Strange One

hightower · Apr 29, 2016

Bit of a strange one.

2 pendants that (apparently) used to work as such until one of the switches was rewired by a friend of theirs:

Switch 1, 2 gang
Switch 2, 1 gang

Switch 2 and one of the gangs of Switch 1 work in tandem to create 2-way lighting. Either switch turns BOTH lights on and off, as standard two way. The remaining gang on Switch 1 turns ONE of the lights on and off independently.

Now, I think she's getting her wires crossed somewhere, I'm going to draw it out when I get in later on but I can't see it working from what I can map out in my mind. I think maybe 1 of the lights worked on a 1-way switch, and the other light worked on a 2-way switch. This is in a living room, so I wonder if it's an old dining room knocked through.

Just thought I'd ask for thoughts before I get in and have chance to draw it out. At both switches there are 5 cores - a 3 core and a 2 core each. My guess is Switch 2 has the 2 core as the feed and the 3 core as the strappers, going to the 3 core at switch 1, and feeding one light. Then the remaining 2 core at switch 1 will be a switch drop for the other light.

Will get a chance to test it properly sometime and figure out what goes where, but can't stop thinking about it for now.

telectrix · Apr 29, 2016

hmm. don't take a customer/ friend/relations assessment of the situ. wait till you see it and then make your own assessment of what does what and if, and then suss it out.

hightower · Apr 29, 2016

telectrix said:
hmm. don't take a customer/ friend/relations assessment of the situ. wait till you see it and then make your own assessment of what does what and if, and then suss it out.

Does it sound like anything you've heard of though?

telectrix · Apr 29, 2016

nope.methinks they're confused.

Pete999 · Apr 29, 2016

hightower said:
Bit of a strange one.

2 pendants that (apparently) used to work as such until one of the switches was rewired by a friend of theirs:

Switch 1, 2 gang
Switch 2, 1 gang

Switch 2 and one of the gangs of Switch 1 work in tandem to create 2-way lighting. Either switch turns BOTH lights on and off, as standard two way. The remaining gang on Switch 1 turns ONE of the lights on and off independently.

Now, I think she's getting her wires crossed somewhere, I'm going to draw it out when I get in later on but I can't see it working from what I can map out in my mind. I think maybe 1 of the lights worked on a 1-way switch, and the other light worked on a 2-way switch. This is in a living room, so I wonder if it's an old dining room knocked through.

Just thought I'd ask for thoughts before I get in and have chance to draw it out. At both switches there are 5 cores - a 3 core and a 2 core each. My guess is Switch 2 has the 2 core as the feed and the 3 core as the strappers, going to the 3 core at switch 1, and feeding one light. Then the remaining 2 core at switch 1 will be a switch drop for the other light.

Will get a chance to test it properly sometime and figure out what goes where, but can't stop thinking about it for now.

DIY Dave been on the plot??

snowhead · Apr 29, 2016

I'd guess it was set up so that the 2 way switching (1 gang plus gang 1) always turned 1 light ON , but would turn both lights OFF depending on the position of gang 2.

Adam W · Apr 29, 2016

It should be pretty straightforward once you're there looking at it.
It sounds like the feeds are looped at the roses, each 2 core being a feed and switched live, one at each plate, which will become apparent once you open them up.

lews123 · Apr 29, 2016

Are you sure it was the friend that carried out the work? :yesnod:

hightower · Apr 29, 2016

lews123 said:
Are you sure it was the friend that carried out the work? :yesnod:

I'm not sure what you're insinuating

lews123 · Apr 29, 2016

I'm insinuating that "someone" has took off the light switch for replacement and went "errrr F***... lucky dip time"

hightower · Apr 29, 2016

lews123 said:
I'm insinuating that "someone" has took off the light switch for replacement and went "errrr F***... lucky dip time"

Well yes, I quite agree. But if you're insinuating it was me, well let me tell you that I like magic but messing with a system I haven't even seen is beyond even me.

lews123 · Apr 29, 2016

hightower said:
Well yes, I quite agree. But if you're insinuating it was me, well let me tell you that I like magic but messing with a system I haven't even seen is beyond even me.

Arhh now you're insinuating about what I was insinuating about....

Richard Burns · Apr 29, 2016

Without a relay or a double pole switch (in two way!) then you would not be able to have one light controlled by two switches, one of which also controls another light.
if you were trying to do this every time the single light was switched on it would back feed the other light as well.

You could have an arrangement whereby both lights were on the two way switching and one of the lights had another switch in its switched feed so that if both were on this one could be turned off, however it would only be able to be on if the two way switching were on.

Lucien Nunes · May 1, 2016

You can make the override work the other way, so that switch 1 gang 2 forces its light on even if the 2-way is off, by teeing its L1 into the SL from the 2-way, feeding L2 with permanent live, and running the light from the common. I.e. it selects between whatever the 2-way is doing and 'on', without backfeeding the 2-way SL.

Or, if you want to be really perverse, you could have a kind of Y-shaped 2-way, where the PL goes in at the common of the single gang S2, two strappers run to the L1 & L2 of both gangs of S1, and the two lights run from the two commons. Whatever the state of S2, you have individual control of the two lights from S1. And if the two gangs of S1 are in the same position you have combined control from S2. The problem is that when you want to control from S1 and the two gangs of S2 are in different positions, S1 will turn one light off and the other on.

hightower · May 1, 2016

Lucien Nunes said:
You can make the override work the other way, so that switch 1 gang 2 forces its light on even if the 2-way is off, by teeing its L1 into the SL from the 2-way, feeding L2 with permanent live, and running the light from the common. I.e. it selects between whatever the 2-way is doing and 'on', without backfeeding the 2-way SL.

