One cable, two seperate switches...HELP!

[Essennkay]

Hi everyone,

I have been on this forum for a while as a reader but i had to join as i run into a problem while trying to put a new light in my room..

I want to change my bedrooms 1 gang switch to a 2 gang switch, then run a new cable from the switch to a new light (hopefully sharing the live from the existing light at the socket).

BUT... the light switch in my bedroom shares the same cable as the sitting room light switch. Both rooms light switches are directly back to back, so if i open my sitting room light switch, directly behind it there is a hole which feeds a shared live and the neutral to my bedrooms switch.

I am completely baffled because the neutral is only used for my bedroom and is not shared or connected to the sitting room switch..

I have provided pics below. The switch with the ground cables is the sitting room switch then you can see where the shared live and single neutral are pushed through the wall, where it is connected to my bedroom switch!

Untitled

• Essennkay
• 1 Aug 2014
• 1

Untitled

• Essennkay
• 1 Aug 2014
• 1

Untitled

• Essennkay
• 1 Aug 2014
• 1

 

[Grenage]

There's no neutral in a switch; surely the live is coming into one, and from there also being delivered to the second switch. Both switches have a switched live going to their respective lamp fixtures?

One live in, two switched-lives out.

That's what it looks like to me, but I'm no sparky. It also looks like the first switch fascia isn't earthed.

 

[ban-all-sheds]

There are no neutrals at either of those switches.

If there were then you'd get a &*$&"^%$#@ great flashbang when you turned them on, breaker tripping/fuse blowing and switch destruction.

You will not be able to add another light simply by cabling it to the new switch.

Please learn how lighting circuits work before trying to fiddle with them - doing electrical work when you don't understand what's going on is a Bad Idea.


//www.diynot.com/wiki/electrics:lighting


There is also no earth at the bedroom switch - you MUST provide one - it is dangerous without.


In your position I would be immediately very suspicious about the rest of my installation - it has clearly been ministered to in the past by the sort of idiot who would use a surface mount pattress when he should have used a metal box, and far more seriously would install a metal switch and not earth it. That can kill.

I strongly advise you get an electrician to inspect and test the whole thing - who knows what other delightful things the idiot has bequeathed you.

 

[maltaron]

It is perfectly simple. You are assuming wrongly that blue is neutral, when in fact you have a 3 core cable - red = line in; yellow = first switched live; blue is second switched live. To make it safe the earth should extend thro' the wall to second switch. To add a light with a two gang switch, swap the existing wires as is to one switch, extend the red to the second switch common and add your new switch cable to line 1 on the second switch. The neutral and earth you will have to find in the ceiling off another light.

 

[EFLImpudence]

To add a light with a two gang switch, swap the existing wires as is to one switch, extend the red to the second switch common and add your new switch cable to line 1 on the second switch. The neutral and earth you will have to find in the ceiling off another light.

Surely, it would be better to do it the 'normal' way.

If he can't supply the new light with N and L from the circuit in the ceiling then he won't be able to do it.

 

[maltaron]

The OP has indicated that he would run another switch wire for the other light.

 

[Essennkay]

Thank you for all your comments, its been really really helpful.

It is perfectly simple. You are assuming wrongly that blue is neutral, when in fact you have a 3 core cable - red = line in; yellow = first switched live; blue is second switched live. To make it safe the earth should extend thro' the wall to second switch. To add a light with a two gang switch, swap the existing wires as is to one switch, extend the red to the second switch common and add your new switch cable to line 1 on the second switch. The neutral and earth you will have to find in the ceiling off another light.

Ahh i see, so what i have at the moment at the switches are 'switch legs'?

So i got to:

1, Tap into the earth and push it through to my bedrooms switch (and ground the switch cover).
2, transfer the old switch wiring to the new 2 gang switch, then extend the red to the second switch common, and then run the new cable from the new lights live to line 1 on the second switch.
3, run another cable from the new lights neutral and ground to the existing light in my room, then tap into it with a chocbox and terminal strip.

Does that sound about right?

One more thing (sorry for all the questions!), the downlights im using stated in the instructions they dont need to be grounded.. So shall i just run a neutral from the new lights to the old lights?


@EFLImpudence whats the normal way? Am i making more work for myself the way im doing it? Im all ears!

 

[EFLImpudence]

Well, as you have to run a cable from existing light to new light for a Neutral and Earth, you may just as well run the Line (live) as well.
Then the switch cable can be used for Line and Switched Live.

//www.diynot.com/wiki/Electrics:Lighting-Circuit-layouts

No need for additional chock box - join to existing terminals.

 

[Essennkay]

Well, as you have to run a cable from existing light to new light for a Neutral and Earth, you may just as well run the Line (live) as well.
Then the switch cable can be used for Line and Switched Live.

//www.diynot.com/wiki/Electrics:Lighting-Circuit-layouts

No need for additional chock box - join to existing terminals.

Ohh i get ya, so if i didn't want the switch in the same place as the other switch i could have done it that way. If i didn't already run the new cable from the existing switch up the wall, through the ceiling and plastered over it i would have contemplated doing it that way tbh.

 

[ban-all-sheds]

the downlights im using stated in the instructions they dont need to be grounded.. So shall i just run a neutral from the new lights to the old lights?

Even though you don't connect it to the light you must take an earth to it, and make it safe in a piece of choc-block. The cable you use will have an earth core anyway.

And EFLI is right - just extend the lighting circuit to the new light, and take a switch cable from there. There's an article in the Wiki about how to add a light which doesn't have a terminal to take a permanent live.

 

[ban-all-sheds]

If i didn't already run the new cable from the existing switch up the wall, through the ceiling and plastered over it i would have contemplated doing it that way tbh.

Well there's your switch cable - you're all set to do it the normal way.