double-pole or 4-way switch ?

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ronaldrc said:
A fourway light switch is a double pole double throw with just 4 terminals.

click here to see
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True.

Once I built a rack space of DPDT relays to operate as four-way switches.

The coils were controlled by two-wire switch loops. Any switch could be opened or closed, and would actuate its "four-way" relay set, and either turn the final load on or off.

The benefit was two-wire rather than four-wire loops.
 
So both travlers are opened at one time. I thought a 4 way switch opened one travler and closed the other and vice versa...

And a double pole opens both simeltaneously.
 
Go get a 4 way and ohm it out and see first hand. DP switch have on/off written on them so obviously it will disconnect any current flowing when the switch is "off". There is no "off" position on a 4 way.
 
Dennis Alwon said:
Go get a 4 way and ohm it out and see first hand. DP switch have on/off written on them so obviously it will disconnect any current flowing when the switch is "off". There is no "off" position on a 4 way.
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That's the reason I'm asking. I thought I had a 4 way but it is opening both travlers at once.
 
I'm not sure which is which, but DPs should have all 4 terminals the same color, while 4-ways have two brass and two black.
 
If you look at it this way,,,,,,,,,,, A 4-way is equivalent electrically to two 3-ways in one package and is a DPDT,with internal jumpering that is factory installed.

I started to write a explanation of metering but got all out of sync with myself so how about a picture.
 
greeny said:
Nice drawing, however, there's a jumper missing from the outer travellers.
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I don't think so, sketch a 3-way on each side,hot to one 3-way and switch leg to other 3-way,then of course the light and neutral connected to the light.

dick
 
Buck Parrish said:
So both travlers are opened at one time. I thought a 4 way switch opened one travler and closed the other and vice versa...

And a double pole opens both simeltaneously.
Click to expand...


Call each internal SPDT switch#1 & switch#2,,,,,,,,,It does when you measure in and out on each individual switch, in one position it will read closed,toggle the switch and measure again they will read open but this time the internal busing or jumper will cause the reading to read closed from switch #1 input to switch #2 output but never from switch#2 input to switch #1 output.

see my sketch above and number the individual SPDT switches

dick
 
dicklaxt said:
I don't think so, sketch a 3-way on each side,hot to one 3-way and switch leg to other 3-way,then of course the light and neutral connected to the light.

dick
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I agree with greeny. One of the poles on the bottom 3-way is not connected to anything.
 
Here is a diagram of a 4 way switch (SW3)

142029595_d43d9959af.jpg


So you could use a DPDT switch with a pair of jumpers to replicate a 4 way switch.

2.jpg


I doubt, however, there is anything to be gained as I'll bet the DPDT switches are way more expensive than a 4 way, plus consider the next person in the box.
 
dicklaxt said:
If you look at it this way,,,,,,,,,,, A 4-way is equivalent electrically to two 3-ways in one package and is a DPDT,with internal jumpering that is factory installed.

I started to write a explanation of metering but got all out of sync with myself so how about a picture.
Click to expand...


So your saying when moved the line on the bottom with dashes will move up and contact a travler. How ever that pole would become open. While the other pole moves up and becomes shut. Right?


As far a a double pole double throw. The ones I have used are off in the middle. And on in either top or bottom.
While a double pole is just up on and down off. (both poles)
 
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