Two lights onto one-gang two way switch?

[wojb]

Hi,

I have got two lights in my hall - one at the bottom and one on top of the stairs. I was stupid enough not to take photos of wiring before I took downstairs switch off and now struggle to wire it in properly. It was two gang, old switch (marked A, A1, A2, B, B1, B2).

Upstairs box has got three wires in it, black, black and red. One of blacks goes into common terminal and the other two (B & R) go to L1 and L2 (it is a one-gang switch). I have never touched this switch.

Downstairs I have got four wires - two black and two red. Before I took it off, it was wired in a way that downstairs light could only be operated by switch downstairs (one of switches on two-gang), and upstairs was a two-way system operated by other switch downstairs or the one upstairs.

I can remember that when I took the downstairs switch off, there was a bridge between two terminals - I don't have a clue which ones.

I am now wondering if I can put one-gang switch downstairs as well, and make both lights go on and off at the same time, using two way switch (both upstairs and downstairs would be one gang).

I have got some experience with electrics but this seems a bit complicated to me... Anybody help?

 

[ban-all-sheds]

Downstairs I have got four wires - two black and two red.

One pair will be the ones going to the upstairs switch, the other will be for the downstairs light.

Before I took it off, it was wired in a way that downstairs light could only be operated by switch downstairs (one of switches on two-gang), and upstairs was a two-way system operated by other switch downstairs or the one upstairs.

Yup - incredibly common - done like that in millions of houses.

The downstairs half of the switch has a normal switch drop cable, the upstairs half is wired like the top left drawing here: //www.diynot.com/wiki/electrics:two-way-lighting.

I can remember that when I took the downstairs switch off, there was a bridge between two terminals - I don't have a clue which ones.

You'll see from that diagram that there needs to be a permanent live connected to the COM of the switch - that would have been provided by a link from the permanent live in the downstairs light switch cable. PROBABLY in COM (or in your switch A or B), but not necessarily - depends how it was wired (1-way switches don't care which way round permanent and switched live go).

I am now wondering if I can put one-gang switch downstairs as well, and make both lights go on and off at the same time, using two way switch (both upstairs and downstairs would be one gang).

Not with the current wiring - if you did, then the downstairs light would work as it did before, and it would still only be controlled by the downstairs switch, but you would have made it so that the upstairs light was also controlled by the same switch, i.e. that downstairs switch would also flip the state of the upstairs light. So if both lights were on, and you used the one in the hall to turn off the hall light when you go to bed, you'd be plunged into darkness, which might not be what you want.

I have got some experience with electrics but this seems a bit complicated to me.

It shouldn't be, really.


//www.diynot.com/wiki/electrics:lighting

BTW - I hope you only have 1 lighting circuit, not split upstairs/downstairs?

//www.diynot.com/wiki/electrics:sneutral

 

[wojb]

I am going to check which wires go to upstairs switch with multimeter later on today.

Not with the current wiring - if you did, then the downstairs light would work as it did before, and it would still only be controlled by the downstairs switch, but you would have made it so that the upstairs light was also controlled by the same switch, i.e. that downstairs switch would also flip the state of the upstairs light. So if both lights were on, and you used the one in the hall to turn off the hall light when you go to bed, you'd be plunged into darkness, which might not be what you want.

That is what I want - I turn on the lights with downstairs switch (both lamps go on), I go upstairs and turn them both off with one switch. Or the other way round - turn them on upstairs and and off downstairs. I do not require separate control for up- and downstairs lights.

 

[ban-all-sheds]

I am going to check which wires go to upstairs switch with multimeter later on today.

Then you'll be sorted.

That is what I want - I turn on the lights with downstairs switch (both lamps go on), I go upstairs and turn them both off with one switch. Or the other way round - turn them on upstairs and and off downstairs.

Not with the current wiring - if you did, then the downstairs light would work as it did before, and it would still only be controlled by the downstairs switch, but you would have made it so that the upstairs light was also controlled by the same switch, i.e. that downstairs switch would also flip the state of the upstairs light. So if both lights were on, and you used the one in the hall to turn off the hall light when you go to bed, you'd be plunged into darkness, which might not be what you want.

is not what you want. But it is what you'll get if you replace the 2-gang switch with a 1-gang.

You cannot get what you want without rewiring. Look at the Wiki articles and see how it would have to work.