Help for an amateur

Discussion in 'Electricians' Talk' started by Richard Murray, May 16, 2022.

  1. Richard Murray

    Richard Murray New Member

    I've got an issue with the new electrics in the garden office I built. Can anyone help me understand the problem?

    2.5mm 3 core SWA cable feeds the office from the RCB in the house.
    CU in the office has 6A and 32A breakers - 6A for lighting circuit, 32A for the socket ring (4 double sockets)

    upload_2022-5-16_21-44-20.jpeg

    The armour cable comes into the box above the earth, and has yet to be connected in this photo. But then the sparky did connect it (black to earth, grey to neutral and brown to live) strange things began to happen.

    Firstly the socket ring tripped the house RCB without any load applied. So we disconnect the sockets either side of the CU on the ring to try to isolate. Breaker now does not trip. We start with the left hand socket and test L-N on both feeds and find one with 235V L-N. So am I right that this must be the leg which connects the socket and the CU, and that it cannot be compromised? But...nothing will work in the socket. Exactly the same happens at the socket on the right side of the CU.

    Why can power reach a socket, yet the socket won't power anything, including a working 3A lamp?

    Sparky is scratching his head, and can't explain to me what the issue is...

    Any help gratefully received.

    R
     
  2. tinkerbell60

    tinkerbell60 Member

    That looks a very rough installation, the armoured is not terminated correctly. Get your “sparks” back to correct the faults and test the installation, then your problems will be solved.
     
  3. chesterw

    chesterw Well-Known Member

    For a start, you need a new electrician, the main neutral is not connected, the ring circuit neutrals are incorrectly connected. And why is all that earth pvc tape wrapped around the incoming cable.
     
    BiancoTheGiraffe likes this.
  4. Hausfix

    Hausfix Screwfix Select

    I can’t see a live busbar that connects the live output from the main switch to the live inputs to both of the MCB’s.. normally you’d see a brass metal strip that runs from the bottom screw of the live side of the main switch to the bottom screws of the MCBs
     
    BiancoTheGiraffe likes this.
  5. BiancoTheGiraffe

    BiancoTheGiraffe Screwfix Select

    Richard, did you do this yourself?

    No problem here if you did, but it's best to own up ;)
     
    Jiml86 and chesterw like this.
  6. Richard Murray

    Richard Murray New Member

    Cheers - tinkerbell60 - the swa needs a gland to correctly terminate?
     
  7. Richard Murray

    Richard Murray New Member

    Was thinking just that -
    "Sparks" is my wife's uncle who thought he was doing me a favour... before I get someone in I want to try and understand the 'damage'.
     
  8. Richard Murray

    Richard Murray New Member

    Thanks - busbar was connected when we had the issues.
     
    Hausfix likes this.
  9. Hausfix

    Hausfix Screwfix Select

    ‘Damage’.. don’t you mean ‘Danger’?
     
  10. Hausfix

    Hausfix Screwfix Select

    A gland will also allow you to make an earth connection to the steel wire that surrounds the inner cables, gives you a better chance of the RCD tripping if cable gets damaged..
     
    Richard Murray likes this.
  11. Coloumb

    Coloumb Screwfix Select

    What size breaker is that lot fed from? The swa gland needs to be readily accessible so you're going to have to move that CU.
     
    Richard Murray likes this.
  12. The Happy Builder

    The Happy Builder Screwfix Select

    When you measure 235 volts between two conductors it doesn’t mean they are actually wired correctly and polarity is correct, a bit more testing is required to find out if they are actually wired correctly.
     
    Richard Murray likes this.
  13. Richard Murray

    Richard Murray New Member

    40A on house RCB. It is not supposed to be powering much, just 2 Led batten lights and laptop/printer/monitor etc on the sockets.
     
  14. Coloumb

    Coloumb Screwfix Select

    40a feeding a 32a breaker with 2.5mm is very dangerous situation. You risk an overload that could overheat the cable and start a fire. You will want to get this whole mess sorted asap. Just get a spark in to sort this out. Mostly it will want stripping out and starting again.
     
    Richard Murray likes this.
  15. The Happy Builder

    The Happy Builder Screwfix Select

    The MCB in the house needs to swapped for a B20 MCB, the socket ring in the office CU might as well be swapped for a B20 as well, but it’s not really needed and is little more than a switch as is just duplicating the other one in the house.
     
  16. Richard Murray

    Richard Murray New Member

    My mistake 6mm cable - but even so - I take your point that it all needs to come out and that a professional needs to come in. Thanks
     
  17. adgjl

    adgjl Screwfix Select

    It would help if you can post photos of the test certificate your “electrician” handed you. We will then be able to see what (if any) testing was carried out. Fitting a new consumer unit requires notification to the local council under building regulations, unless your “electrician” was a scheme member.
     
  18. Hooper

    Hooper Member

    I'm no electrician but from the other posts it seems there are multiple issues so it needs taking apart and doing again. A qualified electrician can issue a certificate as well covering you for Building Regs
     
  19. Bazza-spark

    Bazza-spark Screwfix Select

    Not unless he is registered with a scheme.
     
  20. Tony Goddard

    Tony Goddard Screwfix Select

    Sweet baby Jesus thats a mess and no mistake.

    that mini CU needs to come out and be re-done.

    some testing will isolate the fault causing it to trip, the continuity and insulation resistance of the final circuits should hve been tested before it was connected. It could be a wiring fault, or a screw through a cable, either way testing will find it.

    I can only assume your wife's uncle is not an electrician by trade or else he would have done a much better jonb and been able to find a fault with what must be a very small circuit!

    He should have completed an EIC (Electrical Installation Certificate) in which there is a page to list the results for each circuit. He should also have notified the work, either to his scheme (NICEIC, NAPIT etc etc) or direct to LABC to comply with part P - even if he hasn't done that part (in which case you, not him have broken the law, you've got to love the law, complex stuff! - I'm not a lawyer or a moral arbiter, thats your concern, as an engineer I'm just interested in the safety aspects) he should have done the EIC confirming everything is tested correctly.
     

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