Old light switches wiring

MalcolmS · May 27, 2024

Hi All,
I have these old light switches.
I understand this yellow / blue is the old pre 1980 colour scheme.
Is it correct that:
1. YELLOW with a red sleeve is LIVE
2. BLUE with a red sleeve is NEUTRAL
?
Thanks

ipf · May 27, 2024

No Neutral involved. Any cables with red sleeving should be switched lives, in this case 'strappers' for a 2way light.
Why do you ask? Are you changing the switches?
That back box lug on the 1 gang doesn't seem to be in the best of health.

MalcolmS · May 27, 2024

ipf said:
No Neutral involved. Any cables with red sleeving should be switched lives, in this case 'strappers' for a 2way light.
Why do you ask? Are you changing the switches?
That back box lug on the 1 gang doesn't seem to be in the best of health.

The electronic switch I am adding has "L In" and "L Out" and yes this switch does not require Neutral. "L Out" leads to the bulb.

Yeah the box lug looks loose, it's in a plasterboard wall with a void.

littlespark · May 27, 2024

First switch I presume is a 1 way and a 2 way…
Second switch is the paired 2 way.

Looking at the wiring, you may have a permanent live at both boxes, which could be 2 separate circuits.

Isolate before messing around.

Try to fix the screw lug, or replace the box entirely. Looks broken, not just loose.

If you have an electronic switch… which make? As they can work different ways.

Are you replacing both switches, or just one that controls both lights?

And finally… those are shallow boxes. Will you get an electronic switch to fit? You may need a plastic extension spacer to bring it out from the wall a bit.

ipf · May 27, 2024

MalcolmS said:
The electronic switch I am adding has "L In" and "L Out" and yes this switch does not require Neutral. "L Out" leads to the bulb.

Yeah the box lug looks loose, it's in a plasterboard wall with a void.

Just get a pro in to sort it, Malcolm.

I see you're in London, though. A couple of hours' all in......£400ish???

Oh, Plus a tenner for mats.

MalcolmS · May 27, 2024

littlespark said:
First switch I presume is a 1 way and a 2 way…
Second switch is the paired 2 way.

Looking at the wiring, you may have a permanent live at both boxes, which could be 2 separate circuits.

Isolate before messing around.

Try to fix the screw lug, or replace the box entirely. Looks broken, not just loose.

If you have an electronic switch… which make? As they can work different ways.

Are you replacing both switches, or just one that controls both lights?

And finally… those are shallow boxes. Will you get an electronic switch to fit? You may need a plastic extension spacer to bring it out from the wall a bit.

Yes, you are right, two separate circuits (upstairs, downstairs lights) but in 2-way configuration across 2 circuits.
Yes, I am going to fix the box lug
Yes, well spotted I will need the extension spacer for the shallow one.
Yes, same electronic switch per box
This is the diagram of the electronic switch.

[ElectriciansForums.net] Old light switches wiring

Avo Mk8 · May 27, 2024

Malcolm - I'm not sure what your question is!

Use the top left wiring diagram for putting one Sonos with the single switch, establish which of those two wires is permanent (L), wire then accordingly to the Sonos L terminals, and then wire the switch directly to S1 & S2.

Use the top right diagram to wire the 2-way switch, reconfiguring the 3 core cable to mimic that diagram. Put the other Sonos with this switch. Establish which of the two non-3 core conductors is permanent (L) as before, and wire that to the Sonos Lin as before, the other wire to Lout. Then wire the 3-core to match the circuit diagram for the S1 & S2 connections.

If you don't have test equipment, or are uncertain about implementing the diagrams, you may need some help.

MalcolmS · May 30, 2024

I have checked all the wires with a multimeter and the ones marked in violet colour are permanent lives. Permanent lives in each box are red and indistinguishable from the other red ones.

# 1-WAY SWITCH (upstairs)
COM - yellow (with red sleeve)
WAY L1 - blue (with red sleeve) + red -> permanent live
WAY L2 - 2x red

#2-WAT SWITCH (downstairs)
BOTTOM
COM - yellow (with red sleeve)
WAY L1 - red -> permanent live

TOP
WAY L1 - blue (with red sleeve)
WAY L2 - red
COM - red

From what I red online COM supposed to be LIVE (PERMANENT) and L1 should be SWITCHED LIVE but in this case permanent goes to L1 in both boxes.
Does it makes sense to you or is it mixed up?

ipf · May 31, 2024

We can see what is going on from your photos. You obviously don't understand the 2-way wiring method involved.
Don't take as red all you reed online.
As above (and previously) professional help is advised.

