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first-home · Aug 8, 2012, 04:32 AM

Hi guys, I'm trying to repair my three-way switch that wasn't working properly. The light would only come on if both switches were turned on, making it an "and" circuit instead of an "or".

I pulled the switches out and removed the incoming power from the fuse box. I found that the neutral wire is carrying 115V and the black is 0V. The circuit was "working" and my breaker has never tripped. Did someone just swap the neutral and hot wire at the box by mistake? I've tried a few wiring configurations on the switches and nothing worked properly. I don't know of another explanation?

hkstroud · Aug 8, 2012, 05:48 AM

A neutral will show voltage to ground if there is anything on that circuit that is on and there is a break in the neutral line.
A neutral is not connected to a switch. Because the wire is white does not mean it is a neutral.
Three way switches do not have an on and an off position. They are either in the same position (electrically) or they are not. The two switches in the same position amounts to on, in different positions amounts to off.

Better tell us the whole story.

first-home · Aug 8, 2012, 06:07 AM

Okay so right now I've disconnected the switches completely, but what I meant by the three-way switches not working properly was that they both had to be in the "on" position(I do get this isn't an on-off switch, but they both had to be "up").

I can't see anything else on the circuit, I have 14/2 wire coming into my light switch(I believe from the fuse panel), and with everything disconnected the white wire has 120V and the black wire has nothing.

Does that make sense?

hkstroud · Aug 8, 2012, 07:20 AM

There are five different ways to wire a set of three way switches.

Describe the wires in each box. Is this something that just happened or was work done on the wiring.

first-home · Aug 8, 2012, 07:28 AM

When I moved into the house the switches were wired so that the both had to be in the same position ("on") for the light to work.

So I have one switch which has the following;
-14/2 (I believe from fuse box)
-14/2 (going to the light)
-14/3 (going to the second switch)

Second switch only has a 14/3 coming from the first switch.

The supplied power has 120V on the white wire, and 0V on the black.

hkstroud · Aug 8, 2012, 08:25 AM

Still a couple of possibilities.

One possibility is that one 2-wire cable is bring power to the first switch box and the other taking the switched power to the ceiling light, just as you have surmised.

The other possibility is that one 2-wire cable is bring power to the switch box and the other 2-wire cable is simply taking power some where else. In other words that cable is simply passing through the box.
The 3-wire cable in the first switch box would then be coming from the ceiling box. The white would be bring power from the ceiling. The black and red (the travelers) would then be connected (in the ceiling box) to the travelers (probably white and red) of the 3-wire cable going to the other 3-way switch. The black in the 3-wire cable at the second 3-way switch would return switched power to the light fixture itself.

If that is the situation there will be something, probably an outlet, that doesn't work when you have everything in the first switch box disconnected.

First disconnect all wires in the first switch box, cap all wires with wire nut. Restore power and see if there is anything other than the light that does not work.

Connect the blacks and whites of the 2-wire cables together and restore power. If the light is on, things should be as you have imagined. If the light is not on, then things are the second possibility.

Or

Connect the white of the 3-wire cable, which I presume is the white with voltage, to the common of the first 3-way switch. Then check for voltage to ground between the wires in the second switch. Flip the switch and check again. The two wire that have voltage are the travelers (should be red and white). The remaining wire with out voltage (should be black) would be the switched leg to the light.

Before doing this, check the switch. I suspect that you have a defective switch. You should have continuity between the common and one traveler screw with the switch in one position and continuity between the common and the other traveler screw in the other position.

Another approach would be to examine and describe the wires in the ceiling box.

first-home · Aug 8, 2012, 08:42 AM

Awesome! I'll check and see if anything else looses power while everything is disconnected.

In the second option, it is the 14/2 that has the power, not the three wire. I'll also confirm the switches are working correctly with nothing attached.

