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Definition of 'electrical installation' and requirement to upgrade existing to current regs?

MFr

Hi there

Have found an old damaged 30A JB on a ring final under the floorboards, which I was going to replace - although it spurs to a 2G socket, from which three further sockets are spurred. Obvs you can't have a spur off a spur without a fused connection (which this doesn't have), but is there a specific requirement to upgrade the existing wiring either (a) once the 'non compliant' aspect has been found or (b) as a result of the intervention in the circuit (i.e. does the replacement of the broken JB automatically mean that the spur+spur issue has to be rectified also?).

The wiring is not that old (blue neutral plus other evidence suggests probs 15 - 20-ish years max) so not sure if it would have even been compliant with the regs at the time - but would be pretty difficult to either bring the spurs back to the ring or fit a fused connection due to the location / buried cables etc etc. Might be possible to split the ring into two radials etc (which would probably have incidental benefits) but obvs this is an order of magnitude more substantive work-wise than replacing the damaged JB... 

Cheers

  • +1

    Let's forget about 'the Regs' for a moment.

    If a junction box is damaged, that obviously has to take priority and it's a repair.

    With respect to the spur arrangement, it could potentially be quite serious. It seems there is no overload protection (and possibly inadequate overload current protection if a fuse is used) for the 'spur' arrangement - so, potential fire risk. An insurer might not like the fact that nothing was done about it, if there's a fire, and part of the inspection reveals repaired junction box, meaning a missed opportunity to fix the spur too.

    Perhaps note also that a 'direct replacement' junction box under the floor might not be recommended based on current "Wiring Regs" ... a maintenance-free junction box would be needed.

  • +1

    If the maximum expected load is modest, what about fitting a 20 amp fuse or MCB at the origin of the circuit.

  • 0 in reply to gkenyon

    Thanks for the reply - very useful. 

  • 0 in reply to broadgage

    Thanks for the reply... do you mean putting 20A on the existing RFC? I understand that you can have unfused spurs from spurs on 2.5mm radial, but is this also true for an RFC? 

    Load wise, the existing ring (with the spurred spurs) serves a dishwasher and extractor fan (both on switched fused spurs), a fridge (on the RFC), then all of the other non-kitchen sockets in the house (bedrooms x 2, lounge, conservatory - some of which are the unfused 'spurs from spurs')... the other big load devices (hob, oven, washing machine) are on separate rings or radials... so would need to do some sums.

    Thanks

  • +1

    Yes I was suggesting fitting a 20 amp  OCPD to the existing ring final. Not aware of any regulation specifically permits or prohibits  this practice, but common sense and engineering judgement says it is fine.

  • 0
    broadgage said:
    Yes I was suggesting fitting a 20 amp  OCPD to the existing ring final. Not aware of any regulation specifically permits or prohibits  this practice, but common sense and engineering judgement says it is fine.

    Agreed but see comment by the eminent Mr Paul Cook (last sentence in italics on this page);

  • 0

    It is in my view acceptable to down rate the ocpd for a ring final to 20 amps, provided that the maximum sustained demand is reasonably expected to be 20 amps or less.

  • 0 in reply to MFr
    MFr said:
    Load wise, the existing ring (with the spurred spurs) serves a dishwasher and extractor fan (both on switched fused spurs), a fridge (on the RFC), then all of the other non-kitchen sockets in the house (bedrooms x 2, lounge, conservatory - some of which are the unfused 'spurs from spurs')... the other big load devices (hob, oven, washing machine) are on separate rings or radials... so would need to do some sums.

    Sounds like a re-wire may be in order!

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