Mystery wire in 2 way ceiling rose

[livingdaylights]

Can any one help, I have a mysterious wire in my ceiling!

The wife wasn't happy with the standard light fitting in the lounge so went out and bought a new one. After some extensive nagging I finally attempted the swap over today.

Disconnected old light fitting and ceiling rose (as new one was supplied with chocblock type terminals). OK. I admit it. I never bothered to study the wiring configuration and now I am confused as to how it all wires up. It's a two way switched circuit by the way.

I have studied your excellent guides on lighting circuits etc. in the sticky section and I understand the configuration of two way circuits with the switched live wire etc.

Coming out of the ceiling I have three cables. Two of these are two core plus earth. However the third cable consists of just one core which is black. I cannot for the life of me understand how this can be. Surely (if this is the switch cable) it needs a minimum of at least two cores.

I am mystified. The strange thing is that prior to me disconnecting the old light fitting, it worked perfectly via the two switches.

Can any one help........

 

[viewer]

Sounds like live to lamp from switch. Check with multimeter. One switch will have connection to power supply, the other will have a connection to the lamp. The two switches are connected by a pair of wires (strappers).

 

[livingdaylights]

Thanks for your help Viewer,

Is this the switched live then?

I don't fully understand. Could you point me to a diagram?

 

[viewer]

Sw1 Sw2

_________________________
__Supply_______/ _____________Lamp
________________________/


Hello livingdaylights, I hope this shows OK. It does sound like the switched live and, if so, should have a red tape on it. Between the two switches is probably T+E with the black sleeved red at the ends. Lamp will have neutral into rose. Supply into Sw1 may be a jumper if 2gang+. As you can see above light is off, but either switch will turn it on and then either switch off again. I can't guarantee this is how yours works, but you'll be able to power off then check for jumper inside a switch (probably furthest from lamp) and lamp to switch with multimeter or battery and bulb.
Good Luck

 

[viewer]

OOps drawing didn't come out! I'll try again.
Hold on

 

[viewer]

Hi Living daylights, Can't draw! Never mind the site below has a good line drawing on page one. Have fun.

http://www.tlc-direct.co.uk/Technical/DataSheets/MK/WiringDiagrams.pdf

 

[livingdaylights]

Thanks for your help and the diagram.

So would I be right in saying that the neutral to the lamp is effectively taken from the feed in/feed out T+E's via the rose. The switched live comes from the T+E from the switch (of which only one core is used)?

 

[viewer]

Yes, that's right. May, or may not be T+E from switch to lamp; if it is then only one wire will be to switch.
Hope it's working now.