RCD issue

Discussion in 'Electricians' Talk' started by Luke Easthope, Dec 15, 2023.

  1. Luke Easthope

    Luke Easthope New Member

    Hi, wondering if anyone could help me please.

    I've installed a new consumer unit in my house. Upstairs lighting, sockets and central heating all working no problems protected by RCD. Downstairs lights, utility ring main, lounge ring main and cooker all work fine until 2nd RCD installed to protect downstairs, all work with no load, then with minimal load RCD trips.

    So far I have tested/checked lighting circuit, lounge ring main and utility ring main as well consumer unit connection as well as every socket. I can't seem to find the problem. Like I said all work without the introduction of the 2nd RCD also checked the RCD to make sure it wasnt faulty still same issue...

    Any advice would be greatly appreciated even if its something obvious I'm missing please and thankyou!
  2. Ind spark

    Ind spark Screwfix Select

    Any pictures?

    Simple things to look for, neutrals in the correct bar, borrowed neutral on the up and down lighting circuits
  3. WH55

    WH55 Screwfix Select

    What tests have you done ? Do you have the equipment to do an IR test on these circuits ?

    In addition to what @Ind spark says, you may need to start opening up each accessory / socket front / cooker plate etc., and checking each of the terminations.
    Ind spark likes this.
  4. Bazza-spark

    Bazza-spark Screwfix Select

    Er, you do realise this work in notifiable under Part P of the building regs?
  5. MGW

    MGW Screwfix Select

    I when no RCD is fitted start with the clamp on ammeter. The diffrence should not exceed 9 mA.

    Cooker, immersion heater, frost free freezer uses mineral insulated heaters, and these are well known for absorbing mosture from the atmosphere, the on/off switch often does not switch neutral, so testing with insulation tester neutral to earth can often find faults missed testing line to earth, I would just use 250 volt setting I know should use 500 volt, but that could give wrong reading if there are any SPD fitted.

    I am assuming you have the equipment when doing notifiable work?
  6. Bazza-spark

    Bazza-spark Screwfix Select

    There is a member on here who is an absolute stickler for the law. He will report you to the Part P police. They will come and arrest you then take you to the Tower of London where you will be flogged to within an inch of your life (I don't like metric), then you will be paraded through the streets with a hat saying "I failed Part P notification."

    Then you will be sent to a dungeon for 6 months :D
    Last edited: Dec 15, 2023
    techie, WH55 and Ind spark like this.
  7. Ind spark

    Ind spark Screwfix Select

    Obviously not o_O
  8. The Happy Builder

    The Happy Builder Screwfix Select

  9. adgjl

    adgjl Screwfix Select

    What testing have you done?
    Are you an electrician or a diyer out of their depth?
    What test equipment do you have?
  10. Coloumb

    Coloumb Screwfix Select

    Why are you telling him this? In the other thread you told to op to ignore me when I told him his diy work was illegal and that I was wrong becuase I don't work as a "professional spark".

    Under Part P you know of a law that says it's different to replace a CU without notifing than there is for a registered spark to notifiy work he didn't do?
  11. Bazza-spark

    Bazza-spark Screwfix Select

    I told him to ignore you because your advice was contradictory to that given him by his pro sparky.

    Part P requires the notification of a consumer unit replacement in domestic properties whoever does it. The difference being if it is done by a registered spark then it can be done after the work is completed. If it is an unregistered spark or DIYer then it must be notified in advance and the appropriate fees paid unless it is an emergency, as you well know.
    Last edited: Dec 15, 2023
  12. Coloumb

    Coloumb Screwfix Select

    The advice I gave him was correct. Anything his spark tells him is completey irrelevant. It is just as illegal for a registered spark to certify work he didn't do as it is for a DIY'er to fit a CU with notifying BC first. There is absolutny no difference between the two. You are breaking Part P of the building regulations law in both cases.
  13. adgjl

    adgjl Screwfix Select

    Please take your argument back to the thread where it started, instead of trashing a new thread as well.
    WH55 and Bazza-spark like this.
  14. Bazza-spark

    Bazza-spark Screwfix Select


    I'd rather he just shut up.
  15. Wellwisher

    Wellwisher Well-Known Member

    Notifiable yes, but nothing to do with part P which says work must be safe.
  16. Bazza-spark

    Bazza-spark Screwfix Select

    Not notifiable in industrial, (where I worked) as Part P doesn't apply, but in domestic which it does. And Wales has different rules to England as our reg didn't change.
  17. Wellwisher

    Wellwisher Well-Known Member

    This is part P. That's it. Nothing about notification. Nothing about part P qualified.

    Attached Files:

  18. The Happy Builder

    The Happy Builder Screwfix Select

    Try reading page iv.
    Bazza-spark likes this.
  19. Bazza-spark

    Bazza-spark Screwfix Select

    Don't want to argue, but I never mentioned Part P qualified and this is a direct link and quote from the official page.

    To be honest, I don't care whether he notifies it or not, I was just pointing out the fact.

    Being retired I don't do any of it any more anyway.



    Look at the actual reg, not a clip.


    I'm morphing into him!
    Last edited: Dec 15, 2023
    techie likes this.
  20. MGW

    MGW Screwfix Select

    Oh so if I install a distribution unit instead of a consumer unit it's then OK?

    The only time when there is a problem is when some one is injured. Hospitals are required to notify with an electric shock, and I have had the HSE inspector visit as a result.

    But when I wanted copies of the completion certificate I was told it would take 4 months, so there is little chance of solicitors checking if a completion or compliance certificate was issued.

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