Borrowed Neutrel

[BluePhase]

Evening All

Got roped in to looking at the wiring in a friends house over the weekend. They have only been in 2 weeks and in that time, the landing light has never worked. After trying the obvious, removed the ceiling rose cover and found the neutrel had be left out and taped up. Most of you probably know whats coming next.....reconnected and whenever the landing light was switched on, both RCDs (17th board) tripped so as expected, i was looking at the dreaded borrowed neutrel which had been disconnected to stop the rcd tripping.

I am a plant and machinery spark so i have put the problem right in the only way i could think of, running a cable to take a neutrel from the downstairs circuit and disconnecting the borrowed one from the last lighting point. All is now working but is this an acceptable way of sorting this problem?

Also just to satify my own questioning, did both RCDs trip due to the fact that the circuit is 2 way and up and down are both fed from seperate RCDs so the fault was detected across both?

Any advice will be greatfully received, sorry for the long post.

ATB

BP

 

[Electrifying]

........i have put the problem right in the only way i could think of, running a cable to take a neutrel from the downstairs circuit and disconnecting the borrowed one from the last lighting point. All is now working but is this an acceptable way of sorting this problem?

This is the correct way of sorting the problem - just not always feasable due to where to run the cable.

Also just to satify my own questioning, did both RCDs trip due to the fact that the circuit is 2 way and up and down are both fed from seperate RCDs so the fault was detected across both?

That's the reason - not the two-way bit, but you end up with an imbalance on both sides of the board when the light is switched on.

 

[Adam_151]

Just to add that the neutral you run must be insulated *and* sheathed, I might be stating the obvious and if so then apologies, but it wouldn't be the first time I've seen a conduit single run through a ceiling void

 

[OwainDIYer]

The alternative 'fix' is to swap both lighting circuits to be on the same RCD.

Which of course means *all* the lights go out if the RCD trips, which isn't good.

It doesn't actually resolve the borrowed neutral either. But it can get you going temporarily.

 

[BluePhase]

Thanks for your help gents, much appreciated. It has just put my mind at rest knowing that I haven't left something not quite right.

There are no worries were the cable used is concerned, didn't discover the fault until late on Sunday so had no choice other than to throw in a length of 1mm T&E and cut off the live. Bit of a waste of cable i know but it was all i had to hand and needs must.

thanks again for your help

ATB

BP