2-way switch?

[blackrose]

I want to put a second switch (inside the boat) into a 12v circuit for a circulation pump which already has a switch at the helm.

 

I was told I need a two-way switch, but I can't get my head around how it would work. If the switch is off at the helm then surely the circuit is broken and it doesn't matter what I do with a switch inside the boat? Or if I left the switch at the helm in the on position then I wouldn't be able to switch the system on from the helm with the switch in the cabin off.

 

I'm obviously missing something here so any advice appreciated.

 

Thanks

Edited September 19, 2012 by blackrose

[Robbo]

Diagram's say it all..

 

 

or

 

Edited September 19, 2012 by Robbo

[Gibbo]

[BEngo]

I want to put a second switch (inside the boat) into a 12v circuit for a circulation pump which already has a switch at the helm.

 

I was told I need a two-way switch, but I can't get my head around how it would work. If the switch is off at the helm then surely the circuit is broken and it doesn't matter what I do with a switch inside the boat? Or if I left the switch at the helm in the on position then I wouldn't be able to switch the system on from the helm with the switch in the cabin off.

 

I'm obviously missing something here so any advice appreciated.

 

Thanks

 

If the existing switch at the helm position is not already a two-way switch you will need to replace that one with a two-way switch and add another two-way switch at the 'new' position so as to achieve the set-up in the diagrams. Should you then want to add a third position you need a thing called an intermediate switch or double pole double throw (DPDT).

 

N

Edited September 19, 2012 by BEngo

[blackrose]

Thanks. The existing switch isn't two-way but I get it now.

Edited September 19, 2012 by blackrose

[ditchcrawler]

Diagram's say it all..

 

 

or

 

Coo I wish they had animated drawings like that in 1963 when I started my apprentaship. I remember one of the questions was how many switching combinations are there for a 2 way and intermediate switched circuit?

[RLWP]

 

We have three switches controlling a single light in our back kitchen

 

Richard

[WotEver]

We have three switches controlling a single light in our back kitchen

 

Richard

That'd be like this then:

[Bob18]

Robbo - that is a brilliant animation - have a greenie

[RLWP]

That'd be like this then:

 

It certainly would - except there is no neon

 

You can continue adding switches almost indefinitely like that

 

Richard

[Gibbo]

We have three switches controlling a single light in our back kitchen

 

You can have as many as you want, but once you get past 4 switches you start to need bigger switches with more contacts.

[nb Innisfree]

My head hurts.

[MoominPapa]

You can have as many as you want, but once you get past 4 switches you start to need bigger switches with more contacts.

Why? Surely you can have as many of the intemediate changeover switches as you like? Too large circuit resistance from all the contacts is series?

 

MP.

[Guest]

Why? Surely you can have as many of the intemediate changeover switches as you like? Too large circuit resistance from all the contacts is series?

 

MP.

Best to use a relay when many switches present.

[Gibbo]

Why? Surely you can have as many of the intemediate changeover switches as you like? Too large circuit resistance from all the contacts is series?

 

MP.

 

Because I meant to type 2 instead of 4.

 

With 2 switches you only need a SPDT at each end. Once you get to three or more you need DPDT switches in the middle.