Borrowed Neutral

[ml1936]

When Installing RCD or RCBOs for lighting circuits, and it becomes apparent that there is a borrowed neutral between up and down circuits, and the homeowner wont pay for rectifing this or re-decoration. Would it be ok to put both circuits into the one MCB or RCBO? I know its not ideal but if your hands are tied, its a safer solution isnt it?

 

[Cremeegg]

If they absolutely refuse to pay then yes I've done it - as you say whilst not perfect its safer than it was before. I make sure I label the CU and make a note on the EIC and in a covering letter that goes with the receipt and EIC when the cheque has cleared.

 

[SparkyFromTheValley]

personally, if in same situaion and rewire not an option, and provided it is JUST lighting circuits which share the neutral then it should be ok to share an MCB. no need to use RCBO on a lighting circuit (although it could be covered as part of wider RCD protection), provided there is suitable fittings in the bathroom (i.e. sealed lights and low voltage fan/shaving point).

important: the MCB shouldn't allow a current through larger than which the cable can take. So for standard 1.5 t+e cable a 16A MCB is a maximum. if this trips due to overload a rewire will be needed.

 

[mikeyd]

no need to use RCBO on a lighting circuit (although it could be covered as part of wider RCD protection), provided there is suitable fittings in the bathroom (i.e. sealed lights and low voltage fan/shaving point).

I'm no electrician but I don't think this is quite correct.

important: the MCB shouldn't allow a current through larger than which the cable can take. So for standard 1.5 t+e cable a 16A MCB is a maximum. if this trips due to overload a rewire will be needed.

You can NOT put a 16A MCB on a normal lighting circuit. For a start the switches would normally only be rated for 10A

 

[ban-all-sheds]

Would it be ok to put both circuits into the one MCB or RCBO? I know its not ideal but if your hands are tied, its a safer solution isnt it?

Would that, to the best of your knowledge and belief, comply with BS 7671:2008?

 

[Adam_151]

Probably not to the letter, but sometimes you have to make the best of a bit of a rubbish situation and note it under comments on existing on the EIC

 

[ban-all-sheds]

Probably not to the letter, but sometimes you have to make the best of a bit of a rubbish situation and note it under comments on existing on the EIC

But it's not just existing - you have changed it to to put all the lighting on one RCD.

120.3, final sentence?

 

[securespark]

in a covering letter that goes with the receipt and EIC when the cheque has cleared.

You hold back the EIC until payment is received?