Spare neutral wire on downstairs lighting circuit.

[David WE Roberts]

I am used to lighting circuits where there is power in, power out, and switch.

3 cables unless there is a spur off the main run to another rose. Just taken down the rose in the dining room as the ceiling is coming out and find an extra single wire - grey sheath red inner - linked into the neutral. No idea what it is for and it disappears into the great wiring void so I can't see where it teminates. I note another single wire running along with other lighting cables - this time with a white outer - and again no obvious termination.

Any ideas what this is for?

Cheers

Dave R

[Toby]

Do you have an RCD on this lighting circuit?

If so, then it will either be connected to something that is also on this same RCD, or not connected to anything, otherwise the RCD would be tripping due to an imbalance between the live and neutral, on this RCD.

Do you have any light switches nearby that would need a neutral, like one with a timer on it maybe?

If you can't trace it to the other end, then I would suggest disconnecting it and then go around checking to see if anything has stopped working. If you have a light at the top and bottom of the stairs controlled by the same switch this would be my primary suspect, as this could be borrowing the neutral from the dining room light.

[David WE Roberts]

Interesting - we do have two way switching on the upstairs landing light and it is on the downstairs lighting circuit. So a single cable could be cheaper to run than Triple&E to get neutral upstairs. There would have to be live fed from somewhere to complete the circuit - possibly the third pair in the ceiling rose. So presumably this is a strategem to avoid buying a short length of three core + E cable?

[John Rumm]

Yup, what he said ;-)

Also, it might be that someone has wired an extra lighting point thus: