This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

CU replacement

Former Community Member
Former Community Member
What testing should be undertaken when replacing a CU?
Should the property have a EICR before the replacement is carried out?

  • Legal minimum, on completion, before energisation, it should be checked to be safe .


    To BS7671, expect a set of tests results for each circuit for IR and either R1+R2 dead test, or maybe the Zs before it was turned off, and some notes about wire sizes suitable for the breaker that protects them.


    It is not a regs requirement, but in reality to do some sort of check before removing the old one is a very good idea, as it saves time afterwards trying to fault find with the power off. Especially true if RCD protection is being extended to circuits that did not have it before, as there is a tendency for this to reveal hitherto unknown issues that mean with the new board you cannot get the RCD to stay on. Typically it all works just fine until it fires off at 5 o'clock on a Friday, or after lunch on Saturdays, just after you have put all the tools back downstairs in the truck.
  • Have a look at Best Practice Guide 1 by Electrical Safety 1st, it's all in there with handy flow charts at the back:
    https://www.electricalsafetyfirst.org.uk/professional-resources/best-practice-guides/


    Also see guide No 4 re EICRs.


    F
  • This begs the question, "why do you want to change the CU? Surely it must be on the recommendation of an EICR.
  • Chris Pearson:

    This begs the question, "why do you want to change the CU? Surely it must be on the recommendation of an EICR.


    Consider a homeowner who looks at their rewireable fuse board and wants a consumer unit, with CBs, just like they've seen elsewhere , so they don't have to fiddle with bits of fusewire - and don't know anything about eicrs.


  • I always insist on doing an EICR prior to CU change. It`s only fair both to me and the customer
  • Farmboy:
    Chris Pearson:

    This begs the question, "why do you want to change the CU? Surely it must be on the recommendation of an EICR.


    Consider a homeowner who looks at their rewireable fuse board and wants a consumer unit, with CBs, just like they've seen elsewhere , so they don't have to fiddle with bits of fusewire - and don't know anything about eicrs.




    If it's that ancient, is the rest of the installation likely to be satisfactory? Best to know in advance if a complete rewire is required!


  • Former Community Member
    0 Former Community Member
    The current consumer unit is not that old, the property was rewired in 2003

    The reason for change is damage to the CU plastic case  (it’s the older split type with one RCD) plus the meter tails are 16mm T+E   
  • Well then, an EICR is overdue. Much of the inspection and testing will have to be done in the course of installing the new CU, but most of it doesn't have to be done twice. If you have the EIC for the re-wire, so much the better.
  • ebee:

    I always insist on doing an EICR prior to CU change. It`s only fair both to me and the customer


    Exactly as ebee says.  An EICR is a snapshot in time. The greater the period elapsed the chance that something has changed increases. If for example, it is a "distress change", then perhaps go ahead and inspect/ test as is needed, but for your own protection do a Report first. Things that are a deal breaker you do not want to deal with once you have ripped the old one out. You are then at the point of no return.


    Perception is everything in contracting and whispers become "fact. Many customers view a Consumer Unit change as a cure for all ills, many then presume the whole install is "new" and all sins have been "absolved". At the end of the day the same erroneous perception can be derived by simply replacing all the accessories for new ones........builder stylee. The murky part of the electrical industry uses a new CU as a whitewash for a badger install, very much the case in rental for example.


  • "whitewash for a badger install" In 2020? surely not!


    Regards. UKPNZap