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cjc, Just to add we have no idea of your current wiring set-up, clear pictures of the back of each switch please.

Someone in your house has OCD (this is not an offensive remark - it's something I have come across several times at work). SE has worked out what to do - you just need to swap 2 cables around.

Thanks. I take it you are agreeing with SE, which counts as confirmation. But you say “You just need to swap 2 cables round”. Which two cables – any two cables? Are there only two? Are they called strappers? I’m not trying to be funny: I need to pass on completely unambiguous instructions or else the electrician is liable to pick holes in what I’m saying.

The sort of thing I would like to say is this:

You need to swap the red and blue cables between the A1 and B2 connectors corresponding to the downstairs light. You can do this on either the upstairs switch or the downstairs switch – it doesn’t matter which – but not on both because then you would end up back where you started.

OnlyMe wrote: ↑Fri Jan 05, 2024 7:49 pm Someone in your house has OCD (this is not an offensive remark - it's something I have come across several times at work). SE has worked out what to do - you just need to swap 2 cables around.

But that won't work

If you turn on the upstairs light at the bottom , then off at the top - they will be in different positions

Using standard 2 way switches you can't achieve what she thinks she wants

My upstairs light works in the following fashion:
(A) The light is off if both corresponding switches are in the same position and on if they are in different positions.

My downstairs light works as follows:
(B) The light is on if both corresponding switches are in the same position and off if they are in different positions.

I want my downstairs light to work like (A), not like (B). It cannot be true that using standard 2-way switches I cannot achieve (A) because I have standard two-way switches which already achieve (A) for the upstairs lights.

The question boils down to this: why do some 2-way lights work like (A) and some like (B)? If I know the answer then I know what to change. I assumed that the answer lay in how the switches were wired. If this was not true, then perhaps it would lie in how the light itself was wired, or in the orientation of the switch box, or in the colour of the electrician’s eyes. But there has to be some explanation. Simply saying ‘It cannot be changed because that is how it is wired’ is no answer at all.

I understand Someone-Else and Only-Me to be saying that the answer does indeed lie in the wiring of the switch, and that the simple interchange of two components (cables? strappers?) chooses between (A) and (B). This makes perfect sense since it provides a simple and credible explanation of why my two lights work differently.

If you just swap the strappers the two way will not function properly as a 2 way switch

There is no on or off using standard 2 way switches

Neelix wrote: ↑Sat Jan 06, 2024 11:24 amIf you just swap the strappers the two way will not function properly as a 2 way switch

oh? what does an intermediate switch do then? It swaps the strappers.

Someone-Else wrote: ↑Sat Jan 06, 2024 12:55 pm

Neelix wrote: ↑Sat Jan 06, 2024 11:24 amIf you just swap the strappers the two way will not function properly as a 2 way switch

oh? what does an intermediate switch do then? It swaps the strappers.

There is no on / off on an intermediate either. Just up and down

Someone-Else wrote: ↑Sat Jan 06, 2024 12:55 pm

Neelix wrote: ↑Sat Jan 06, 2024 11:24 amIf you just swap the strappers the two way will not function properly as a 2 way switch

oh? what does an intermediate switch do then? It swaps the strappers.

Let's assume that the OP does not have an intermediate switch.

Neelix wrote: ↑Sat Jan 06, 2024 11:24 am If you just swap the strappers the two way will not function properly as a 2 way switch

There is no on or off using standard 2 way switches

There is if the the person using them wants them to be that way. That is what the OP or someone in their house wants. Reverse the connections on one of the two way switches on L1 and L2 and the job is done.

OnlyMe wrote: ↑Sat Jan 06, 2024 4:04 pmLet's assume that the OP does not have an intermediate switch.

I never said he has. I said

Someone-Else wrote: ↑Sat Jan 06, 2024 12:55 pmwhat does an intermediate switch do then? It swaps the strappers.

still won't work if the switch is changed as I explained earlier ....

There seems to be some disagreement about what happens if the L1 and L2 connectors are interchanged in a two-way switch. This is a purely factual question. It does not depend on the terminology, eg. whether the switch positions are called ‘on’ and ‘off’ or ‘up’ and ‘down’, and nor does it depend on whether the change is desirable or not. It is simply a question of whether the light is on or off when the switches are in given positions (which you can call by whichever names you want).

According to Someone-Else and Only-me the switch will still work as a valid two-way switch, i.e. flipping either switch will flip the light. I think Neelix is denying this. It might be best to resolve the factual question without getting side-tracked into debates about terminology.

I totally understand what you are saying and I know what you are saying with the on/off positions of the light switches (actually Desmond Bagley mentions this in his 1973 novel The Tightrope Men). Swapping the cables at terminals L1 and L2 has the same effect as turning the lightswitch upside down and turning one of the lights switches upside down would achieve what you want