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#35380 03/10/04 11:42 AM
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Anonymous
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Years ago we would wire 3-ways using two conductor cable only and you would end up with a hot and neut in both 3-ways. One two wire from each 3-way to the light and one two wire between the three ways. This was called a "California" System. However I don't remember the connections. Can anyone provide a diagram or tell me where I can find one. Thanks

#35381 03/10/04 11:54 AM
Joined: Sep 2003
Posts: 650
W
Member
You may also hear this called a 'French three way', 'Carter three way' or an 'illegal three way'. By whichever name you use, it is illegal and dangerous. The system switches the neutral, which is a clear violation of the NEC. Additionally, on one of the 'off' positions the lamp is still 'hot', with both the screw shell and the center pin 'hot' so that there is no voltage between them.

They way that it works is that you use the three way switches _fed_ from the traveller terminals, with the common terminal connected to the lamp. If one three way is switched so that its common is connected to hot, and the other three way is switched so that its common is connected to neutral, then you complete the circuit and the lamp lights. If both switches present neutral to the lamp, then the lamp is off and everything is safe. If both switches present hot to the lamp, then the lamp is off, but everything is energized to line voltage.

Take a look at http://www.geocities.com/gary_wachs/ElectriPuzzles.html for some interesting three way circuits.

-Jon

#35382 03/10/04 01:52 PM
Joined: Nov 2003
Posts: 269
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Member
Also called the "Chicago 3-way too". Whatever you call it its illegal and dangerous. [Linked Image]


John
#35383 03/10/04 05:36 PM
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Anonymous
Unregistered
I tried to post a sketch as a photo but can't figure out how to do that although I have seen it done on other posts...hhmmm.
OK here's the wiring and the neutral is not switched. Took a while to figure this out.
There is a two conductor from each switch to the light and a two wire between the two three ways. The black in the two wire between the switches carries the hot through and ties to a traveller post on each switch. The white in the same wire ties to the common on each switch. The white from each two wire carries the neutral through and both tie to the light.
The black in the same wires both tie to the light and to the other traveler on each three way. Feed this set-up on either end and you end up with a hot and neut on the other end. If this goofy set up doesn't meet code why? Appologies in advance if this has been discussed before.

#35384 03/10/04 06:18 PM
Joined: Oct 2001
Posts: 597
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Thanks, Kent.

Your description answered a question I've had about this scheme since I first heard of it way back. I never could quite visualize it. What I had missed is that the neutral goes off through the light while the hot heads toward the other 3-way. Bringing the neutral to the far 3-way, thus enabling the continuing of the branch circuit is a nice touch.

The polarity at the lampholder is always correct.

The downside, for me is the unbalanced magnetic field created in some switch settings, or when the branch is continued and downstream load is connected. But that is a health issue (and debated, at that), not a NEC issue.

Bottom line, what you described is NEC compliant, IMO.

This is my idea of what you described, KentVW:


[Linked Image]

ElectricAL

[This message has been edited by Webmaster (edited 03-10-2004).]


Al Hildenbrand
#35385 03/10/04 07:57 PM
Joined: Oct 2003
Posts: 289
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the circuit #3 is known as the "american alternating circuit" here. it's prohibited because the fixture can be hot when the light is off...

#35386 03/10/04 08:36 PM
Joined: Sep 2003
Posts: 650
W
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ElectricAL points out the problem with this circuit. Depending upon switch setting or downstream load, your current flows in a large loop, going (in the diagram) from 'switch left' to 'switch right', then 'up' to the lamp, then down to 'switch left'. I believe that this violates 300.3(B), because all the conductors for the circuit are not present in the same cable.

-Jon

#35387 03/10/04 09:02 PM
Joined: Oct 2000
Posts: 4,035
Likes: 1
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:andy,

In this case the conductor that's always in contact with the fixture is the grounded one. There is a another 3-way arrangement that you are probably thinking of.

Bill

(psst; nice picture Al -- [Linked Image] )

[This message has been edited by Bill Addiss (edited 03-10-2004).]


Bill
#35388 03/10/04 09:47 PM
Joined: Mar 2002
Posts: 179
D
Member
I do some work for a builder who also sell mod. homes.The factory wires the fixtures 'hot'at top of basement stairs and bottom of attic stairs,with 3-wire to switch,and 3-wire drops for site installed 3-way.I've been changing them to 'hot at switch' but that's a pain,and time eater;I'd love to site code section to builder to feed-back to modular mfr. to end this.What is it ?

#35389 03/10/04 09:58 PM
Joined: Oct 2001
Posts: 597
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Member
Jon,

I think 300.3(B)(3) provides the exception that results in the setup in the diagram that I drew to be NEC compliant. The common installation would be in a dwelling wired with NM-B.

Al


Al Hildenbrand
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