Lighting puzzle

[trojanhawrs]

It doesn't really matter as per the diagram which side the light's on. 2 cores between intermediate and light 1 switch 2, 2 cores between light 1 switch 2 and switch 1. What's more problematic, is the first switch in the line will swap states on both lights

Never mind I read it wrong, I think he's got it. Edit : No, it does swap both.

 

[EFLImpudence]

Even if he does have it, I still don't think it is possible to do under the conditions of the puzzle.

 

[trojanhawrs]

Even if he does have it, I still don't think it is possible to do under the conditions of the puzzle.

It'd be in the conditions I reckon, doesn't say anything about not making links in the switch boxes. It definitely doesn't work as drawn though

 

[sparkwright]

As I understand it, we can alter things in the switch boxes, but we CANNOT run additional wires anywhere (even though it is in conduit).
I would say links in the switch boxes would be more than acceptable.

 

[EFLImpudence]

Yes, switch A changes supply at switch D, so

to run properly it requires another strapper.

 

[SUNRAY]

You use the existing yellow strappers twice

They also feed the intermediate for light 2

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

 

[SUNRAY]

There is a solution I encountered on a new developement where the electrical contractor followed the consultants original spec to a detail (after informing them it wouldn't work and receiving the common snobbish consultants reply) by using T&E strappers and one way switches.

 

[sparkwright]

There is a solution I encountered on a new developement where the electrical contractor followed the consultants original spec to a detail (after informing them it wouldn't work and receiving the common snobbish consultants reply) by using T&E strappers and one way switches.

Can you explain a bit further?
(Do you mean it won't be a true 2 way system?)

 

[trojanhawrs]

Can you explain a bit further?
(Do you mean it won't be a true 2 way system?)

I think he means it didn't work, just being a cryptic nob about it.

 

[sparkwright]

I think he means it didn't work, just being a cryptic nob about it.

Ah.

 

[sparkwright]

Looking forward to seeing Endecotp's thoughts/solution on this.

 

[securespark]

I think he means it didn't work, just being a cryptic nob about it.

No need to be rude about it, though, is there?

 

[SUNRAY]

Can you explain a bit further?
(Do you mean it won't be a true 2 way system?)

No it didn't work as a 2 way system, it simply used two 1 way switches which was totally inappropriate

I think he means it didn't work,

Correct

just being a cryptic nob about it.

Certainly not, just saying the consultants came up with the spec and the design and the components list.
The contractors informed them it wouldn't work.
The consultants reminded them who the consultants are, so the contractor followed the detailed instructions... as unfortunately how it has to happen far too often.

Personally when I find myself in that position I'll try to put everything in place to do it properly but leave it in the condition demanded by the consultants spec, in order to make the later corrections as easy as possible.

As an example I was asked to look over a comercial AV job prior to cable pulling started, I saw there were 30 video tie lines but only 4 audio running virtually the whole length of the building - over 250 metres, I mentioned this to my supervisor who emailed the consultant.
Their reply to the email was a simple 3 words in capital letters: I'M THE CONSULTANT.
In the meantime I booked out 20 drums of cable to deliver them to site and phoned the installers (team of about 20 due to the distance involved) to advise them there were more cables to be included. and the ends to be discretely coiled and hidden away out of sight.
I asked for printed copies of the email interchange and appended them to the site file when I first worked on site.

During commissioning (my official involvement in the job) which involved the customer and consultant for witness testing and setting up for an event a couple of days later, the customer soon discovered the defficiency and looking through the file the emails came to view.
Our quote to get the big team back in to provide 20 more audio circuits was over £9K of which the customer (a bank) insisted the consultant covered the major part of the cost.

Another job was installing stage lighting bars and dimmers, I suggested providing various DMX cables but told no as not specified and not costed. While the ceilings were out and scaffold towers in place I of course put some cables in, 5 in total. When I returned 16 months later to make some changes, including providing some DMX circuits meant terminating 3 of the cables. Due to the way that job was funded (basically not by the venue) I'd included the additional materials in my original expenses and the venue were delighted the alterations were a bargain.

 

[trojanhawrs]

No need to be rude about it, though, is there?

If you read further up, he slated another poster for giving it a go and getting it wrong, I was just offering my own unconstructive feedback.

 

[endecotp]

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:

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:

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:

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:

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!