4 Way Light Circuit.

[EasT]

This is purely idle curiosity. Some 10 years ago I put an extra light switch at the bottom of the stairs for my daughter and converted her landing light to two-way. Not too difficult.

In my hall the light is operated by four different switches. I have no ideas how complicated a 4 way circuit is. I would have no idea where to start.

Is it as difficult as I suspect ??

 

[mnmwill]

2 way switch - intermediate - intermediate - 2 way.

Move the common to L2 @ the first switch then taking 3 core cable -

Grey to common, brown to L1, Black to L2.

@ intermediate, common into choc block / wago, brown to L1 @ top, Black to L2 @ top

@ 2nd intermediate see above

@ final switch grey to common, brown to L1, black to L2

Colours are not definitve, use whichever ones you like for common, L1, L2.

Think thats it anyways!

 

[basset]

Is this the correct way to wire a 4 way switch?

 

[davesparks]

Is this the correct way to wire a 4 way switch?

View attachment 32897

It is one of the ways of doing it yes, although your colours are a bit squiffy

 

[EasT]

It is one of the ways of doing it yes, although your colours are a bit squiffy

Hi Dave. As the OP I have read the posts on this thread. Prior to posting I had asked the same question of two well qualified and practising electricians who did not know the answer. I failed to thank the respondents and so.

Thanks to All.

Alan

P.S. I am grateful for the help that I have been given on this forum on other aspects.

 

[PRR]

As this was posted for "idle curiosity", I shall not apologize for coming in weeks late.

Google can help. Many of the examples are US-based. However the electrons don't know where they are. The wiring is the same everywhere. Wire colo(u)rs, and how you minimize the number of several-wire cables, may differ.

First though, a story. My 1834 house only had a stair-light switch at the top of the stairs. As the framing was erratic and the "plaster" very fragile, yet mildly historic, I did not want to run cable to the bottom of the stair. I blew $30 for a "wireless 2-way switch". One unit replaced the hard-wired switch. The other was a surface mount box which easily screwed to the wall, no wires. It had a battery. Every few years it went "deaf" and we put another battery in. All told it was the same cost as hard-wire and many hours of ugly work avoided. I think you can get these with 2 or 3 remote units.

You seem to know how a 2-switch loop works. Power to one SPDT switch. This puts power on one or the other of two "traveler wires". These go to another SPDT switch which takes power (or not) off one or the other traveler. In US parlance these SPDT switches are called "3-way" (perhaps should be 3 wire).

For 3 switches the middle switch is a DPDT which swaps the travelers. We call these "4-way" switches. You can make one with a 6-screw DPDT switch and a jumper. But for this purpose you buy it pre-made with 4 screws. Once you get this level of sophistication, you can extend it to infinity. A 10-landing stair takes two 3-way and eight 4-way switches.

Good introduction albeit with US color conventions:

http://users.wfu.edu/matthews/courses/p230/switches.html
http://users.wfu.edu/matthews/courses/p230/switches/SwitchesTut.html
http://users.wfu.edu/matthews/courses/p230/switches/multilightsmultiswitches.html

Looks easy on paper. Maddening in the house. Lots of running up and down stairs to check things. Also:

The two travelers do the work of one wire in simple switching. This means that normal 3-wire cable (hot, neutral, earth) won't do the whole job. I can buy 4-wire cable but it is beastly more expensive and usually offered in short rolls.

That website shows one light. In a stair you want a light at each landing. This needs 5 wires, which is not a standard cable. At this point it makes a lot of sense to wire all the lights on one cable, all the switches on a separate cable.

Cable colors assume one wire will be Neutral, with its designated color. These several-way switching plans often have no neutral in a run. US NEC requires a white wire to be Neutral, *except* when running a switch-leg in cable.

I "have" to get crayons and work it out on paper. Wire-up to the plan. If problems found, correct the drawing. Then post or tuck it near the circuit for future reference. (The next electrician; or me after I forget what I did.) Here's a simple sketch for a 1-story 2-flight stair with door and a light at the middle landing.
https://s25.postimg.org/jbd88m0b3/3_way_600.gif

And even then... I like it so all switches "down" is "OFF". No matter how I work it out, I always have to take out one or two switches and turn them over.