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I have a 2 way switch in the garage, set up so that the light can be switched on/off at either end using existing one gang switches.
I want to replace one of these with a 2 gang 2 way switch such that one continues to control the garage light as before and the second one is a simple on/off for a new exterior light. I need the power for this exterior light in the second switch to come from the original light.
I'm sure this is possible, but i can't figure out how to do it. I think I need to bridge one or more of the connections from the original 2 way switch. This is currently wired with red wire to COM, Blue to L1 and Yellow to L2. There's an earth connected to the back of the switch box mounted to the wall.
I have the blue, brown and earth wire from the new light at the switch and a 2 way 2 gang switch
Is it possible, and if so, how do I do it?
You can take the live feed from the red COM across to a terminal on the switch for the exterior light but you need a neutral from elsewhere (usually at a ceiling light fitting) for it to work.
You're most likely best off running a twin and earth from the garage light to the exterior light, then use the cable from the exterior light to the switch as live feed to the switch and switched live back to the fitting lamp.
If that doesn't make sense you're best off calling an electrician TBH
Thanks, can I take the neutral from any other ceiling light? There's one adjacent where I can access all the wiring. If so, where would I take that neutral to? Join it to the neutral from the external light with a terminal block, and then run that into the switch?
The neutral just goes to a terminal for one side of the lamp in the external fitting, you don't need to take it to the switch. The cable to the switch is the permanent live (brown) and the switched live return to the lamp (blue with some brown sleeving or tape to identify it as a live conductor)
Thanks, Davosaurus, got it 8)
Erm.... Thought I had got it, but the new light on the one way switch only works when the light on the two way switch is on. I'm obviously doing something wrong. When I try other combos, the circuit breaker trips, so just to recap I have a 2 gang-2-way switch.
Switch 1 is an existing 2 way circuit in the garage. Red wire to COM, Blue to L1, Yellow to L2. Everything on that switch works fine with the other switch on the 2 way circuit.
I've added new light to run off Switch 2 on the 2 gang circuit. I've taken a neutral off the the garage light and joinsed this into the neutral wire from the exterior light. And then taken that neutral to Switch 2, where I have a live and an earth.
EDIT as I had description wrong! I bridged a wire from COM on switch 1 to L1 on switch 2, then put my brown from live to COM on switch 2 and the Neutral blue wire to L2. The outside light on switch 2 works, but only when switch 1 is on. When switch 1 is off, the outside light is off regardless of switch position.
I've obviously got something wrong! Either my bridge wire is to the wrong port on switch 2 or my live and neutral wires are in the wrong place. Can Davosaurus or anyone else tell me what wires should go where in Switch 2?
Thanks!
You've taken the feed for the outside light from the wrong switch on the two way circuit (one com will be live from consumer unit, other com will be switched to the lamp)
Neutral should not be wired to the switch unless its double pole switched (unlikely for a normal lighting circuit)
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Ah...... So no way to get any juice to the piggy back switch from that end of the 2 way circuit when the switch is off? Would taking the bridge from other than COM on switch 1 solve the problem?
Edit: I'd figured that about the neutral after posting and had disconnected it
Not only that but you are trying to switch the neutral which is causing a dead short between live and neutral and tripping the breaker. You don't switch the neutral, only the live! Like I said you don't even need the neutral at the switch. If you don't have a multimeter get someone in before you burn your house down. No offence, like.
No, the only place to find an unswitched live would be the com on the left switch.
Thanks, Dave, I'd realised that and disconnected the neutral at the switch after I thought about it.
Wot snaps said.
You can take the live from the COM on the LHS switch which I assume is your switch 1 but not switch 2 on the RHS as you say.
If you've taken a neutral from the garage light to the exterior light you are much better off taking the unswitched live to the exterior light as well, that then goes to switch 2 in the 2 gang switch and back to the exterior light again. That is the more usual way of doing it
I need to stop watching telly when typing
Success. I hadn't fully understood the terminology that the more electrically competent were using, but once I thought it through overnight I got it figured out and all working now using Davosaurus's second suggestion in his original post. Thanks to Davosaurus and Snaps 🙂