2 gang 2 way switch

[sturoy]

I have 2 circuts in my living room, each of which has a switch at each end of the room. I used to have a double switch at each end, but have changed them to dimmer switches. However, now the switches don't work properly!!

If I use switch A to turn the lights on, I can only use swtich A to turn them off. If I use switch B to turn them on, I can only use B to turn them off. A and B do not work in conjunction like they should.

What have I done wrong with the wiring!? There are 3 terminals, L1, L2 and common. Have I got them in the wrong places?

 

[riveralt]

I have 2 circuts in my living room, each of which has a switch at each end of the room. I used to have a double switch at each end, but have changed them to dimmer switches. However, now the switches don't work properly!!

If I use switch A to turn the lights on, I can only use swtich A to turn them off. If I use switch B to turn them on, I can only use B to turn them off. A and B do not work in conjunction like they should.

What have I done wrong with the wiring!? There are 3 terminals, L1, L2 and common. Have I got them in the wrong places?

For normal dimmers you cannot put two on the same circuit.
It is difficult to quite understand what you are saying but have you put a double dimmer at both ends?
And you say that you have 2 circuits in the room but you don't describe them as such.
Pictures of how you wired them would be helpful.

 

[TicklyT]

A misplaced wire is certainly a possibility. You did make notes about which wire was where before removing the old switches, didn't you?.

Do both the old switches and dimmers follow the same terminal labelling convention?

Do the lights work correctly if you replace the old switches?

Do the lights work correctly using one dimmer and one switch?

Dimmer set-ups for 2-way switching often require one master dimmer, and a slave units at the second (and subsequent) switch positions, not two or more identical dimmer switches. The wiring between these dimmers is different too.

Trying to operate two dimmers as conventional 2-way switching is fraught with problems as each will try to modulate the output of the other, leading to unpredictable results.

 

[sturoy]

Ah, that will be my problem then - I didn't realise you can't have 2 dimmers. What is the normal solution then? To have one dimmer set, and one normal switch? Or does that not work either? Thanks

 

[RMS]

Yes, remove one of the dimmers and replace with a standard switch.

 

[riveralt]

Ah, that will be my problem then - I didn't realise you can't have 2 dimmers. What is the normal solution then? To have one dimmer set, and one normal switch? Or does that not work either? Thanks

One dimmer and one two way switch is okay.

If it is a normal two way (single circuit) then at one switch there will be three conductor wires (excluding the earth) and at the other five conductor wires (excluding earth).

At the switch with five wires, the live goes in L1 the switch live goes in L2. The other three wires should go into C, L1 and L2 (remember which goes where). At switch two, put the three wires into the same terminals as the first switch. Make sure earths are connected as appropriate.

 

[sturoy]

Thanks very much, all very helpful. Back to B&Q again then!! All of the earths appear to be already attached to the casing.