Advice on wiring an intermediate light switch where the live/switched live go to the intermediate switch

[michael123123]

The wiring diagrams I can find all show the live/switched live from the light fitting entering the switching circuit at one of the 2-way switches, e.g. here and here.

In my case, I've added a 3rd switch to control one of my lights, but due to the location of the light and the switches, it is such that the live/switched live from the light fitting enter into the backbox of the intermediate switch.

Can anyone please advise on how to wire up the switches in this situation?

 

[Murdochcat]

Tbh I’m not sure it’s possible

Where are you getting the neutral from ?

 

[EFLImpudence]

You can connect the live and switched live at any point on the appropriate conductor

 

[ericmark]

There are switched that only need three wires, and seen one only needing two wires, but these are electronic switches, not mechanical.

And with electronics you don't need any wires. I did fit a smart switch to dinning room when temporary used as bedroom, and used a magnetic backed button on bed to turn lights on/off, however found voice control better so used the push button elsewhere.

 

[michael123123]

You can connect the live and switched live at any point on the appropriate conductor

So to clarify, I can use the L1 and L2 in the intermediate switch?

 

[EFLImpudence]

Yes. Both on the same end of the intermediate.

 

[EFLImpudence]

So to clarify, I can use the L1 and L2 in the intermediate switch?

L1s OR L2s in this diagram:

 

[michael123123]

L1s OR L2s in this diagram:
...

Oh yes - I've had a closer look at the connections in the diagram rather than just the labels. I see what you mean, thank you.

 

[michael123123]

So at long last, the intermediate switch arrived in the post, and I have spent a long time this afternoon unsuccessfully trying to wire it up.

I attach 3 pictures of the 3 switches in question. There's a downstairs 2-way switch at the bottom of the stairs, an intermediate switch at the top of the stairs (this used to be a 2-way switch and is where the 2 core and earth cable from the light fitting appears) and there is a new 2-way switch upstairs at the other end of the landing.

In the depicted configuration, when both of the 2-way switches are in the off correction: "on" position, the lights are on and the intermediate switch does nothing (the lights don't even flicker off when you carefully place the switch half-way between on and off).

I note that the MK intermediate switch I am using has the L1s and L2s in a different configuration. When the switch is in the "off" position, the terminals are connected vertically and when in the "on" position, they connect diagonally opposite top-to-bottom.

What more can I do to troubleshoot?

 

[Murdochcat]

Where are the cores linked at the intermediate that do not connect to the switch ?

 

[EFLImpudence]

Yes, a Brown and a Red according to your pictures.

 

[michael123123]

Where are the cores linked at the intermediate that do not connect to the switch ?

Yes, a Brown and a Red according to your pictures.

They are connected with a wago connector behind the surface mounted back box. I've checked that there is continuity between the two ends of this core that connects the 2 2-way COMs.

 

[Murdochcat]

I've checked that there is continuity between the two ends of this core that connects the 2 2-way COMs.

Then you’ve mixed up some of the cores. A spark would do dead tests to confirm it’s all ok

 

[EFLImpudence]

Most likely being at the switch with three reds.

 

[michael123123]

I should add, I did spend some continuity testing all of the red cores in the 3-core cable between the intermediate switch and the downstairs switch. I placed either 1, 2 or 3 brown sleeves at the end of each core so that I can tell which is which. I will repeat my continuity tests, however, to double check I've got it right.