3 way switch - 2 wires between

[Dennis Alwon]

I think the misunderstanding stems from the OP's install being called a Calif. 3 way. It is not, IMO.

 

[480sparky]

I think the misunderstanding stems from the OP's install being called a Calif. 3 way. It is not, IMO.

This is what I call a Cali3Way.

 

[roger]

This is what I call a Cali3Way.

​

And as already stated, that is not what is being discussed.

Even though the Chicago three way is illegal it does not have EMF issues along the circuit conductors which the legal two wire NM method does.


Roger

 

[trex]

What art in the 08 code makes this legal with nm cable

 

[macmikeman]

If you have a good volt tic you can have some fun with that two wire traveller setup. What I have found over the years is sometimes it will cause the volt tic to light up and sing when placed near to non conductive surfaces such as drywall or doors in the same dwelling. Do not ask me why, I am not close to knowledgeable enough to explain how a volt tic tester gets charged up this way. I have heard that they detect capacitive charge not inductive so the inductive field may or may not have anything to do with it. By the way, I concur- metal conduit system- violation. NM cable- no violation but I just use three wire cable anyhow.

 

[roger]

What art in the 08 code makes this legal with nm cable

The better way to look at it is that there is no article that makes it illegal for NM wiring methods.

Roger

 

[One-eyed Jack]

Looked at an existing home (brother-in-laws) and found that the 3 way switch in the dining room only has 2-wire running from 3-way to 3-way. Have not found where the switched leg is being picked up for the receptacles in the room. I have always seen 3-wire to carry current over the "travelers" between switches, then to the fixture on the common leg. Anyone have any thoughts on how this was installed. Never seen before and have not figured out yet. Gong back tonight to open up more boxes. All this work to install an overhead light for the dining room.

Have you gotten a satisfactory answer to your question?:grin:

 

[Dennis Alwon]

What art in the 08 code makes this legal with nm cable

Try article 300.3(B)(3)

 

[One-eyed Jack]

This is what I call a Cali3Way.

At least this is better than switching polarity on the duplex.

 

[nogard1126]

Wouldn't this be a violation because half the time the bulb socket would be reverse polarity. In the even someone decided to change the light bulb when it was on, and the normal neutral was hot the person more easily come in contact with the threaded hub portion of the socket which would normally be a neutral. Just a thought.

 

[Dennis Alwon]

Wouldn't this be a violation because half the time the bulb socket would be reverse polarity. In the even someone decided to change the light bulb when it was on, and the normal neutral was hot the person more easily come in contact with the threaded hub portion of the socket which would normally be a neutral. Just a thought.

Yes, it would be and it is a violation.

 

[benaround]

I have only seen knob and tube three ways wired like that picture.

 

[gndrod]

Hash

Hash

The better way to look at it is that there is no article that makes it illegal for NM wiring methods.

Roger

Absolutely correct....but a return loop from the Two-wire traveler in certain unshielded raceway conditions can cause disruptive line approximite noise in computers, communications, sound equipment, etc. Non-canceling circuit re:[300.3(B)] & [300.20(A)] Some day the NFPA will expand on NM wiring mistakes. rbj