Or, if you want to be really perverse, you could have a kind of Y-shaped 2-way, where the PL goes in at the common of the single gang S2, two strappers run to the L1 & L2 of both gangs of S1, and the two lights run from the two commons. Whatever the state of S2, you have individual control of the two lights from S1. And if the two gangs of S1 are in the same position you have combined control from S2. The problem is that when you want to control from S1 and the two gangs of S2 are in different positions, S1 will turn one light off and the other on.

Lucien, I've had far too much to drink to take that in. ..... but first thing tomorrow I'll be back to re read

Lucien Nunes · May 1, 2016

If you think about these two options and the one RB describes as a logical truth-table, you will see that no matter how stupidly it is wired, they are the only possibilities for S1 gang 2 if it actually does something. The specially-controlled light can either be forced off (RB's scheme); on (my first scheme); or to the opposite state to the 2-way (my second scheme*). The only remaining possibility is to force it to the same state in which case the switch does nothing at all.

* strictly speaking a variant of this scheme, using an intermediate as S1 gang 1, with the 2-way light teed into one outgoing strapper so that it functions as 2-way with S2, but both strappers continuing to a 2-way switch as gang 2 with the light fed from the common. Then, both gangs of S1 control the special light, gang 1 as 2-way with S2, gang 2 then selects 'same or different' to the 2-way light. Yes you would need a grid switch, no it's not very sensible!

Lucien Nunes · May 1, 2016

Simples!

hightower · May 3, 2016

Lucien Nunes said:
* strictly speaking a variant of this scheme, using an intermediate as S1 gang 1, with the 2-way light teed into one outgoing strapper so that it functions as 2-way with S2, but both strappers continuing to a 2-way switch as gang 2 with the light fed from the common. Then, both gangs of S1 control the special light, gang 1 as 2-way with S2, gang 2 then selects 'same or different' to the 2-way light. Yes you would need a grid switch, no it's not very sensible!

I've tried drawing this out but it's giving me a headache - I don't suppose you (or anyone else) can draw it to help me get my head around the logic?

Thanks,

andyb · May 3, 2016

Unless I've totally miss read this thread (not unusual for me) it looks to me like a simple switching arrangment.
The 2 core at the 1 gang will be a live and switch return, so l1 and l2, the 3 core goes to one of the switches at the 2 gang. The 2 core at the 1 gang is a live and switch return for the other switch.

Sent from my SM-T700 using Tapatalk

andyb · May 3, 2016

Just re read the op on my pc not my tablet. I had misunderstood the problem.

My guess is now that the owner is confused and it never worked as described.

Lucien Nunes · May 3, 2016

I think that too, but there are various ways that it might have been wired and I've sketched the permutations below. SL1 is always ordinary 2-way and SL2 is also controlled independently in various gimmicky ways - I'm not saying any of them are particularly useful or sensible. Obviously the PL & SL might have been taken to different ends compared to how I've shown them.

Now we get to the question - What do they want it to do and can we arrange it with the available cables?

GEOFF S · May 3, 2016

hightower said:
Bit of a strange one.

2 pendants that (apparently) used to work as such until one of the switches was rewired by a friend of theirs:

Switch 1, 2 gang
Switch 2, 1 gang

Switch 2 and one of the gangs of Switch 1 work in tandem to create 2-way lighting. Either switch turns BOTH lights on and off, as standard two way. The remaining gang on Switch 1 turns ONE of the lights on and off independently.

Now, I think she's getting her wires crossed somewhere, I'm going to draw it out when I get in later on but I can't see it working from what I can map out in my mind. I think maybe 1 of the lights worked on a 1-way switch, and the other light worked on a 2-way switch. This is in a living room, so I wonder if it's an old dining room knocked through.

Just thought I'd ask for thoughts before I get in and have chance to draw it out. At both switches there are 5 cores - a 3 core and a 2 core each. My guess is Switch 2 has the 2 core as the feed and the 3 core as the strappers, going to the 3 core at switch 1, and feeding one light. Then the remaining 2 core at switch 1 will be a switch drop for the other light.

Will get a chance to test it properly sometime and figure out what goes where, but can't stop thinking about it for now.

Hi

Maybe it was wired as a two way, the switched live supplied the first pendent and then looped through the switch then onto the second pendent, this would give you the option of both lights on and the ability to switch one off.

Cheers

hightower · May 3, 2016

Lucien Nunes said:
Now we get to the question - What do they want it to do and can we arrange it with the available cables?

Hopefully this helps explain things - this is how it's currently wired, a straight forward 2-way switch for one light, and a 1-way switch for the other. Each box has a 2-core and a 3-core entering. Now, apparently this used to be wired (many moons ago) so that S1 could individually control both lights (as it can wired like this), but rather than S2 only turning on/off the right hand light it should turn on/off both.

Now, I haven't done any circuit design yet as part of college, but I can join the dots and as far as I can work out, RB is correct when he says to achieve something like this you would need to introduce electronic components etc

Richard Burns · May 3, 2016

Lucien Nunes said:
I think that too, but there are various ways that it might have been wired and I've sketched the permutations below. SL1 is always ordinary 2-way and SL2 is also controlled independently in various gimmicky ways - I'm not saying any of them are particularly useful or sensible. Obviously the PL & SL might have been taken to different ends compared to how I've shown them.

I love the split two way, that would cause major headaches!!