LANDING CEILING LIGHT WIRING

[Robdiycm9]

Hi, in the process of fitting a new light for the landing, and have a problem. On removal of old light, live and neutral were easily identified, but have a third single core black sheathed wire that was connected to what appears to be an isolated connection on the fitting.
At first I thought it might be the earth, but two things puzzle me....1. Shouldnt it be copper? instead of a silver metal and 2. On testing it, its also live!
What should I do with this third mystery wire?....whats its purpose?...
Thank you[/img]

 

[rjm2k]

More detail needed and photos would help. If its a landing I guess there's 2 way switching? What else is there? How did you test this wire, bear in mind that if you say neon screwdriver you risk the wrath of the neon screwdriver police,

 

[EFLImpudence]

It'll be older tinned copper wiring.

Can't tell from here what the spare wire is so just terminate it in a connector block and position safely.

 

[PrenticeBoyofDerry]

Landing light! You would expect a two way function, so the isolated connection, is likely to be part of the that.
A picture or if you could identify the terminal points on the switch plate, would be handy!

 

[Robdiycm9]

Thanks for replies. I tested wires with one of those pointer devices that bleeps and lights up when it detects a live wire. I did attempt to post two pics of the wiring with original posting, but it seems like something went wrong. Think theyre on my profile as an album....
Anyway, gonna try that suggestion to isolate this mystery wire, specially as it was originally screwed into the landing light and wasnt physically connected in any way at all to other wires.
Will also attempt to fix this issue of my missing pics...Many thanks and will post update asap.

 

[Johnmelad]

Untitled

• Robdiycm9
• 26 Nov 2012
• 1

Untitled

• Robdiycm9
• 26 Nov 2012
• 1

 

[ricicle]

Safety first ! I hope your new light doesn't require an earth as you do not appear to have one in your lighting circuit. You must not fit the light if this is the case as you will be creating possible danger to yourself and others.

Secondly, are you sure the single black wire wasn't the switch wire as the system looks like a candidate for two-way switching using singles. This would make the red and black permanent line and neutral and the single black the switch line ?
Also watch out for the circuit line being fed from the downstairs circuit !

 

[rjm2k]

What's in the switch(es)? can you post a photo of that/those too?

 

[PrenticeBoyofDerry]

How did you test for neutral?
And the voltage stick you are using will not give us the value of the reading, so the results could be a little ambiguous.
But looking at your fitting and cables, it would suggest that the red is live and the black paired with the red is the neutral. You may find a a bare copper wire within the sheath of this cable that could be used as CPC/Earth but would only be a valid earth connection if continuity is back to the board.
As for mystery cable a little more investigation is needed.