Extra wire in ceiling light

[Larry Stoter]

Just preparing a room at home to redecorate. Removed the ceiling light fitting and there's an extra cable …

As expected, there are 2 x loop cables and a switch cable. Then a single, double insulated wire. Black inner insulation and it was connected to the rest of the black/neutral wires. Not connected to any other wires, it's carrying 240 V with respect to earth.

Disconnected from light and light works OK. Haven't yet found anything else not working.

Any ideas what it might be?

 

[Taylortwocities]

Untitled

• Taylortwocities
• 17 Apr 2008
• 30

Maybe follow the cable and see where it is from. May be an over-ride switch.

 

[Larry Stoter]

Untitled

• Taylortwocities
• 17 Apr 2008
• 30

Maybe follow the cable and see where it is from. May be an over-ride switch.

Disappears into the ceiling cavity …

 

[davelx]

How old is the house/wiring?
Is this an upstairs room?
Do you have two-way switching for the landing light? Does it still work?

 

[sparkwright]

At a guess some kind of borrowed neutral, for a later addition somewhere, and the live has been borrowed from another point.

'Borrowed' implies it's not right, but it could be perfectly correct.

Hard to say without being there and dismantling the place.

 

[davelx]

Indeed - and the answers to my questions in the preceding post might well help to identify if that were the case!

 

[Larry Stoter]

How old is the house/wiring?
Is this an upstairs room?
Do you have two-way switching for the landing light? Does it still work?

House is 1980s

This is a downstairs room.

Yes, there is 2-way switching for the landing light and yes, it still works with this extra wire disconnected.

I could understand if there were both extra "live" and "neutral" wires to supply another light no longer in operation but it's a single wire. Why would anybody run separate wires to different points to power an additional light …?

 

[EFLImpudence]

Might have been to take a neutral to a switch.

 

[Larry Stoter]

Might have been to take a neutral to a switch.

It's carrying 240 V relative to earth …

 

[EFLImpudence]

Ok. Not that then -

now.

 

[Johnmdc]

Could it be feeding an outside light, with the live coming from a switch. That is what was done in my house when it was built.