small for 2 core 25mm csa SWA surely?

    Larger SWA cores often look a bit small to me - I suspect they have thinner insulation than insulated & sheathed singles.


    Cleveland actually quote even smaller for theirs - 20mm for 2-core 25mm² and 23mm for 3-core. https://www.clevelandcable.com/media/pdfs/BS5467-PVC-mains-and-control-cable-25mm-to-400mm.pdf.

       - Andy.
  • Former Community Member
    0 Former Community Member
    Hi.. The length of the swa cable is 24 meters


    Thanks 


    Dave