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Recommended checks before CU change

Former Community Member
Former Community Member
As most of you know I’ve only been qualified for just over a year and I’ve got a quote to do for a cu upgrade.


I know I’m nowhere experienced enough to do EICR’s yet, but what would you guys recommend I check/test before doing the cu upgrade and should I do these checks/tests at the quote stage?
  • 0

    Tillie:

    Do ring circuit continuity at a convenient socket.




    Tillie, loads of practical advice with which I agree, but if you have the fusebox cover off, why not do the ring tests from there?


    I might add that I cannot remember being taught on my course that rings could be tested at any point, but it is occasionally easier than in the CU where the tails may be short or at the back.


    Then again, if you open a socket and find that it's a spur, it's back to plan B. ?

  • 0

    Chris Pearson:


    I might add that I cannot remember being taught on my course that rings could be tested at any point, but it is occasionally easier than in the CU where the tails may be short or at the back.


     



     




    I have seen that method in one of the NICEIC's training videos, as you say useful when all the cables are tucked behind the CU and it is not easy to identify each leg of the ring.

  • Former Community Member
    0 Former Community Member
    Hi , it is a lot easier to do at a socket and perfectly acceptable.


    On an old installation like the one in the picture you will generally find that the existing old sockets are on a ring.


    Just be careful of additions where spurs are taken from spurs , in this case you could either rectify at further cost or drop mcb to 20a.


    Also with no Rcds present and sensitive gadgets removed you could possibly carry out IR for the whole board at the same socket as your ring continuity test.


    I think we can only do so much before a board change and as long as the installation is not dangerous then just get on with it.


    You may have a few slightly low IR readings but not dangerously low , the installation will be a lot safer than what is was.


    Someone else will do it regardless.


    Regards
  • 0
    I do carry out ring final continuity tests sometimes at sockets if it is easier, especially if the consumer unit is at the back of a kitchen unit or otherwise difficult to access and work on. Recently during an E.I.C.R. test I took off a socket to undertake tests and found it was a spur run. I then took off another socket and found that that was supplied by a spur from the ring, all old and original sockets it seemed. So I took off a third socket and found that that was on a spur as well. This was in a 50s/60s bungalow. It appeared that the ring ran in the loft and most of the sockets were run as spurs below the ring. I made a comment on the paperwork covering the situation.


    Z.
  • 0
    Well Zoom I have seen a few times a ring with no sockets then each socket is on a spur via a JB from that ring.

    Not the most elegant of solutions and breaks with recommended practice of no more points on spurs than points on ring, but no worse than any spur on a ring on a 30/32A OPD all told.
  • 0

    Fitzy71:

    Thanks guys


    the homeowners said the house was built in the early 70's, they do however have loads of class I light fittings.


    If there is NO cpc for the lighting circuits, I can't reconnect them to the new cu, especially if they refuse to replace all the class I with class II fittings, so what do you do in that scenario?


    But considering they've had new lights fitted previously, especially the loft and 2 small lights at each side of the master bed, I'm guess there IS a lighting cpc present.....




    Perhaps unwise to guess or assume anything. A lady asked me to look at her lighting cct that was blowing fuses. Upon inspection i told her it had no cpc. She said i know, last year i had a metal chandelier installed, and the electrician who fitted it said there was no earth wire but not to worry because the light is on the ceiling so you're not likely to be touching it anyway. Hmm.


    On a different note, reading through the replies, there's a difference of opinion about the depth of testing to do. While all seem to follow the same sequence of continuity of protective conductors, ring cct continuity, IR testing, etc, some favour the depth of initial verification testing, others use periodic I&T methods.


    F

  • 0

    ebee:

    Well Zoom I have seen a few times a ring with no sockets then each socket is on a spur via a JB from that ring.

    Not the most elegant of solutions and breaks with recommended practice of no more points on spurs than points on ring, but no worse than any spur on a ring on a 30/32A OPD all told.




    Hello ebee,

                          I would rather initially connect up new sockets at floor level than struggle about in the loft in the dark with junction boxes spurring off the ring for sockets below. Still them be strange ways in the cuntrysoide boy.


    Z.

  • 0
    Hi Zoom,

    not aways drop fed from loft/1st floor but under floor then up to the points too. Crazy methinks but have found them like that.
  • Former Community Member
    0 Former Community Member
    Thanks for all your replies guys, been very helpful.


    What would be a low enough IR reading to cause RCD’s to trip on a new board?


    The house in question is a four bedroom country house, so if I can avoid it, I’d rather not have to go around the whole place disconnecting everything, the residents are both in their late 60’s.  I didn’t see a circuit diagram on my initial visit either, so it could be a fun visit anyway.  I do need to find where their water & gas enters the property too, as I couldn’t see any bonding from the fuseboard and the lady wasn’t sure where they both were.
  • 0

    ebee:

    Well Zoom I have seen a few times a ring with no sockets then each socket is on a spur via a JB from that ring.

    Not the most elegant of solutions and breaks with recommended practice of no more points on spurs than points on ring, but no worse than any spur on a ring on a 30/32A OPD all told.



    I have a rewire to do where the current arrangement appears to be a ring for the first floor sockets and spurs to the sockets below. If I am lucky, the cable drops will be capped and it may be possible to pull new ones up whilst extracting the old ones. However, it seems unlikely that both legs of a ring could fit into the available space. Time will tell!

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