How should this double light switch be wired?

[redhexagonal]

I opened up this double switch to add an earth wire from backbox to faceplate, and a wire came loose , the one I’ve highlighted in pink. I thought it went in the common at top left so I put it back there, but when I turned the electric back on the circuit breaker was triggered. Then when I took the faceplate off again another wire came loose, the one highlighted green. i think it goes into L1 at the bottom left, but now I’m not so sure.

There is a short loop connecting the common on each switch.

Can anyone help me connect this properly?

 

[ericmark]

The only wire which has a fixed colour is the green/yellow for the earth, the switch switches between com to L1 and com to L2 with a on/off only wiring L2 is normally not used, and permanent line normally goes to com, however with two way switching it will normally go to L1 or L2.

I have been wondering why getting it in wrong hole would cause it to trip, I wonder if two different circuits and the RCD is what is tripping, I have this with my bottom of stairs switch, I have two permanent line feeds one for down stairs lights and one for upstairs, swapping them around will cause it to trip the RCBO's.

 

[terryplumb]

What exactly tripped ? As the live is bridged across two switches it's unlikely to be an RCD.

 

[redhexagonal]

What exactly tripped ? As the live is bridged across two switches it's unlikely to be an RCD.

I turned on the basement lighting circuit , turned on the RCD switch which is next to that group of switches, and the basement lighting circuit tripped, along with the RCD

 

[redhexagonal]

The only wire which has a fixed colour is the green/yellow for the earth, the switch switches between com to L1 and com to L2 with a on/off only wiring L2 is normally not used, and permanent line normally goes to com, however with two way switching it will normally go to L1 or L2.

I have been wondering why getting it in wrong hole would cause it to trip, I wonder if two different circuits and the RCD is what is tripping, I have this with my bottom of stairs switch, I have two permanent line feeds one for down stairs lights and one for upstairs, swapping them around will cause it to trip the RCBO's.

I rewired several other switches (added earth wires and terminal blocks) on the same circuit, there was a single switch that was connected to COM and L2 even though it is a 1-way switch and was upside down as a result. I switched it for a dimmer and used COM and L1. Could that cause a problem?

 

[terryplumb]

What have you done to allow the breakers to be re set ,if anything ?
Do you have any voltage testing instruments ?
The left switch would need to have one conductor connected to its L1 terminal ,being the switched live to the light fitting it operates. The other would be permanent live that would go into one of the com terminals.

 

[redhexagonal]

What have you done to allow the breakers to be re set ,if anything ?
Do you have any voltage testing instruments ?
The left switch would need to have one conductor connected to its L1 terminal ,being the switched live to the light fitting it operates. The other would be permanent live that would go into one of the com terminals.

I’ve left the switch as it is in the photo with a bit of tape over the exposed wire highlighted green, then turned power back on ok. I do have a multimeter yes. Not sure which connections to measure across though

 

[EFLImpudence]

I agree with your original choice of where to connect the two loose wires.


Either way, even doing it wrong would not cause anything to trip.

Perhaps one of the wires is chafed and touching the backbox when moved.

 

[redhexagonal]

I agree with your original choice of where to connect the two loose wires.


Either way, even doing it wrong would not cause anything to trip.

Perhaps one of the wires is chafed and touching the backbox when moved.

Correct. I had it wired right but the common loop had got caught and damaged by the screw for the plate and shorted out. I think the screws were over long

 

[EFLImpudence]

Oh, right. Had I missed that bit?

Does that mean all is well now?

 

[redhexagonal]

Oh, right. Had I missed that bit?

Does that mean all is well now?

All sorted now ta, Terry gave me a hand testing. I didn’t notice the damaged loop initially

 

[EFLImpudence]