The fixture looks like a pain to open but worst off I will open it up and have a look. Ill let you guys know tomorrow what I find. Thanks for all the help!

hkstroud · Aug 8, 2012, 10:00 AM

In checking for voltage between the white and ground, if the blacks of the 2-wire cables are connected and the whites are not, the power cable will show 0 volts, the other will show voltage. This will be true if the other cable goes to the light. It will also be true if the other cable goes somewhere else and there is something plugged in and turned on.

smearcase · Aug 8, 2012, 11:44 AM

HK
I believe that there are actually at least 36 ways to hook up a set of 3 way switches. One switch switch can be hooked up 6 different ways (3x2x1), and for each of those 6 ways the other switch can also be hooked up 6 different ways, that is if someone is just attempting it by trial and error. Four of the 36 trials will work. Not good odds for guessing. Sound right?

first-home · Aug 8, 2012, 12:09 PM

I'm going to go out on a limb here and say that HK means there are about five different ways to
CORRECTLY wire a set of three way switches. I found a site with diagrams for eight different options (Installing A 3-way Switch With Wiring Diagrams - The Home Improvement Web Directory), but HK's response was about a hundred times more helpful than your likely sarcastic statement... thanks for showing up though.

hkstroud · Aug 8, 2012, 12:11 PM

When I say 5 ways I'm speaking electrically.

If you want to say that connecting traveler screw #1 on switch #1 to traveler screw #1 on switch #2 and traveler screw #2 on switch #1 to traveler screw #2 on switch #2 is one way, and that connecting traveler screw #1 on switch #1 to traveler screw #2 on switch #2 is another way, then the number of ways certainly goes up.
If your travelers are going through the ceiling and you are using red and white as your travelers, then red could be connected to red, and white connected to white, or you could connect red to white and white to red and traveler #1 would become traveler #2. Then of course you could turn one switch upside down and traveler #2 would revert back to traveler #1.

By now the electrons have gotten tired and gone home in disgust.

hkstroud · Aug 8, 2012, 12:17 PM

your likely sarcastic statement

I'm sure that that was said in humor, not sarcasm

tkrussell · Aug 8, 2012, 12:19 PM

This is priceless...

Originally Posted by hkstroud

By now the electrons have gotten tired and gone home in disgust.

smearcase · Aug 8, 2012, 12:21 PM

My only intent was to show the futility of a person just trying to hook up 3 way switches by trying all the possible hookups one at a time.

hkstroud · Aug 8, 2012, 01:04 PM

futility of a person just trying to hook up 3 way switches by trying all the possible hookups one at a time

Agree. You have to be smarter than the equipment you are workng with.

first-home · Aug 8, 2012, 03:01 PM

Okay this is making no sense what so ever to me! My power coming into my junction box on the white wire is 118V to ground, the black has 13V to ground, between the two is 62V. What?

My light is not supplied power, it has two wires going to it. The switches are out of the picture right now. If I only connect the white wire, I give BOTH white and black at the light 120V.

first-home · Aug 8, 2012, 03:04 PM

Originally Posted by first-home

Okay this is making no sense what so ever to me! My power coming into my junction box on the white wire is 118V to ground, the black has 13V to ground, between the two is 62V. Wtf?

My light is not supplied power, it has two wires going to it. The switches are out of the picture right now. If I only connect the white wire, I give BOTH white and black at the light 120V.

Just wanted to ad that whether the black wires at the junction are connected or not it makes no difference.

hkstroud · Aug 8, 2012, 03:28 PM

Not to me either, we are going to have to dig a little deeper.

To be clear, you only have a single 2-wire cable into the ceiling box.

When you test for voltage on the white are you doing so with the black wires of the 2-wire cable disconnected.
We are getting desperate here. Do a voltage check to ground (black and white, both cables) with the breaker off.

If you are comfortable opening you circuit panel, remove the cover, look to see if the breaker controlling this circuit is wired using a 3-wire cable. If so see what breaker the other wire goes to.

hkstroud · Aug 8, 2012, 03:32 PM

If I only connect the white wire, I give BOTH white and black at the light 120V

Does that mean you show 120v black and white (light cable) to ground but light does not burn?

first-home · Aug 8, 2012, 07:53 PM

Yes the light does only have two wires (14/2) the power supply also has two wires, then there is 14/3 between the two switches, they are disconnected completely right now, for testing purposes.

I am testing with ALL wires disconnected, and measuring VAC to copper ground strap.

I popped off the breaker cover and it looks like there is only a two wire, black is on power and white is on the ground bus with all the others.