Replaced 3-way switch, now it works only in one position

imjayhawkJuly 26, 2010

This morning, I replaced two 3-way switches that control a hallway ceiling light, and now it works on only one position. Both switches had one black wire connected to the common and then red and white connected to the travelers. When I replaced, I didn't care much about the travelers as I read in several DIY sites that it didn't matter. Unfortunately that doesn't look like the case. Now the switch works only when one of the switches is on the OFF position, but not when its on ON position. After consulting some wiring diagrams, I can't make sense of the way this circuit is wired nor why it is not working. One three way switch is by itself and the other is in a 4 gang box.

I'm calling the 3-way switch at the 4 gang box Switch1. Its wired with NM14-2 and NM14-3 wires. The Red and White from NM14-3 wire is connected to the 'travelers' and the black is connected to the hot wire for all other switches in the box. The NM14-2 cable's black is connected to the 'common' of the switch, and the white wire is connected to the neutral to complete the circuit for all switches in the box(I think!). Switch2 is by itself and has a NM14-3 whose black is connected to its Common and the red and white to its travelers. I have not looked at how the light is wired.

Here are my testing results (continuity tested using a multi-meter):

SW1 SW2 Continuity@SW1 Continuity@SW2 Light

On Off Redwire Whitewire Off

Off Off Whitewire Whitewire On

Off On Both Redwire Off

On Off Both Redwire Off

If you understand this circuit, can you help me fix this? I'd really appreciate.

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hendricus

1. Black from source (circuit breaker) to common of one switch. Black from light to common of other switch. Travelers to other two positions of switch.

If switches are wired the same the light will be off if both are up or down. The light will be on if one is up and the other is down.

There is no off or on position on a 3-way switch.

Look for the word common stamped on the switch, maufacturers put them in different positions. If you went by the old switches they could be wired wrong.

If you made no changes to the light don't mess with it now. The whole problem is with the switches.

    Bookmark   July 26, 2010 at 8:06AM
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brickeyee

"Look for the word common stamped on the switch, maufacturers put them in different positions. If you went by the old switches they could be wired wrong."

I do not htink I have seen a 3-way marked with "common" in years.

The common is usually a different color screw than the travelers.

Black is often used with the travelers remaining brass colored.

The position of the screws has NOT been the same over the years, so if you failed to identify the common on the old switch all bets are off.

What you describe is usually caused by the common and a traveler being swapped.

    Bookmark   July 26, 2010 at 8:46AM
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Billl

The common is swapped with the traveler on the down side. Swap those wires on both switches.

The basic setup should be that the power comes in to the common on the first switch. 2 travelers go to the second switch. The common on the second switch goes to the light.

The way a 3-way switch works is that there is no On and Off. When the switch is Up, it connects the common and the top traveler. When the switch is Down, it connects the common and the bottom traveler.

So, if power is going to the first common and the first switch is Up, then power goes down the top traveler until it gets to switch 2. If that switch is Up as well, then power goes from the Up traveler to the switch 2 common and on to the light. If switch 2 is down, power doesn't get to the light.

    Bookmark   July 26, 2010 at 9:09AM
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imjayhawk

Thank you for the advice.

Both the switches have the common marked. Even in the one that I replaced, they had the common marked (the screw is colored black). The travelers are not marked, but the screw is brass.

It is for sure that the blacks on both old Switch1 and Switch2 were connected to the common. It is the red and the white that I'm not too sure about which traveler screw it was connected too. Since I read that it didn't matter, I didn't take care to note that down when I took it off.

One thing I don't understand is how the first switch is wired. From the above posts, I gather that the common on the first switch has to be the hot wire so in my case the black on the NM14-2 is hot. If that is the case, what is the black on the other NM14-3 is connected to? The red and white of this NM14-3 is connected to the travelers on Switch1.

    Bookmark   July 26, 2010 at 10:20AM
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normel

If one switch has only a 14/3 going to it, at that switch connect the black to the common, the red and white to the traveler screws. At the other switch, connect the black from the 14/3 to the black going to the light and the red and white to the traveler screws. Connect the constant hot black to the common screw of this switch.

    Bookmark   July 26, 2010 at 11:54AM
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imjayhawk

After doing voltage tests, I found that the hot wire on Switch2 was hot. The red-white travelers then went to switch1. From switch1, the black common went to the light. Whoever said it didn't matter which traveler the red/white traveler wires are connected ARE WRONG. It does. Learned it the hard way.

    Bookmark   July 26, 2010 at 2:21PM
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hendricus

I do not htink I have seen a 3-way marked with "common" in years.

Two decora 3-way switches bought at Menards and installed in June 2010, I have to use a magnifying glass but they were marked.

    Bookmark   July 26, 2010 at 2:30PM
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Billl

"Whoever said it didn't matter which traveler the red/white traveler wires are connected ARE WRONG"

No. It sounds like you don't really understand the circuit. If you cross Traveler 1 and Traveler 2 between switches, all it changes is whether Up-Up means "On" or Up-Down means "On". If you switch the "travelers" and the light no longer works, then you misidentified the travelers or the common pole.

    Bookmark   July 26, 2010 at 3:03PM
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imjayhawk

Billl:

I see your point. But in my case, I had to put the travelers opposite of each other between the switches. I struggled on this for a long time until I used the multi-meter to test the hot. First I found the black wire that is connected to switch2 is the hot coming in, and not the black on switch1 as I had previously thought. The two red and white travelers from Switch2 connect to the Switch1's travelers. The black wire that connects to switch1 is then connected to the light.

Breaker ----> Switch2 -------> Switch1 -----------> Light

All this time, the black wires have always been connected to the switches' common. Since Switch2 has the hot coming in, at anytime either Red or White is hot going out of Switch2. When I had the white and red travelers go in the same traveler connections in the switch, it was only lighting the bulb in only one position. I then connected the white and the red just the opposite of Switch2 on Switch1 and it started working. But now that I think of it, it doesn't make sense. Oh well!!

Thanks all for your input.

    Bookmark   July 26, 2010 at 5:31PM
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