Discuss lighting circuit mess,borrowed neutral? in the UK Electrical Forum area at ElectriciansForums.net

saint elmo

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im figuring out my upstairs lighting circuitsto tidy it up and get rid of the old JB's the upstairs lighting circuit is a mish mash of 1.5 and 2.5mm2 cable mostly 2.5mm2 which is annoying as 2.5 wont fit into the down light push fits i have.
but the white wire is confusing me a bit


1st pic red and white wires going into landing light (connected to downstairs circuit)

2nd pic red wire going down

3rd and 4th pic white wire going into the junction box for the upstairs lighting circuit

dont want to open up the octopus just yet to see what it is connected too before i know how im putting everything back together

is this what is called a borrowed neutral?
 

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As above, the wiring appears to be installed to an extremely poor standard. It is likely that substantial work will be required to correct the problems. As such, I'd also recommend calling in an electrician.
 
From pictures I can't tell if borrowed neutral, I know there was a problem with this house, and it turned out to be at the 4 gang switch in the hall, but it could have been that way since the house was built, as until I fitted all RCBO it would have needed a very good EICR to have highlighted the fault.

In the main reason we realise there is a borrowed neutral is the RCBO or RCD trips when we turn on the lights. And in real terms mainly caused by a borrowed line.
 
That is really rough, and if the red wire really is in use then it is exposed primary insulation and a big non-no for electrical installations! Also white wire is uncommon for power systems, it was used as a 3-phase colour way back so it either points to some ancient stuff being re-used or someone using whatever cable they had to hand/cheap to finish something.

Sometimes you get to a point when the best solution is a professional rewire and deal with all of the issues in one go. This looks like one of them!
 
USA use white, and with British white was unfused ignition supply, fused was green, non ignition unfused brown and fused purple. So it is possible that is auto electric cable.

As to if you can sort, we have no idea of your skills.

You ask what is a borrowed neutral, well every circuit is fused, that's what defines the circuit, some current limiting device, so if all the lights are from one current limiting device then you can mix and match as much as you want with the lighting circuit, it may be bad but not a borrowed neutral, the borrowed neutral is where the neutral for one circuit is used by another, so you can have a wire which seems dead, but which some thing switched on it becomes live.
 
As above. Id be wanting to start from scratch with that lot and work out what was linked to what. If there is a borrowed neutral my first port of call would be on any two way lighting between upstairs and downstairs. Post 2 is your answer.
 
Replacing the lot in 1mm T&E (or 3&E for two-way switching) and some modern Wago style junction boxes is not much in material costs. Time, skill and test equipment of course have a price associated with them, but if most of those cables are loos in the walls down to switches, etc, you can use them to pull in new runs of cable ready for a neat and sound connection up top (or under floor as appropriate) so it need not be a very time consuming job.

But when considering a rewire style of work think carefully about what you have and where it is placed as now would be the time to fix any stupid layouts of the original design!
 
Replacing the lot in 1mm T&E (or 3&E for two-way switching) and some modern Wago style junction boxes is not much in material costs. Time, skill and test equipment of course have a price associated with them, but if most of those cables are loos in the walls down to switches, etc, you can use them to pull in new runs of cable ready for a neat and sound connection up top (or under floor as appropriate) so it need not be a very time consuming job.

But when considering a rewire style of work think carefully about what you have and where it is placed as now would be the time to fix any stupid layouts of the original design!
i worked out where everything is going and got new wago boxes yesterday, it should be straight forward
ill find out which switch the red wire is going to see what is going on with that and run a proper cable instead
the red +white wire goes to the landing light (downstairs circuit)
the red wire goes down and the white wire taps into the upstairs circuit so definatley dodgy
 

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