Two-way and intermediate switches

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

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.

You can have as many intermediates as you want.

Have a look here:

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?

Like the diagram :-)

Here are some we drew earlier:

There is when I wire them.

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

Owain

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

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

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.

:)

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

There is a diagram of the internal switch wiring here:

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 ;-)

Multi-point switching?

Colin Bignell

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

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.

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

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.

Its covered here: