View Full Version : Three way wiring

07-26-2007, 06:49 PM
I came across a home with a detachable garage wired using three way switches, but in the garage their is only two lines coming in.... I'm wondering how this would work with only two lines..........

07-26-2007, 09:21 PM
it is as easy as understanding how a circuit works.
this is the first step in learning circuity

07-27-2007, 06:50 AM
Not really sure of the question. All household 120 volt is electricity is "two lines" meaning 2 wires, white and black, not counting the ground. Let's not talk about 240 or multiwire circuits for now.

You say the garage is wired with three way switches. By that I assume you mean the lights can be turned on and off from switches at 2 differents sides of the garage. This is simply a matter of how the circuit involving those switches and the lights is wired. Bottom line is still this: the light bulb is looking for one "hot" line and one "neutral" line: two lines.

For a circuit diagram of how 3-way switches are connected, and good general information about your home electrical work, the little green book available at all hardware stores is excellent. I believe it is called "Wiring Simplified" or something like that. Really an excellent book if you want to do anything electrical around the house.

07-27-2007, 07:26 AM
In the garage there is conduit from floor with two wire. Two three way switches are use..... house & garage. In a three way switch configuration two traveler wires run between the pairs of traveler screw terminals... With only two wires at garage......... how is this possible?

07-27-2007, 10:02 AM
Maybe I am misunderstanding the question.

I can wire a set of three way switches between two buildings that will turn the lights on and off and at the same time using the same conductors have a receptacle at the remote building that is hot all the time.

Is this what you are talking about?

07-27-2007, 11:16 AM
I know a nuetral has to be considered .......... correct?

07-27-2007, 11:56 AM
i would check to see what leaves the switch box going up to the light, where is it getting it's neutral? use a meter, is it metal conduit? because the neutral could incorrectly be made at the conduit which is not correct, but i've seen alot of hack jobs and nothing would surprise me anymore. but it sounds like something is miswired and if there are only two wires going from the garage to the house but you can switch light from two locations someone incorrectly made a neutral somewhere

07-27-2007, 12:05 PM
Never trt this at home but this might help someone better understand how a circuit works.

07-27-2007, 12:12 PM
I'm sorry...... Guess I should have brought the nuetral up earlier... Its really strange....... Its just to leads coming from an open section of conduit...I have not really tried check this thoroughly...... I know thru the years I've seen some strange setups. My Uncle had a home where if you touched the heat register duct, and the cold or hot faucets at the same time it would light you up,,,, The register ws on the floor directly below the bathroom sink...so you had to make sure you were not barefoot, and positioned correctly........... :-)

07-27-2007, 12:16 PM
Just seen diagram....... Looks like a great possibilty...........

07-27-2007, 12:16 PM
nice picture, it has hazard written all over it, but then again it would work

07-27-2007, 12:20 PM
Gets confusing....... when you read, and note correct ways to do something, and run into stuff such as this you wonder what people were thinking about when they did it..I guess all they had in mine was getting it done......

07-27-2007, 01:12 PM
there is a possibility it is a version of the "california three way" or a "french three way" or even a "Chicago three way".
I have heard various names for these two different wiring configurations, and there are probably more variations of them yet,

more than likely what they did was take a hot wire and wire it to the single side of the 3 way switch and then take the two runner/carriers wires and take them to the other 3 way switch and then to the bulb and then to a local neutral wire on a different circuit if all you can fine is two runner/carrier wires,

and there is another version of the wiring is where basically it feeds from two different locations or circuits on the same phase side, with the bulb in the center. and the three way switches (one each end) are either feeding the bulb two hots or two neutrals, and either way the bulb is off in that instance but once one switch is flipped to the other side it completes the circuit,
(this method was used on yard lights a lot at one time as you could get by with jsut one wire coming to the light post from each building).

It is not a suggested method of wiring a three way switch,

07-27-2007, 01:22 PM
His house also has quite a bit of knob & tube wiring still in use. Especially on the 2nd floor. I suggested running a new line to garage, but burying new cable might not be his thing... Is it possible to run power above ground with a smaller weather head to garage? Looking at a run of 30'? I've seen smaller weatherheads at home depot..

George R
07-27-2007, 02:45 PM
It's also referred to as the Carter system.

There was a discussion of it here


It's a dangerous situation because either the pin or the threaded part of the socket can be hot depending on the position of the switches (even with the light off).

Its been an illegal install since the 1930's.

08-01-2007, 12:24 PM
Regarding the Calif threeway wrirng is there a diagram of this sort of setup?

08-04-2007, 12:44 PM
another discussion on it at another board, and some links and a few illustrations, http://forums.mikeholt.com/showthread.php?t=88390&page=3

carter or at least that is my understanding of the method,


basically it is my understanding that the neutral on the California is picked up at a different location, using two travelers between the two switches, and not returning with the neutral to the power source location,

08-04-2007, 03:01 PM
In that configuration there is only one "traveler" between the switches but it still needs 3 wires between the two locations.