Adding unpowered lighting extension to existing switch

[Bob2323]

Hi all,

I have just replaced a faulty two gang switch in my kitchen with a 3 gang, two way but wired for one way. The incoming cable is 3 + E and proves single switching to two sets of lights.

I want to use the remaining switch for a new light in the larder. Can I power this light from the switch, and if so, how ? Or do I have to provide power separately in some way ?

Comments please ?

Bob.

 

[PBC_1966]

If there's just a single 3-conductor (plus earth) cable there at the moment for two switches controlling two different lights, then one wire will be the power coming in to both switches and the other two will be the individual switched feeds to the two lights. If you were thinking of just running a cable from the switch position to the new light, that won't work as you don't have a neutral to pick up at the switch box.

 

[Bob2323]

Thanks for the reply.

To achieve the objective of switching the larder light through the 3 gang switch, is there any problem with proceeding as follows ?

Take power from the ring main present in the larder, either via a fused box or simply plugging in to the existing socket. Then run a cable to the switch, passing the brown live wire through the switch block and bypassing with the blue neutral wire, and continue to the light. Attaching the earth wire to the metal switch.

Thanks.

 

[bernardgreen]

The only snag with that is that you have circuits from two MCBs ( the lighting MCB and the sockets MCB ) in the same switch plate. At some time you or someone else may want to work on the switches and they must for their safety turn off BOTH MCBs. As time passes the memory of two circuits in the switch may be lost.

 

[ban-all-sheds]

Document it then.

 

[PBC_1966]

either via a fused box or simply plugging in to the existing socket.

The former would be preferable. Running fixed wiring in this sort of situation and then just plugging in to a socket is kind of messy.

The only snag with that is that you have circuits from two MCBs ( the lighting MCB and the sockets MCB ) in the same switch plate.

That happens all the time with things like a 2-gang switch for hallway and landing lights where they're on different circuits.