2 gang bridging power

[deuce22]

Hi.

Can someone please tell me how to get power to a second light using a 2 gang switch.

Theres the main cable coming from the consumer into the ceiling rose (out in my porch) and then to a switch wire going to a 2 gang switch.

I would like to add another light and connect it into the other gang on the switch.

A friend have said I can get power for the second light by bridging between the two gangs.

Is this possible or do I have to run a loop from the first ceiling rose and then to the switch.

Cheers.

 

[ricicle]

If you are taking the cable from the switch to the light then a neutral is required at the switch. If you are taking the cable to the new light from the existing then an extra switch wire is needed to the switch position, so either way 3 core and earth cable is required from the exsting light to the switch.
In both cases the commons (feed lines) will be linked across in the switch.

 

[echoes]

A few ways to do this, but if you have no neutral at the switch, then loop in the new ceiling rose from the existing one, and then run a switch drop from there, like you said.

If you have a neutral at the switch, then just run switched line and neutral from the switch to the new rose. The unswitched line for the second switch can be taken from the unswitched line on the first switch using a short length of wire, as your friend said.

[EDIT] oh, and as ricicle said, faster than me.

 

[deuce22]

Hi.

I don't really want to loop from the ceiling rose to the new light as there is a lot of work involved removing things for me to get at it.

I have used twin and earth for the cable, so I'm assuming that unless I run 3 core and earth from the ceiling rose to the switch I cannot go any further.

It is possible that I can pull new 3 core and earth through, so can you explain where each cable goes.

Thanks.

 

[plugwash]

Think about it, at the light you have permanent live, switched live for the existing light, netral and earth. At your switch right now you have permanent live, switched live for the existing light and earth but you don't have neutral. By replacing the cable with three core and earth you can bring the neutral down to the switch.

If you can't figure out how to wire up a light switch given a permenent live, a neutral and an earth then you really shouldn't be donig electrics until you have done some basic reading up on what a switch does.

 

[deuce22]

Thanks plugwash.

I have not done this before, so if you could tell me which cables go where then that would be appreciated.

I have got basic knowledge, but I have never come across this.

Thanks.

 

[RossR]

If the existing switch drop is only two core and earth, then you can't do it without putting new cable to the switch. You're unlikely to be able to pull new cable in without damaging decoration, unless it is run in conduit and you have access to the top.

 

[deuce22]

Hi RossR.

I have managed to get the 3 core + earth from the ceiling rose to the switch.

I just need to know exactly what cables go where.

Thanks.

 

[RossR]

OK. Let me check I understand the situation.

You have an existing light with ceiling rose. (Rose 1)
You have a new light with ceiling rose (Rose 2)
A 2 Core + Earth cable goes from consumer unit to Rose 1.
A 3 Core + Earth cable goes from Rose 1 to the 2 gang switch.

If that's all correct you'll also need a 2 Core + Earth from Rose 1 to Rose 2.

Have I got anything wrong?

 

[RossR]

You want something a bit like this but with the incoming L looped through the first rose, and all earths connected together:

(ignore the colours on this picture, it was the best I could find)

Inside the switch you connect the incoming L to both "Common"s. This is what your friend meant about bridging. You then connect the other two cores to an L1 each.

The wire marked S2 in the picture will have to be joined in the first rose somehow. I'd recommend an insulated crimp, but only if you have a ratchet crimping tool. N and N2 also need to be joined in the first rose, but this can be done using the terminals in the rose.

 

[RossR]

You should also mark all lines and switched lines with a brown sleeve, at the ends, unless they are already brown (or red).

All earth conductors should be sleeved with Green/Yellow.

I'm sure I missed some other points. For example you should really do a whole load of tests, but I doubt you've got a suitable tester for them.

 

[deuce22]

Hi RossR.

I have 2 core and earth connected to the 1st ceiling rose and as there were no more lights there was a 2 core and earth as the switch wire.

I have managed to replace the switch wire with 3 core and earth.

I want to add another light, but it will take a bit of work for me to run another cable from the 1st rose to the 2nd light.

I was told that I can use the 2 Gang switch to get power to the 2nd light without having to connect the ceiling rose/lights together.

Thanks.

 

[yorkspark]

In order to use the switch to feed another light fitting you will also need another twin and earth taking to the switch from the pendent then connect up as follows :-

brown of 3 core to live in on pendent
black of 3 core to switch live on pendent with brown sleeving fitted
grey of 3 core to neutral in with blue sleeve fitted

brown of twin and earth to switch live of new fitting
blue of twin and earth to neutral of new fitting

link both commons together in switch with brown of 3 core
connect black of 3 core to L1 in switch with brown sleeve
connect grey of 3 core with blue sleeve to blue of twin and earth using connector
connect brown of twin and earth to L1 on 2nd switch

connect earths together and sleeve green/yellow and bobs your uncle

 

[deuce22]

Hi yorkspark.

Can I just confirm.

I have a 2 gang switch and I want each light to be linked to a separate switch so they work independently from each other.

I only have power going to one pendant and then a 3 core and earth coming from that pendant to the switch.

Is what you've explained going to let me do this or is it that the both lights will operate from only one switch.

If I can do what I want to do, can you confirm that another twin and earth cable is needed from the 1st pendant alongside the 3 core and earth.

Thanks

 

[RossR]

Well you need a cable of some sort going to the second light. Otherwise it'd be wireless power transmission!

Two possibilities are:

1) A 2 Core + Earth between the two lights (in addition to the 3C+E you have between the switch and old light)

2) A 2 Core + Earth from the switch to the new light (in addition to the 3C+E you have between the switch and old light)

Only you know which is easier to route. I've assumed the first; yorkspark has assumed the second.

p.s. You can use 3C+E as 2C+E if it's all you've got. I'd earth the spare conductor and sleeve it in green/yellow.