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16mm SWA cable terminating at Consumer Unit ?

Discussion in 'Electrics UK' started by andemz, 28 Jan 2005.

  1. andemz

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    Hi all,

    I have 4 core 16mm SWA cable which is running at a length of 25 meters from consumer unit to extra big garage. We have a plan to maybe one day turn this into extra accommodation etc, which will run combi, ring circuit and a couple of light circuits, alarm.

    16mm is big but i thought bigger is better.

    Anyway how would you advice on the termination to the consumer unit. Could i gland into a weather proof box and then come into the consumer unit with a small cable? If so what size cable would you use and if 4 core what color wires would you use for Live neutral and earth. what would you do with the 4th wire. The colors i have are red yellow blue and i forget the other one.

    I will put this on a 45amp breaker non-rcd side of the unit.

    Can you please advise.
     
  2. AliasOmega

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    I wired my uncles garage not so long ago, i used 6mm 3 core SWA put on a 32amp mcb. I used a waterproof box on the outside of the house, and then 6mm into the fuse board running a seperate 4mm earth with it as the earth in the 6mm was only 2.5mm.

    I used the red as usual, put black tape on the blue.. (neutral) and the yellow in earth tape for the (earth). With the 4mm connected with the 2.5mm earth this gave me 6mm live, 6mm neutral, 6.5mm earth (for example). I put a RCB board in the garage, and on the un-protected side in the house as i did not want it tripping the whole thing out.

    The garage only has 4 double and a few lights, and a motorised door..but better to build for more now than later.




    The 4 core cable you have will be red. blue. black and yellow. I would terminate into a waterproof box & use the red, black & yellow with earth tape on it. I would leave the spare cable (blue) at the back of the box unconnected. Remember to earth the sheath of the cable incase anyone tries to dig it up. You could use 6mm cable onto a 32amp mcb if its easier to change the cable later in life...if its hard to change the cable from the waterproof box - consumer unit then put maybe a 10mm, maybe even a 16mm T&E with a seperate earth.

    You could use 16mm all the way, and limit it too a 15 / 20 / 30 amp mcb...


    Alias
     
  3. felix

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    I'm not sure I fully understand all the questions here. When you say "advice on termination to the consumer unit" do you mean the new one you're going to fit in the garage because you begin buy implying that this cable is already connected at the house end.

    Red, yellow and blue means it's three phase cable. The other one is probably black for neutral. Unless you really do have three phase power (highly unlikely, count the wires coming off your meter) it means that somebody has used a spare piece of cable they just happened to have lying around instead of buying the proper stuff. It's not dangerous in itself but it is confusing as you've just discovered. In particular, the earth wire should be instantly identifiable and it isn't. There's a potential danger there for some future owner.

    If it's already connected you'll have to open the consumer unit and see which colour goes where. If not then I suggest red for live (obviously), black for neutral (if you have it, otherwise blue) and yellow for earth but sleeve it in regulation green/yellow. The remaining one should be cut back and both ends insulated. Don't forget to earth the armouring as well. When somebody puts their spade through it you want them to hit earthed metal first.

    On a 45 amp circuit you want 10mm cable from the gland box(es) to the consumer unit(s).
     
  4. andemz

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    No the cable isn't conected up either end to the consumer units.

    I will not be doing the consumer unit end as i am having a sparky to do that for me.

    I will have a look at the cable colors and let you know what they are.

    Because all of my wiring is in harmonised colors and i got this cable some time ago, i think i will connect the 16mm cable to the 10mm cable in a weather proof box with the 10mm cable being harmonised colors for ease. All of the cabeling in the outbuilding will also be harmionsed colors and so i will label at each end of the consumer unit that the cable laid under ground is not harmonised.

    Actually what i have done is created a diagram for future owners of all of the junction boxes and locations along with every plug, underfloor heating controls, lights and fused connection units. This will be for ease if they ever want to add etc.

    How would you suggest earthing the armoured part of the cable?
     
  5. AliasOmega

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    You get a little metal frying pan looking ring that goes on the gland between the plastic / metal box. Take a looped crimp and bolt is too it through the plastic, and apply to the earth connection.

    You could do it on one end, as the cable carries a earth, but its up too you. I would do it both for ease..
     

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