Spur off a spur?

Discussion in 'Electrics UK' started by Spreadie, 8 Jul 2005.

This topic originated from the How to page called Extending a ring circuit using existing sockets.

  1. Spreadie

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    My house is 50 odd years old and, apart from the kitchen, there is only one socket(single or double) in each room. Now the double in the sitting room is supplied thru the wall from what looks like an unfused spur under the kitchen cupboards.

    I intend to replace the outlet in the kitchen with a fused unit. But I want more sockets in the sitting room.

    Now as I understand it (feel free to correct me) if the original spur is fused, I can add a number of spurs to it. If I can do this should I group the additional spurs together as a 'mini ring' feeding back to the fused spur? Or am I just as well daisy-chaining the spurs off the fused spur?

    Tis an old concrete house and I can't find an accessible ring downstairs. And I know you're not supposed to extend a ring downstairs from the upstairs circuit.

    Any help is gratefully received.
     
  2. andy

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    just connect them as a radial, since its fused down at the FCU. however, this means you only have 13A to play with for everything in your sitting room. have TV etc on and plug the hoover in and i might blow the fuse
     
  3. comms

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    Nothing wrong with extending an upstairs ring to downstairs, so long as you note it on consumer unit protective device labling & dont go above the max area coverage allowable for a ring main.

    Yes if the outlet in the kitchen is changed to a fused connection unit, you can add a number of outlets to it as a daisy chain as you put it (radial), but remember they will all be protected by the 13amp fuse in the fcu not to handy if your running a few high powered items at once & fuse goes.

    Before doing any of the above check that you do have a ring final circuit & not a radial, because if its a radial circuit it will make life easier, you could then just extend from the outlet in the sitting room to new outlets.
     
  4. Spreadie

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    Thanks for the fast replies chaps.

    Obviously being a sitting room there is a TV, Sat box, DVD, Hifi, video and a couple of table lamps. I have had to make do with a 6-way fused/surge protected extension up until now. Needless to say, its not the most desirable solution.

    Despite the fact I haven't blown anything yet, I imagine adding a radial might not leave a great deal of headroom for any addtional appliances (not that I plan to add many more)

    Would you suggest extending from the upstairs ring as a better option?

    Thanks again
     
  5. andy

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    or even extend the ring from the kitchen where the existing spur is connected
     
  6. Spreadie

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    Can't get to the kitchen ring - The missus wont let me - would have to dismantle the fitted kitchen and remove a lot of tiles.

    Life would be so much easier if she just didnt care

    +++++++++++++++++++++

    Just re-read that and I dont understand. Whats a ring final circuit? And does it make a difference to the max amps I can have on the sitting room circuit? I unscrewed the soon to be fused socket under the kitchen cupboards and it only has one twin and earth cable going to it - so its a spur right?

    Also slightly OT - I noticed that cables give a max rating in free air - will this change significantly if I am running the cable thru plastic conduit inside the walls?

    Thanks
    __________________
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    please note 10a
     
  7. PowerTool

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    "Ring final circuit" is the correct term for what is commonly known as a "ring circuit" - the popular way for wiring household sockets.

    If there is only one cable going in,it could be a spur,but it could also be the last socket on a radial.
    What size fuse/mcb is it on? (Rings normally 30/32A,radials 16/20A)
     
  8. comms

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    Radial could have 30/32amp fuse/mcb if wired in 4mm twin & earth.

    To check if it's a ring at the fuse/mcb you will have two wires going to the fuse/mcb( just to confuse so could a radial),so isolate the consumer unit then remove both wires from fuse/mcb, using a multimeter check for continuity between the two wires, if you have continuity you have a ring main (ring final circuit).
     
  9. Spreadie

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    Thanks for the replies.

    Had a battle royal with the assistant in the B & Q Elec Dept, he was swearing blind that I could not have more than 2 sockets on a spur/radial regardless of wether it is fused or not. He then went to great pains to explain that I could extend a ring from the spur!?! What a comfort that chaps like him are there to advise the public.

    By the way I have decided to extend the upstairs ring down into the sitting room, methinks I will need a few more stone cutting blades!

    Thank you all for your advice.

    Spreadie
     
  10. ban-all-sheds

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    I think I know him...
    [​IMG]
     
  11. comms

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    Ban
    Quality lmfao
     
  12. felix

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    I wonder whether this is what he had in mind ---

    If that kitchen socket is a spur direct from a fuse in the consumer unit and is wired with 2.5mm cable (or bigger) you can extend it into a complete ring. You can add as many sockets as you like as long as you finish back at the fuse.

    The hard part is finding out exactly how that kitchen socket is wired. I would do this anyway because somebody has already spurred off a spur. If you find one bodge there may be more.
     
  13. ban-all-sheds

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    That would be a radial circuit, not a spur, and a 2.5mm² radial would be fused at 15/16A, or possibly 20A, so what good would it do you to turn it into a ring final?
     
  14. felix

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    Fair point; I left out a lot of fine detail. IF it's a radial wired entirely in 2.5 sq mm (or bigger) and IF it doesn't have any side branches - or at least none bigger than one item - then it can be continued onwards round extra sockets and back to the consumer unit to form a ring. The fuse can then be (optionally) increased to 30 amps.

    Spreadie, those details are important. You'll need to know exactly how that kitchen socket is wired to start with.
     

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