Avo Mk8 · May 31, 2024

You misunderstand the terminals of the switches, or if you don't, you chose a bizarre way of representing the information in your table of results. Each switch has terminals in a triangle, as I've tried to show in the second pic below.

So unravelling your list, you have traditionally wired circuits, nothing is mixed up.
It's like this for the two-way circuit:

It needs to be wired as I suggested previously.
In order to implement the 2-way Sonos circuit, the upstairs wiring to the switch will have to be changed.
If you are not sure how to do this, do get some help, as there is plenty of opportunity to blow up the Sonos device, have an accident, or leave something dangerous behind.

davesparks · May 31, 2024

MalcolmS said:
From what I red online COM supposed to be LIVE (PERMANENT) and L1 should be SWITCHED LIVE but in this case permanent goes to L1 in both boxes.

From what I've read online the earth is flat and run by giant lizard people who live underground.

Don't believe what you read online.

There is no 'supposed to be' as far as the terminals on those switches are concerned. Com, L1 and L2 are just three terminals on a switch which will be connected differently depending on how they are being used, for extra fun different manufacturers sometimes label them differently.

MalcolmS said:
Does it makes sense to you or is it mixed up?

Makes perfect sense to me.

MalcolmS · Jun 7, 2024

Hi again Everyone,
You were helpful to me especially Avo Mk8 is very understanding. I made this diagram.
Perhaps you will say it's wrong

So far I connected the switch downstairs, it works, I left the blue and yellow wires aside for now but for some reason I lost the current upstairs, not sure why. It's on a separate circuit, the RCB is ON but no lights upstairs.

Avo Mk8 · Jun 7, 2024

MalcolmS said:
So far I connected the switch downstairs, it works, I left the blue and yellow wires aside for now but for some reason I lost the current upstairs, not sure why. It's on a separate circuit, the RCB is ON but no lights upstairs.

Your diagram is of how the old switches are/were wired, and as far as I can see, is correct.
It does not represent how to connect the Sonos.

With the yellow and blue wires disconnected, the light will never come on because you have removed the way the bulb gets power.

The Sonos needs to be connected as per the top right diagram in your post #6.

This forum is not supposed to give step by step instructions for obvious reasons.
I'm feeling that since you are already involved in this, somewhat against the advice already given, I will give a factual explanation of the necessary wiring. It needs to be carried out safely and competently, which you need to organise.

The red wire to the upstairs light bulb should be in Sonos L out, and the incoming power (circuit 2) red wire should be in Sonos L in.

The end of the yellow wire that used to be in upstairs switch com (that you say is presently unconnected) should be in Sonos S2.

The blue wire (that you say is presently unconnected) should go to the upstairs switch L1 where it was originally.

A short piece of insulated wire is needed between the upstairs switch Com and Sonos S1.

The end result should be that there is only one wire in each old 2-way switch terminal, and only one wire in each Sonos terminal.

MalcolmS · Jun 7, 2024

Ok, thanks again.
I meant the lights not only in the hallway but across the whole 1st floor are gone.
RCB says "lights+smoke detector". When that RCB is on I can see the green light on the smoke detector but other than that no power to any of the lights. When off the green light on the detector goes off as well. The red wire in upstairs light socket that use to have current is dead now. Did I blow some fuse or the RCB malfunctions?

Avo Mk8 · Jun 7, 2024

MalcolmS said:
Ok, thanks again.
I meant the lights not only in the hallway but across the whole 1st floor are gone.
RCB says "lights+smoke detector". When that RCB is on I can see the green light on the smoke detector but other than that no power to any of the lights. When off the green light on the detector goes off as well. The red wire in upstairs light socket that use to have current is dead now. Did I blow some fuse or the RCB malfunctions?

Oh, I see, I hadn't understood that, sorry.
Difficult to diagnose remotely.
Is the individual Breaker that tripped, an MCB, RCBO or an RCD. Unusual to be the latter for an individual circuit?
If switching the 'RCB' causes the smoke detector light to be on/off, sounds as if the breaker is providing power when on.
Is there some other protective device on your lighting circuit? Nothing else tripped?

Have you put the wires back in the upstairs switch exactly as they used to be, and if so does that restore power? There might be a link to those cables somewhere we don't know about?

Old light switches wiring

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