Is my 3-way switch economical ?

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Re: Is my 3-way switch economical ?

George, make several copies of the diagram and use colored pencils to indicate the various switch positions. This helps me decipher thermostat diagrams which are convoluted.

John, never had to use a four way, but it figures that they would come with only four terminals.
 
Re: Is my 3-way switch economical ?

:D George, would you like hash browns with that?
 
Re: Is my 3-way switch economical ?

Is the 4 way switch available with 4 terminals, or do you have to use a DPDT with 6 terminals?
Click to expand...
Rattus,

that's the route I took when I first figured the thing out. I didn't know there was a switch preconfigured for it. :)
 
Re: Is my 3-way switch economical ?

For those who know Boolean algebra, you can make a truth table which covers the 16 combinations of switch positions and come up with a logic equation for the function. Exactly half of the combinations will turn on the lights.

The equation for the standard 2-switch configutation is known as an exlusive NOR.

This does save one wire over the conventional method which I would have used.

And, if you arrange the binary codes in a sequence known as the "Gray Code", each step in the code toggles the lights on

[ December 23, 2004, 11:57 AM: Message edited by: rattus ]
 
Re: Is my 3-way switch economical ?

The Truth Table :)

Edit: That's also the way I went about it. :cool:

[ December 23, 2004, 11:37 AM: Message edited by: physis ]
 
Re: Is my 3-way switch economical ?

Just for fun, let's label the switches as A, B, C, D. Then depending on how you define ON, the Boolean expression for continuity to the lamps is:

(AB + A'B')(CD' + C'D) + (AB' + A'B)(CD + C'D')

Now, who wants to expand it and prove me wrong?
 
Re: Is my 3-way switch economical ?

Okay, now I didn't clutter up your guys' infinite math bit with switching, why you gotta come along and turn fun switching into math? :D
 
Re: Is my 3-way switch economical ?

George, my first logic course was in relay logic. It is as much fun as wiring up fancy things. Besides, you don't get calluses and burned fingers.
 
Re: Is my 3-way switch economical ?

"Placing the feed in one switch and the switch leg in the other switch results in both boxes needing to be a minimum of 16 in?. In my opinion, this leads to less thought during installation and being able to work with one size of box. Less labor, more economy."

Or how about this: Feed into 1st switch, 14/3 to fixture, then back to second switch. Hot goes to common on 1st switch, neutral goes to fixture on white wire of 14/3, black & red are nutted at fixture as travellers. Travellers leave fixture to terminate on second switch, white connects to fixture and to 2nd switch common, bringing the power to the fixture. Less wire, less box fill, less time.
 
Re: Is my 3-way switch economical ?

Any of the half-dozen or more possible cable layouts that could be used for three-way switches could be the most economical, in any given building.
It would depend on the type of construction, whether there is an attic, basement, or other access for wiring installation.

white connects to fixture and to 2nd switch common, bringing the power to the fixture.
Click to expand...
Most codes require the "switch leg" conductor supplying the fixture to be "other than white." (sketch "C" below)

Ed

3way5.gif
 
Re: Is my 3-way switch economical ?

That's weird--it's like your B & C drawings were generated by two different minds.

If a person were to prefer Black as common, red and white as travellers for a dead-end threeway (as I do,) why would they suddenly want a red common for the "travellers high" threeway? You've essentially got a dead-end for the switchleg-dictating side. Sounds like a recipe for a mistie, IMO.

Very clear picture, though, Ed. Got any more? :)
 
Re: Is my 3-way switch economical ?

There's a house I've done that has a lamm running through the kitchen, splitting the cans...

Buffet.jpg


[ December 24, 2004, 09:20 PM: Message edited by: georgestolz ]
 
Re: Is my 3-way switch economical ?

Then there's the "Oh crap, I forgot this was supposed to be a four-way" four-way...
Mohel.jpg


[ December 24, 2004, 09:19 PM: Message edited by: georgestolz ]
 
Re: Is my 3-way switch economical ?

And last but not least, there was that badly framed garage that spawned this one...
GarageCalibene.jpg


[ December 24, 2004, 09:16 PM: Message edited by: georgestolz ]
 
Re: Is my 3-way switch economical ?

But you would be at your limit of 32 cu. in. for box fill in the #2 two-gain and you could not pick up that receptacle down below it with out first running the 14/2 to it first then to the #2 two gain.
:D
 
Re: Is my 3-way switch economical ?

Originally posted by hurk27:
But you would be at your limit of 32 cu. in. for box fill in the #2 two-gain and you could not pick up that receptacle down below it with out first running the 14/2 to it first then to the #2 two gain.
:D
Click to expand...
Have you been into the egg nog Wayne? I assume you mean "Two Gang" when referring to double boxes. Just for info there are two gang boxes with more than 32 cu in capacity.
 
Re: Is my 3-way switch economical ?

I think we're in agreement that that sucker would be a hard sell against box fill! :)

Box#2, 14 AWG garage cali = 11 conductors, 22 inches, plus 8 inches in devices, plus 2 grounding = 32 in, which slides in a 1/2 inch low on a fiberglass Allied box.

[ December 24, 2004, 08:46 AM: Message edited by: georgestolz ]
 
Re: Is my 3-way switch economical ?

You know what Rattus, I don't remember how to do it. :(

I'm gonna have to go find a quick refresher on the net. When I get to it.

But George, this actually has a potential to be useful for something.
 
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