Light switch wiring - please help

[maxadsie]

I have 3 x 3core cables into a light switch, which I assume are from CU and 2 to lights. I also have a 10th cable, red sheathed in grey. What is this and what should I do with it? How can I tell which is the live feed and is this important?[/b]

 

[peterduckett]

Sounds like you have a loop in circuit but in you wall socket i'm guessing the single core is a switch cable exactly how many lights and switches are their controlling this part of the circuit?

 

[1john]

have you removed the switch already? can you take a photo?

 

[ericmark]

There is no standard on how lights should be wired however there is a convention which most electricians follow.
This is to use the ceiling rose at each lamp as a junction box and as a result no neutral cables are taken to the light switch.
Also any two way or intermediate switching is done switch to switch and does not involve the main lamp.
We therefore have two core and earth cables (so really 3 cores) between lamp and switch and three core and earth (so really 4 cores) between switches all core except for earth being line.
(Note:- Both Neutral and Line are considered as Live however non electricians often consider only the Phase or Line wire as being Live)
Since two core and earth (or twin and earth as it is normally called) is really available and triple and earth is not quite so common many people use other methods of getting that extra wire.
I will guess that what you are calling three core is really twin and earth and the extra wire is because of some two way switching.
So exactly what cable is it?
How many switches on the plate?
Is there any two way or intermediate (latter used when more than two switches used) in use?
What type of lights. i.e. do they use standard ceiling rose? In some cases where spot lights have been fitted as original lights the switch box is used as junction box.
There are many wiring diagrams on this web site I include my little one showing general method. Before anyone can really help we must work out what you have.

Standard Lighting

• ericmark
• 17 Aug 2008
• 13

Standard lighting diagram

 

[maxadsie]

Of the 3 twin and earths, 2 are live (red core). I thought these may be a ring circuit so, I joined them and then connected to both commons on the switches. Then put the single red on to the L1 on one switch and the red from the 3rd twin and earth on the other side L1. Neutrals and earths together. This then left me with the light in the lounge permanently on. The hall light didn't come on! This might have been a blown bulb. Might. However at the ceiling rose someone has wired 2 red cables together and then to one side of the light, and 2 black (neutrals) together and then to the other side of the lamp. I left it at this point. Someone has said that there may have been another cable in the ceiling which would be the neutral. I am lost!