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Obvious departures from the regulations at first glance at a new consumer unit.

Jaymack
I was asked to give an EICR on an domestic property which is to be placed on the market (part P applicable). I found that a builder as part of the other renovation work, (new doors, windows and kitchen etc.) has carried out the installation of a new metal consumer unit. On first opening this dual RCD unit, the 2 lighting circuits were on one R.C.D., and the 2 final ring circuits on the other R.C.D,, it was obvious also, that some wires to the new CB's were short and not lengthened, resulting in a bird's nest at the M.C.B.''s.


Plainly, a qualified electrician hadn't carried out the work. What would the readers as registered electricians have done ?. 1. Walk away. 2. Propose to have an E.I.C.R. carried out (UNSATISFACTORY), then carry out the rectification work and issue MWC's.3. Rectify the obvious departures, issue M.W.C.'s and then issue a SATISFACTORY E.I.C.R. 


Jaymack
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    Sorry, I should have have said that there are 8 circuits involved here, not just a lighting circuit for downstairs and another for upstairs, ditto for the 13A sockets. The only reason I can think of behind the irrational mix, was that the cables were simply too short and should have been lengthened; this is a basic departure from the regulations.


    I am surprised and saddened, that there some who think that it is OK to have this arrangement on a dual RCD board. There were other departures 1. Loose fitting of a clamp to a water pipe for bonding. 2. No bond at the gas meter. 3. A 32A MCB for a radial circuit to a single, twin socket outlet.


    Jaymack
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    Jaymack:

    Sorry, I should have have said that there are 8 circuits involved here, not just a lighting circuit for downstairs and another for upstairs, ditto for the 13A sockets. The only reason I can think of behind the irrational mix, was that the cables were simply too short and should have been lengthened; this is a basic departure from the regulations.


    I am surprised and saddened, that there some who think that it is OK to have this arrangement on a dual RCD board. There were other departures 1. Loose fitting of a clamp to a water pipe for bonding. 2. No bond at the gas meter. 3. A 32A MCB for a radial circuit to a single, twin socket outlet.




    I think that I would prefer to use the nearest two MCBs rather than splice in a six inch length of cable amongst the snakes' wedding.


    As it stands, the 32 A MCB is satisfactory even with 2.5 mm2 cable assuming RM C (including 57 and 58) because even if the socket is overloaded with 2 x 13 A, the cable will not be. After all, what's the difference between that and an unfused spur (Fig 15B)? The danger is, of course, that the circuit might be extended; but the circuit is what it is and not what it might be.

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    My personal view is to have the ground floor lighting and upstairs sockets on one RCD and the upstairs lighting and ground floor sockets on the other, but that is the way I like to do it as I am old school.


    There is no specific Regulation that requires this Also the designer of the installation, and we know all installations have to be designed by one of more skilled persons, would have considered the Fundamental Principles of BS 7671 and the CDM Regulations when designing the installation. I competent designer would have considered the requirements of 314.1 when carrying out his/her design no doubt. 


    I generally would not record it on an EICR as a non-compliance but would probably mention it in the Summary Section E box.
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    I generally would not record it on an EICR as a non-compliance but would probably mention it in the Summary Section E box.



    Section E , in model forms, is for a summary that would include things that could impact on safety. So if something is of concern, it should have attracted a place in the Observations first. Personal preference should be expressed elsewhere, say, as an informative.
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    The only reason I can think of behind the irrational mix, was that the cables were simply too short and should have been lengthened; this is a basic departure from the regulations.




    Please check which regulations it fails to meet. I claim it is perfectly possible for what you have described so far to be compliant with BS 7671. As it is also  quite possible the spur on the B32 with a zero length ring final. though that will depend on grouping factors and if it is routed through insulation.

    It may not be pretty, and I think we'd both be happier to see it on a 20 or even a 25A breaker, but it is quite possible that no regulation is broken - or perhaps there are other factors you have not described that do make it immediately non-compliant..


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    Chris Pearson:




    As it stands, the 32 A MCB is satisfactory.




     




     

    What is now the current rating for a twin 13A socket outlet?.


    Jaymack
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    Chris Pearson:




    I think that I would prefer to use the nearest two MCBs rather than splice in a six inch length of cable amongst the snakes' wedding.





    Au contraire the noo - See 314.1 (i).


    Jaymack

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    314.1

    DIVISION OF INSTALLATION

    Every installation shall be divided into circuits, as necessary, to:

    (i) avoid danger and minimize inconvenience in the event of a fault

    (ii) facilitate safe inspection, testing and maintenance (see also Chapter 46 and Section 537)

    (iii) take account of hazards that may arise from the failure of a single circuit such as a lighting circuit

    (iv) red uce the possibility of unwanted tripping of RCDs due to excessive protective conductor (PE) currents not due to a fault

    (v) mitigate the effects of electromagnetic disturbances (see also Chapter 44)

    (vi) prevent the indirect energizing of a circuit intended to be isolated.




    I think this is the politicians use of the word "minimise" of the inconvenience, meaning 'not make it overly big' rather than the engineering one where we really mean 'make it as small as is possible'

    If not, then circuits can always be subdivided further, until every light and socket would be on an individual RCBO and we do not normally do that.

    The acceptable level is when it is not tripping often enough to be a problem. Has this one tripped recently?

    One might argue that the best thing to reduce inconvenience for most users is to fit the CU at eye level and have an emergency light above it, not any particular configuration of RCDs or RCBOs

    It certainly does not say that  2 RCDs is OK but 3 would be overkill, and 1 would not be quite enough, but consumer unit makers seem to have done that Goldilocks analysis, and decided that is the case  for many of us.


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    davezawadi:

    ..... A quick swap around of a couple of MCB's would fix it anyway. 



    Is there a requirement for MCBs to have reducing ratings working away from the RCD? ie, in reverse order: 40, 32 , 32......16,..6, 6  Or just common practice?

    Clive
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    commonly seen but the bus bar is not tapered, so you could do it either way.

    One of the older Wylex hot wire fuseboards had some beefed up brass works to the first position, and this was the only one supposed to take more than  a 30A fuse - used when showers and larger cookers came in. There may be some collective memory.

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