Lighting puzzle

[trojanhawrs]

@endecotp Thanks for the exercise, kept us entertained at least. A few comments on your diagrams.

1) I'm not sure what you've got in the right switch box there, but whatever it is seems a bit cheeky
2) Yep
3) Yep, that would work
4) That's genuinely very clever

 

[SUNRAY]

Thanks for all your posts - I hope you enjoyed the mental exercise! Here are my (partial?) solutions:

Firstly, of course it would be easy if there were a permanent live a the right switch. There isn't, but one or other of the red strappers will always be live. So if we had a DC supply, we could do this:

View attachment 396496

I spent a while trying to invent an AC version of that, and failed. Even with a few transistors I needed a neutral at the right box to make it work. So that was a dead end.

My other ideas all involve an intermediate (crossover) switch in the right box, as suggested by mikehammer69 in post #7 and drawn up by EFLImpudence in post #20. Here's my version of that circuit:

View attachment 396498

Of course as you've noticed that doesn't quite work; you can control both lights from both ends of the room, but the switch for the original lights at the left side now also toggles the new light.

I have a couple of thoughts about how to fix that. Firstly, you could use a DPDT switch to "undo" the unwanted toggle from that switch:

View attachment 396501

The problem with that, of course, is that you can't buy DPDT switches to use in regular wall switch boxes; some nasty bodge would be required with an un-matching switch.

On the subject of nasty bodges... that leads to my final offering:

View attachment 396502

That works in the sense that all the switches do what you want, and it only uses readily available components. The problem is... well, I hope you can spot it!

I'm just wondering how that would be EICR coded

 

[SUNRAY]

I have a couple of thoughts about how to fix that. Firstly, you could use a DPDT switch to "undo" the unwanted toggle from that switch:

View attachment 396501

The problem with that, of course, is that you can't buy DPDT switches to use in regular wall switch boxes; some nasty bodge would be required with an un-matching switch.

At least one manufafturer makes a DP2W euromodule, I think Legrand

EDIT: https://www.legrand.com.eg/en/catal...ole-switch-20-ax-250-v-2-modules-white-572048

 

[pete01]

Thanks for all your posts - I hope you enjoyed the mental exercise! Here are my (partial?) solutions:

Firstly, of course it would be easy if there were a permanent live a the right switch. There isn't, but one or other of the red strappers will always be live. So if we had a DC supply, we could do this:

View attachment 396496

I spent a while trying to invent an AC version of that, and failed. Even with a few transistors I needed a neutral at the right box to make it work. So that was a dead end.

My other ideas all involve an intermediate (crossover) switch in the right box, as suggested by mikehammer69 in post #7 and drawn up by EFLImpudence in post #20. Here's my version of that circuit:

View attachment 396498

Of course as you've noticed that doesn't quite work; you can control both lights from both ends of the room, but the switch for the original lights at the left side now also toggles the new light.

I have a couple of thoughts about how to fix that. Firstly, you could use a DPDT switch to "undo" the unwanted toggle from that switch:

View attachment 396501

The problem with that, of course, is that you can't buy DPDT switches to use in regular wall switch boxes; some nasty bodge would be required with an un-matching switch.

On the subject of nasty bodges... that leads to my final offering:

View attachment 396502

That works in the sense that all the switches do what you want, and it only uses readily available components. The problem is... well, I hope you can spot it!

Looking at number 4 is giving me a headache

 

[endecotp]

At least one manufafturer makes a DP2W euromodule, I think Legrand

EDIT: https://www.legrand.com.eg/en/catal...ole-switch-20-ax-250-v-2-modules-white-572048

Ah! That's interesting. I note it is double width.

