2.5mm light circuit cable - illegal in this case?

Discussion in 'Electricians' Talk' started by db1819, May 21, 2019.

  1. db1819

    db1819 New Member

    Hi,

    I have a problem where during the re-wiring (which is still ongoing) a possible mistake was made.

    The upstairs light circuit is done in the following way

    Consumer Unit -> 2.5mm cable -> "Surewire" 6 Way Junction Box -> 1.5mm cables -> 5 radial circuits to light switches and lights

    The electrician who will be signing off the certificate said this is not correct and the 2.5mm cable absolutely must be changed. It can still be changed but will require some effort to run it as some areas are no longer accessible and have been dry walled so I would like to avoid changing it if at all possible

    While I understand that that the correct cable would be 1.5mm however I cannot understand why having a bigger cable in this case would make the installation illegal. Is he just being pedantic in this case or is there a safety concern?
     
  2. Hans_25

    Hans_25 Screwfix Select

    I can't see how a bigger cable can be an issue - ask your spark to explain why it is an issue and has to be changed.
     
  3. Coloumb

    Coloumb Screwfix Select

    2.5mm should be fine so long as the breaker is <= 10a. In fact it's actually quite a good idea as it will help with volt drop. Personally I would say that he must have some other reason for insisting on this as no spark in his right mind would get busted up over the cable size being too big. Are you 110% certain this is what his concern is and not something else you haven't told us or not understood? What's the back story? Why is he filling in a cert for someone else's work?
     
    Last edited: May 21, 2019
  4. Hans_25

    Hans_25 Screwfix Select

    What rating breaker/MCB is that circuit on?
     
  5. db1819

    db1819 New Member

    He explained that the lights must always be on 6A breaker and that 2.5 cable should never go on the 6A breaker. He also mentioned something about the stuff in regulations that govern testing of circuits where the 2.5 cable would give off different readings etc, I didnt really understand that.
     
  6. db1819

    db1819 New Member

    Its not yet connected to any breaker as the consumer box has not been fitted. Its coming up to the time of fitting the consumer unit and after he inspected everything this was his only concern. He said no matter what, that cable must be changed from 2.5 to 1.5 for sign off
     
  7. Coloumb

    Coloumb Screwfix Select

    But WHY is he issuing the cert? Is this your own re-wire that he is certifying?
     
  8. db1819

    db1819 New Member

    His reasoning was that lights should always be on 6A breaker and the cable size must be 1.5mm. He also said something about if it came to fault diagnosis the 2.5 cable would cause issues. He initially visited the site and gave specific instructions on how to run the cables to one of the workers who is an electrician but does not have the full qualification of writing certificates out. So this worker done all of the re-wiring and now came the time to fit the consumer box which the guy who will write the certificate wants to do himself. He inspected everything and is only not happy about this 2.5mm cable. The rest he said is as per legislation.
     
  9. Coloumb

    Coloumb Screwfix Select

    So does the "spark" who did the install, does he work for the spark who is issuing the cert? If not, what is their relationship?
     
  10. db1819

    db1819 New Member

    He is issuing certificate because all the old wires have been completely removed in the house, and one of the workers that he recommended did complete re-wire of whole house to his instructions. The man who will issue the certificate recommend this worker and the worker made this 1 mistake. The rest of the wiring is correct according to the man who will issue the certiciate. But he said he will not move on with the fitting of the consumer unit until this cable is changed from 2.5 to 1.5. This is causing great confusion to me also as I cannot understand why having a bigger cable could be unsafe in this case
     
  11. db1819

    db1819 New Member

    Relationship is the man who issues certificates has a number of workers working for him, they do fitting to his instructions. He then comes in to do checks as well as doing the final fitting of consumer box and connection himself. He also writes certificate out in the end where as the workers do not have such qualifications from what I understand. They only work to his instruction.
     
  12. Hans_25

    Hans_25 Screwfix Select

    1. I can see no issues in having a 2.5mm cable on part of the lighting radial if being fed from a 6A MCB. The MCB is there to protect the wiring, so a 6A MCB is fine for 1.5mm and above.
    2. Was this fixed price? On what basis was the work performed? If fixed price then it should be remediated at the trade's expense.
     
  13. Coloumb

    Coloumb Screwfix Select

    Look I don't know if I'm missing something blindingly obvious here but who cares? It's not your problem. Get the "spark" who put it there to either argue the toss with the spark who employed him or get him to replace it. I can't really see why this is something your even worrying about.
     
  14. db1819

    db1819 New Member

    It will involve damaging some of the plastered/painted walls and causing other delays so I really dont want to do it, especially since it also does not make any sense. But I guess if I will not get my certificate without doing this, there is no other way..... I'm just fed up with all the delays we had already.
     
  15. Coloumb

    Coloumb Screwfix Select

    Well then I can only suggest you get in touch with who ever he is registered with and take it up with them, though I don't know if that will take as long to sort out as it will to pull out the cable and replace. I can't see there are any other options tbh, if your spark has made up his mind and won't budge.
     
  16. Hans_25

    Hans_25 Screwfix Select

    If he screwed up, then he should make good, simples.
     
  17. Rulland

    Rulland Screwfix Select

    You can run 10mm twin and skin to your lights if you wanted too, undersized is a problem, oversized is not:cool:
     
  18. Mr Rusty

    Mr Rusty Screwfix Select

    I think a little thought to the contractual relationship is needed. If you instructed the spark, and HE instructed the helper who did it wrong (according to him), then the problem is his, and he is responsible not only for the cost of the replacement cable, but also your consequential costs - the extra cost of re-doing all the plasterboard etc. If you incur other costs through delays arguably you are entitled to recover compensation for that too. If you instructed a builder and he instructed the spark, then it is the builders problem. This is possibly a prime example of works going ahead without at least the bare bones of a contract in place.
     
    longboat and Hans_25 like this.
  19. peter palmer

    peter palmer Screwfix Select

    Must be loads of industrial lighting wired in 2.5 on 10A breakers, how does he feel about 4mm socket circuits?

    We wired some driveway post lights on a very very long drive once and started with 10mm SWA for part of the run ending up with 1.5 for the last few.
     
  20. goldenboy

    goldenboy Super Member

    More going on here I think.

    Why would the guy not sign off his mates work? Especially if as all you say there isnt a problem with it.

    Are there any payment issues? Or perhaps some work was done by A.N.Other without the agreement of original fella. Any other issues on job?
     

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