extending ring circuit

Discussion in 'Electrics UK' started by panza, 3 Jan 2011.

  1. panza

    panza

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    Can anyone tell me if extending an existing ring circuit needs to be done by a qualified electricitian (who can self certify) or is notifiable under building regs? or can it be done by a competant DIY'er?

    The existing ring circuit is on a B32 MCB, 2.5mm2 cable with 5 double sockets + 1 single socket. I want to extend it to have an additional 3 double sockets.

    Don't know the overall length of the ring, but it is quite long as the sockets are at the back of the house and the CU by the front door.

    In addition to the query above, I have also discoved that the existing mono pitched roof over my kitchen does not have insulation. I have pulled down the ceiling and am going to be installing insulation between and under the existing rafters. The majority of the existing cabling (with the exception of some juction boxes) will be within the 70mm ventilated void above the new insulation, however the cables will need to drop through the insulation where the ring circuit drops down at the walls and also at the lighting rose postions. Is this acceptable?

    Thanks
     
  2. ericmark

    ericmark

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    Part P only requires one to pre-notify the LABC where additions are fitted outside, In kitchens, and in bathrooms. Although you could do the work where you need to notify it will be likely cheaper to get a member of a scheme to do the work.

    Part P is law but BS7671 can be quoted in a court of law to show negligent workmanship etc but is not law itself. However not to comply would be silly and you mean if anything when wrong you would have a problem.

    Under BS7671 you should test the ELI to ensure it is not too long. If you don't know what ELI is then you are not competent.
     
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  4. panza

    panza

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    Thank eric. The ring services the kitchen so I will appoint an electrician who can self certify.

    I do know what ELI is hence why I mentioned the ring length in my initial post.
     
  5. ericmark

    ericmark

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    I think the LABC charges are silly and likely that is best option. The 17th Edition introduced RCD on all sockets under 20A and lifted the volt drop from 4% to 5% so that has added about 20 meters to the permitted length of a ring main.
    However many electricians in the past did substandard work and it is all to common to find the system can't even support the sockets it has never mind adding more.
    The amendment 1 it seems is going the reduce the requirements for fitting RCD's and it seems likely one will not have to add them to an existing circuit. But likely there will also be some down side like reduced ELI.
    I am sure in the past we all fitted sockets without testing and in the main we got away with it. But today people are all too willing to point the finger of blame and taking a chance is no longer worth it. And really that is a good thing.
     
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