3 Way Switch Not Working Properly


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Old 07-15-18, 10:27 AM
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3 Way Switch Not Working Properly

I have a hallway with a switch at both ends and 1 light fixture. I recently replaced both switches with standard 3-way switches. The old switches were labeled differently so I had to try to transfer the wiring form one to the other the best I could. The wiring is somehow wrong with my new install.

I've looked at how-to videos and they all assume one box has the power feed wires AND traveler wires and the other box has the light fixture wires AND other end of the traveler wires. But in my case, there are ONLY 3 wires in each box. Red, Black, White (and ground). So I can't really tell which is load, line, or traveler like the online diagrams/videos.

In both boxes I connected the black wire to the black screw connection on the 3-way switch.
Then connected the red and white wires to the traveler screws (remaining 2 screws).

This is how the circuit operates;
-If switch #1 is in the on position, switch #2 does nothing in either position.
-If switch #2 is in the on position, switch #1 does nothing in either position.
-If switch #1 is off, switch #2 will operate the light on and off.
-If switch #2 is off, switch #1 will operate the light on and off.
So, one switch MUST be in the off position for the OTHER switch to operate the light.
ONLY one switch at a time works assuming the other is in the off position.

Looking at a typical 3-way switch, with 1 light wiring diagram this scenario seems to mean the power and load are correct, but 1 traveler is not making a connection to the other switch so only 1 traveler is passing power and therefore, 1 switch has to be off for the other to operate. I don't know if this is correct.

Any help with this would be great.
Thanks
 
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Old 07-15-18, 10:31 AM
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Welcome to the forums.

There is no standard for three way wiring. The only standard that has never changed is that there is a dark/black screw on a three way switch that is the common wire. What ever comes off the dark screw goes back on to the dark screw.

I will work with you if you want to ID the wiring. You would need a voltmeter or two lead voltage tester to start.

With three way switches...... 99.9% of the time...... the two traveler wires will be located in the same cable. Look at the three wires at both ends..... can you see two wires going into the same jacket ? If yes.... those are the traveler wires and go on the gold screws. The remaining wire is the common wire.
 
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Old 07-15-18, 06:30 PM
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Thank you for taking the time to respond.
I understand what you say about the travelers being in one wiring jacket and the load/line in another. That is what almost every diagram I could find shows and why I'm confused. In both switch boxes there is only 1 romex wire entering the box with red/black/white/ground. Those are the only wires in either box. Of course, I don't know how things are wired outside of the boxes.

I have a voltmeter and tomorrow I can test each of wires to ground to see which is hot 110V and assume that is my line in. I don't know which switch box has the line in and which has the load from the light fixture.
 
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Old 07-16-18, 10:27 AM
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Three-way switch circuits are absurdly simple. If all you have is a single three-wire (plus equipment ground) cable into each switch box then the power MUST come in at the light fixture or an intermediate box; the intermediate box is unlikely.

By opening up the lamp fixture it should be obvious where each cable is coming from and how the individual wires are connected. Power would come in on a two-conductor cable with the white connected to the white (or silver screw) of the lamp fixture.

What I would do is to re-identify the white wire at each switch by using colored tape or a permanent marker to a color other than white, grey or green. Blue is easy. Then disconnect the wires from the three-wire cables (both of the cables) in the light fixture box and connect the black and the red wires from one cable to the corresponding colors in the other three-wire cable. This will leave a black from the two-wire cable and the two re-identified whites in the two three-wire cables along with the black (or brass screw) in/on the lamp fixture. Connect the black from the power supply cable to one of the re-identified whites and the black from the fixture to the other re-identified white.

At the switches connect the red and black wires to the brass screws (order not important) and the re-identified whites connect to the black screw on each switch.
 
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Old 07-16-18, 01:20 PM
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Wow, thanks for the detailed reply.
It makes sense. I'll get on it.

Thank you again.
 
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Old 07-16-18, 04:11 PM
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I rarely comment on three-way switch issues because they are so simple. Where most people have trouble is they seem to think that the actual wire colors must be in a certain order or that the screw positions on the switches are in a standardized position, they are not and you have to go by screw color rather than position.

If the installation uses conduit and individual conductors instead of cable then I use black wire for the connections to the black screws and use some outlandish color such as pink or yellow for the travelers. Since it makes no difference which traveler screw on one switch connect to the other switch I make them both the same color. Doing it this way makes it easy in that the proper color coding of "hot" and "neutral" wires is maintained and the black will always connect to the black screws of the lamp and power supply conductor. It also makes it obvious what wires are the travelers.

I also think it is helpful for a person to draw out the circuit on a piece of paper. The traveler wires always connect straight through between switches with one switches' black screw being power in and the other switches' black screw being power out to the lamp. Re-identifying the white wires in the three-wire cables goes a long way to reduce confusion as DIYers often think that a white wire must be a neutral which is NOT the case with a three-way switch circuit.
 
 

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