Light Switch only has one wire


Postby Sean Merry » Mon Jan 21, 2008 12:00 pm

As per other contributors I have tried to replace a light (in the hall) and have not made a note of the wiring pattern (lesson learned).

Now I am faced with two cables from other lights (red, earth and black) and a single switch cable, which is black but it is live. The switch which controls the hall light is a double switch. From above I can see that from this switch there are three cables, one normal cable to the light in the front room, another single to the dining room light (which the switch also operates) and the other single to the hall.

I have completed the circuit ignoring the hall light switch and all other lights work ok.

All I need to do now is figure out how to incorporate a switch with only one cable!

Any help would be appreciated.

Thanks
Sean Merry
Posts: 2
Joined: Mon Jan 21, 2008 11:27 am

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Postby ericmark » Mon Jan 21, 2008 3:13 pm

The projects section with pictures I am sure will help. I have read and re-read your post and I am guessing that when you say only one cable you mean to the switch. I wonder if it is three core? That would not be normal but I suppose a single feed could be taken to switch for two lights? It is confusing as to what you have? Normal (except for last light with no feed out) each rose has three cables and each cable has two cores and earth. Of these one feeds in, one feeds to next lamp, and one goes to switch. Where two switches are on same plate two complete cables would normally go to switch one from each lamp. If the original build did not use ceiling roses for example where spot lights are used junction boxes do the same job. But there are no rules written in stone as to how they are wired and an electrician could use a different method to get same result. I have seen power taken to switches with spot lights to save on junction boxes for example. To direct you with out more info would be wrong. If just a case of working out which wires are which when using standard wiring I can help. In fact you will find it on other posts so I wait to see exactly what the problem is.
ericmark


Postby kbrownie » Mon Jan 21, 2008 6:14 pm

HI Sean Merry,
A little confused, you say that the switch in the hall is a double switch but works Front Room, Dining Room and Hall? and what's a normal cable? I guess you mean twin and earth (red, black and earth) with pvc grey sheath. Without knowing the proper configuration of cables to lights and switches it would all be guess work.
So i'm guessing! so forgive me if i'm wrong, so taking into consideration you say the black switch cable is live at the ceiling.
This is what i'd do:
2 reds terminated together on there own.
2 blacks (not single switch wire) terminated at neutral side of light (blue in flex)
Single black (should be sleeved brown) terminate live side of light (brown in flex)

If that don't make sense either post a more detailed desciption of cable configuration or get an electrician in.

Remember to safely isolate before working on electrics and if in doubt get the sparky out.
Best of Luck
KB
kbrownie
Posts: 1756
Joined: Mon Mar 05, 2007 9:36 pm


Postby Sean Merry » Wed Jan 23, 2008 2:19 pm

Result :D :D :D

Thank you both for taking the time to reply, special thanks to kbrownie whose wiring suggestion was spot on.

If I get stuck again (highly likely) I will know where to come.

Regards

Sean
Sean Merry
Posts: 2
Joined: Mon Jan 21, 2008 11:27 am


Postby kbrownie » Wed Jan 23, 2008 5:50 pm

Hi Sean
really happy to hear your lights are now function correctly and thanks for the praise, some really good knowledge on this site.
Don't forget us next time your in the dark.
KB
kbrownie
Posts: 1756
Joined: Mon Mar 05, 2007 9:36 pm


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