2gang 2way light switch wiring-Can only get 1 light to work

30 Aug 2014
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United Kingdom
I have bought a new 2 gang 2 way light switch to replace an old MEM delta light switch used to turn the lights on/off for my hallway and my 2 outside porch lamps.
I have successfully wired the com, L1 and L2 in order to get the hallway to work, but I cannot wire the outside lamps correctly and they will not turn on/off.
The problem I am having is that, unlike the hallway wiring, the wiring for the outside lamps does not appear to have a yellow wire, just live (red), neutral (black) and earth (green&yellow).
Please could somebody give me some advice on where to wire the red and black into the com, L1 and L2? And, could it be that I have to add a link wire to connect one side of the switch to the other?

Any help is greatly appreciated!
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Tried red in C and black in L1?

There is only one switch for this light?
Yes, currently have it wired with red in c and black in L1 but nothing. I have one switch plate with two flick switches (hope that makes sense). I have two outside lamps wired through together so two live and two neutral.
If the old switch had a link wire then yes you will need a link wire.

Usually between the com terminals
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Thanks for your answer andyprk. So would that be black in L1, red in L2 and link the com's? And the linked com's wouldn't affect each other when switches are turned on/off (ie the outside lamps are not affected when the hallway light is switched on/off)?
That's where it gets difficult.

A pic may help.

Are you sure both the red and black were both used before?

Are there any other spare wires?
For the lamps, I only have two red and two black wires. There is an earth but it is not loose as it is already connected. I did have a small red link cable in the old MEM delta switch, which I have used to connect the earth to the plate at the moment.
All wires were used before and there are no spare wires.
Replace the RED link wire were it came from and fit a length of GREEN/YELLOW as the earth link. Do NOT use incorrect coloured cable as it can be lethal.
If you were adding a link, putting it between the two commons wouldn't necessarily be correct.

For a start, the common on the hall switch isn't a true permanent live. As the hall switch is operated, this 'common' wire may go dead for a split second. It will be either the yellow or blue which is the 'true' permanent live.

Are you certain there weren't any separate connector blocks containing some wires at the back of the switch?

Also, I would just like you to confirm that the fuse or circuit breaker didn't blow when you tried the switch?

You should answer these questions before you go any further.
Did you not make a note of how the old switch was wired before you took it off?
Unfortunately I didn't make a note of the previous wiring.
The breaker or fuse did not blow and there were no additional blocks in the socket.
There really is only Plan A or Plan B:

  • Learn how lighting circuits are wired.
  • Get a multimeter and learn how to use it.
  • Identify which conductors are which at the switches and the light positions.
  • Check for voltage present, circuit continuity, switches working etc.
  • Connect everything up properly.
  • Get an electrician.
The thing is you must, you absolutely MUST, understand what you are doing. You must not, under any circumstances, start following instructions to 'insert this wire in that hole' without a full and genuine understanding of why.

Please take some time and learn how lighting circuits and switches work before diving in and trying to do things.

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