Two-way and intermediate switches

[John]

I'm no electrician but my mate reckons that you can have as many intermediate switches as you want on a two-way circuit (think switching the landing light on downstairs before going to bed but it's a long landing with six rooms - he wants each room to have its own switch on the landing).

I reckon that you can have the two two-way switches as normal, with one intermediate switch. Who's correct - and if he's right, and you can have more than one intermediate switch, can anyone give a wiring diagram (preferably not ASCII as I can never make head nor tail of them)?

Cheers and TIA

[Tim Watts]

John wibbled on Wednesday 30 June 2010 20:37

You can have zero or more intermediate switches.

Think about it:

Normal 2-way means that you send voltage either wire A or wire B. The lamp lights if both switches are set to both Wire A *or* both wire B.

The intermediate switch is a funky little beast (that doesn't exist in any normal equipment switch range say in Maplin or RS) that swaps wire A and B over.

Each time you swap A and B you change the state of the lamp, but the end switches can still also change the state of the lamp.

You can therefore have as many swappers (int switches) as you like, subject to resistance constraints.

Cheers

Tim

[Bob Eager]

You can have as many as you like. Think of it like this:

Normal 2 way switch at each end, with 2 wires joining them, yes? (OK, neutral and CPC as well, but they are the same everywhere)/.

In an intermediate switch, all that happens is that the switch crosses the two wires over (an 'X' switch).

Think about it. As many of those as you like, each crossing the wires over again. Operating any of them reverses the wires - and there is light.

[Dave Osborne]

You can have as many intermediates as you want.

Have a look here:

keep adding intermediates between the "end stop" two-way switches.

[george [dicegeorge]]

I'm thinking of putting these switches left/right instead of up/down as up is not always off, and down is not always on, if you see what i mean!

Or is there a convention that all up means off?

[g]

[fred]

Like the diagram :-)

has a good sequence of diagrams at the bottom showing the idea with just one intermediate which the o/p could expand upon on paper.

[John Rumm]

Here are some we drew earlier:

[Owain]

There is when I wire them.

But if you are putting switches where you can't see the light, put in pilot lights.

Owain

[John]

Personally I don't care for the term 3-way Switching.

[John Rumm]

Feel free to change it to something better... "Three way (or more) switching" perhaps?

[Stewith]

A bit pedantic, but may be a bit of knowledge to some....

All wiki articles refer to LIVE and SWITCHED LIVE, but should technically be refered to as Line and SWITCHED LINE.

Both the LINE and NEUTRAL conductors are LIVE.

:)

[Dave Plowman (News)]

He's right. I have six switches on the ground floor hall light circuit.

[Spamlet]

There is a diagram of the internal switch wiring here:

had my brain aching a bit till I saw it.

S

[John Rumm]

Indeed, the content was partly moved from the FAQ and the wording pre-dated even the 16th edition style use of "phase" as the preferred terminology. I might have a tweak later ;-)

[Nightjar]

Multi-point switching?

Colin Bignell

[NT]

The purpose of wiki articles is to inform. Every DIYer understands the terms live & neutral, but only some understand line. In this case nothing would be gained by rewording it to line imho.

NT

[Jim]

you can get with low-energy fluorescent fittings - the capacitance of all those conductors running parallel within the 3-way cables can throw them in a tizz.

[John]

Thanks very much everyone. I now owe my mate a pint as he's the winner of the bet :-)

[John Rumm]

While I agree in principle that the meaning is quite clear as it stands (stood), I can also see an argument for adopting the terminology being used by the IET since it does tend to filter down through other publications and sources of information over time.

[John Rumm]

Its covered here:

add a link...