 

[SUNRAY]

Well if you are proposing switching live and neutral you have made it far too complicated, it seems you have too many wires in your system

This method has been fairly common, still exists in some places and uses very standed components
One from 2018

2 way lights again (Oh and why I don't like domestics)

"Got a little 2 way switch job for you Sunray" "More rubbish?" "Customer says they changed a switch and now it doesn't work." This is just how I found it: "I took the broken switch off and forgot how it was connected so I went on-line and couldn't find the same numbers of cables." The hall...

www.diynot.com

 

[SUNRAY]

In fact you have enough wires to use 3G switches for 3 lights

 

[sparkwright]

Well if you are proposing switching live and neutral you have made it far too complicated, it seems you have too many wires in your system
View attachment 396527
This method has been fairly common, still exists in some places and uses very standed components
One from 2018

2 way lights again (Oh and why I don't like domestics)

"Got a little 2 way switch job for you Sunray" "More rubbish?" "Customer says they changed a switch and now it doesn't work." This is just how I found it: "I took the broken switch off and forgot how it was connected so I went on-line and couldn't find the same numbers of cables." The hall...

www.diynot.com

I remember this method, and nearly contemplated trying to use it for this puzzle,

 

[SUNRAY]

I remember this method, and nearly contemplated trying to use it for this puzzle,

Likewise that was my first thought and half expected it to be OPs too.

 

[mikehammer69]

How on earth do you expect that to work correctly? Not the sort of solution I'd expect from a longtime spark.

True
The alcohol did play some role

 

[ebee]

Well a very interesting problem.
I did take a look at it a couple of days ago but I was away from home and had no paper so a quick thought mentally was all I could manage.
Only a couple of side-tracks too, so well done.

Unfortunately now I'm back I cant get my printer to work, I was going to print the picture then do a few scribblings , bah humbug.

So I will draw it out today, I`m not IT literate enough to draw it out on my laptop.

Anyway my initial thoughts, it might be possible, the sticking point might be the LH group of singles, if a wire was there in place from the L connection of the two lamps to the LH switch I think it coud be done but without that in place I think it can`t be done.

Either way, thanks for the question.
Lighting circuits usually cause the biggest problems because of the different tricks we can use.

I will rule out the one that swaps the L & N around in the lampholder because it is not in keeping with our regs (probably not important of a bayonet type lampholder itself but on an Edison Screw lampholder is a no no.
I was introduced to the switching polarity to obtain two way switching just a very few years ago, apparently one name for it is the "Two Way Hamburger" no idea if it refers to the practices of the people of Hamburg though!

 

[AndyPRK]

I always consider the polarity change to be an American thing, so more burgers than Germans.

Polarity isn't such a problem on modern ES holders. There are 2 safety features to prevent problems.
1) The metal is enclosed so fingers can't touch it.
2) There are 2 thread rings. The one close to the end has the supply connected to it. The outer one is only connected by the lamp, when the lamp is almost all the way in.

 

[ericmark]

I am sure one can fit a relay at the lights, and use momentary switches, to change the state of the relay.

However, the relay I used to do this was a smart relay, so not permitted. It did not need momentary switched, change of state changed if on or off. And after fitting, I wished I had simply used smart bulbs.

I can't see the point of not using electronics. I remember the control panels of yesteryear, things of beauty, but today a little PLC does it all, easier to install, easier to program, easier to repair, one has to move with the times. How many people remember the hand signals when driving a car, we have moved on.

 

[ebee]

I am sure one can fit a relay at the lights, and use momentary switches, to change the state of the relay.

However, the relay I used to do this was a smart relay, so not permitted. It did not need momentary switched, change of state changed if on or off. And after fitting, I wished I had simply used smart bulbs.

I can't see the point of not using electronics. I remember the control panels of yesteryear, things of beauty, but today a little PLC does it all, easier to install, easier to program, easier to repair, one has to move with the times. How many people remember the hand signals when driving a car, we have moved on.

Eric - I reckon that the OP might have just wanted to do a thought experiment so asked for us to rule out relays and Wifi/Bluetooth sort of IT completely

 

[ericmark]

Eric - I reckon that the OP might have just wanted to do a thought experiment so asked for us to rule out relays and Wifi/Bluetooth sort of IT completely

A latching relay at the lights, would allow use of momentary switches, to change state of the relay. So you have a spare wire which can control the other light. But a latching relay today costs more than a smart relay, so what is the point?