Question about light switch wiring

[Tony_Kent]

I've a five-story house, with an awful lot of light switches in it. Some are two-way, some are one way.

I thiought that I understood the wiring in the switches for each, but looking at some I'm getting confused.

For example, I've a one-way switch that is the only one to control one group of ceiling lights. I'd expect one live wire to go into one side of the switch, and one switched live to cone out of the other side. The other input to the switch should be empty.

What I actually have is two wires coming in to the bottom, one live, and one with no voltage (so it could be a neutral, an Earth, or just not attached to anything.

Like this;

On some of the two-way switches, where I'd expect the switches to have two switched-lives coming in, and one switched live going out, I actually have one wire in the "common" connection, but then two wires going into each of the inputs, with one input having a blue and a black, and the other having a brown and a grey, as shown below.

Is anyone able to explain what's the setup here?

Thanks.

 

[EFLImpudence]

Lighting Circuits Introduction

An explanation of wiring methods and circuit diagrams for various UK lighting circuits

flameport.com

 

[EFLImpudence]

Your pictures all show two-way switches being used on two-way circuits.

Two-way switch - a switch with two outputs; one or other of which is connected to the supply input at any given time.
Two-way circuit - a circuit with more than one switch operating the same light(s).

 

[Tony_Kent]

Your pictures all show two-way switches being used on two-way circuits.

Two-way switch - a switch with two outputs; one or other of which is connected to the supply input at any given time.
Two-way circuit - a circuit with more than one switch operating the same light(s).

Thanks, but as I wrote, they are not two-way. There is no other switch controlling the lights that this switch controls. It turns on two ceiling lights, and no other switch in the house controls them.

THere are several like this, including ones that control a light that no-one would ever want a two-way control for (such as the one in the under-stairs toilet.)

 

[Tony_Kent]

Curiouser and curiouser.

The grey wire is live, the brown is switched live, and so is the black, so it's live when the brown is live, and not when the brown is not.

 

[Murdochcat]

Curiouser and curiouser.

The grey wire is live, the brown is switched live, and so is the black, so it's live when the brown is live, and not when the brown is not.

That photo definitely shows connections for 2 way switching …..

 

[EFLImpudence]

Thanks, but as I wrote, they are not two-way.

Yes they are.

There is no other switch controlling the lights that this switch controls.

What do you mean "this switch"; your pictures show three or four.

It turns on two ceiling lights, and no other switch in the house controls them.

Then the other switch must have been removed.

THere are several like this, including ones that control a light that no-one would ever want a two-way control for (such as the one in the under-stairs toilet.)

Ok.

 

[Murdochcat]

The one in the photo that is definitely a 2 way switch - which light does it control?

 

[SUNRAY]

It is very feasible a spare wire has simply been 'parked' in a spare hole

 

[Tony_Kent]

Yes they are.


What do you mean "this switch"; your pictures show three or four.


Then the other switch must have been removed.


Ok.

The house is an 1850s five-floor townhouse. It spent the last years of the 20th century as Newcastle Council offices and was then stripped back to just the walks and “rebuilt” in around 2010.

There was no electrical work done between then and when I bought it in 2019.

I know that it looks like two-way switching, but as per my testing above, it really doesn’t seem to be.

If it was then one wire in would be live and the other wouldn’t be.

 

[Tony_Kent]

It is very feasible a spare wire has simply been 'parked' in a spare hole

Yes, I think that’s possible.

I can achieve what I want without needing to know for sure what’s going on, but rather wouldn’t.

 

[Tony_Kent]

The one in the photo that is definitely a 2 way switch - which light does it control?

Just one set of ceiling lights in the hall above it.

I’ve operated every other switch in the house and nothing else turns it on or off.

I think the answer is going to be that someone has done something “weird” when presented with some extra wires and that I may as well just terminate them behind the switch.

 

[ericmark]

Taking this picture as an example it would seem likely the brown in with the grey and the blue in with the black are the switch wires and the brown on its own and the grey and black when to another switch, that switch would have mirrored the one show but without the switch wires, so it could be removed and the black or grey connected to brown and unused wire made safe, and the switch shown would then work like a normal on/off switch.

If some one has then hidden the location of the slave switch, this could cause confusion and in fact danger as one could drill through the cable being unaware any cables where there.

I myself have two way switching in the kitchen, and the second switch is hidden behind the freezer, so never used, and I have considered disconnecting it so I can use a smart switch. But still have the use of my fingers so not done it yet.

 

[SUNRAY]

Taking this picture as an example View attachment 332308 it would seem likely the brown in with the grey and the blue in with the black are the switch wires and the brown on its own and the grey and black when to another switch, that switch would have mirrored the one show but without the switch wires, so it could be removed and the black or grey connected to brown and unused wire made safe, and the switch shown would then work like a normal on/off switch.

If some one has then hidden the location of the slave switch, this could cause confusion and in fact danger as one could drill through the cable being unaware any cables where there.
...

It seems this is the most likely situation except its the first switch that's missing. Or maybe it's now a junction box somewhere