Hidden in a recent thread which many people probably gave up reading was the suggestion/implication that it may be acceptable for a cable not to be provided with overload protection if it is part of dedicated wiring for a single load, provided that adequation fault protection was in place. The example in question (from overseas) was a length 0.5mm² felxible cable in a circuit protected by a 16A OPD.
I realise that this may often be technically compliant, by invocation of 433.1.1(ii), but do people regard it as either sensible or good practice? Personally, I have my doubts.
To cite the example I mentioned in that other thread, what would people think (indeed, how would they deal with this in a PIR) if they found a dedicated circuit, say to an immersion heater, wired completely or partially (maybe just the final flex) in 1.5mm² cable, but protected with (for whatever reason!) a 32A or 40A MCB? Would you regard this as OK so long as the circuit's fault protection checked out satisfactorily?
I realise that 433.1.1(ii) only applies when 'overload' in the normal sense is not considered to be a likely possibility, but my main concern would probably be in relation to faults in the load which resulted in less-than-zero-impedance L-N faults (rather than the 'bolted short' fault considered by the regs) - against which the cable might have inadequate protection with the arrangement I have described.
Kind Regards, John
I realise that this may often be technically compliant, by invocation of 433.1.1(ii), but do people regard it as either sensible or good practice? Personally, I have my doubts.
To cite the example I mentioned in that other thread, what would people think (indeed, how would they deal with this in a PIR) if they found a dedicated circuit, say to an immersion heater, wired completely or partially (maybe just the final flex) in 1.5mm² cable, but protected with (for whatever reason!) a 32A or 40A MCB? Would you regard this as OK so long as the circuit's fault protection checked out satisfactorily?
I realise that 433.1.1(ii) only applies when 'overload' in the normal sense is not considered to be a likely possibility, but my main concern would probably be in relation to faults in the load which resulted in less-than-zero-impedance L-N faults (rather than the 'bolted short' fault considered by the regs) - against which the cable might have inadequate protection with the arrangement I have described.
Kind Regards, John