3-way switches -- old house wiring

[Nate Nagel]

Yup, do that...

there are other options to the "normal" setup but they are rare.

What I'm expecting that you'll find is that since this is an older house, the electrician will have run the hot wire straight to the light fixture location, and from the same box run a 14/3 to each of the

3-ways. Back in the very old days electricity was thought of as primarily a lighting utility and installations reflected that; a floor was typically wired with the hot wires going to the ceiling boxes and switch legs dropped to the wall switches from there. Receps were also dropped from the ceiling light boxes. Wire fill would be unacceptably high today were this a new installation.

I know what I said above sounds crazy, but that is exactly what I found in a house built in the late 40's that I had to do some troubleshooting on after a PO had a "handy friend" replace all the devices and none of the 3-ways worked.

If you do find multiple hot wires with all the switches disconnected, stop there and ask for advice as you may be dealing with something like a California 3-way or if you're really unlucky a Carter circuit.

If your house is newer than 1930ish and/or you can determine that your wiring is NOT K&T but actual cables (can you see the sheath of the cables inside the boxes? I've lived in several houses that had cloth covered wiring but they were a sort of ungrounded proto-Romex but with cloth over rubber insulation on the wires and a cloth sheath over the whole cable) you should not run into the Carter circuit which is good as it would be bad news if you did. I'd be tempted to treat the discovery of one as a sign that it is time to rewire, as it has been prohibited for ages as in half the switch positions it allows the shell of the socket to be energized, making removing a broken light bulb rather dangerous.

nate

[krw]

I "paint" white wires that are repurposed as hots, with a red Sharpie. I keep one in my "electrical" toolbox. I don't know if it's kosher but it works.

[william-bowman]

My situation is a little trickier. When taking off all 6 wires, there's a hot wire at each switch. As I understand it, when the power source is betw een the switches, only one can be connected to the common. The way it's wir ed now, one switch must remain in the "on" then controlled from the second switch.

Without colored wires, the only ones I can identify are the hot wires.

Any advice?

[Micky]

Wired now? I thought you had disconnected the wires.

First, make a drawing. Don't expect to remember what you've seen.

Turn off the power and measure the voltage at the hot wires to make sure you turned off the right circuit.

Then measure the resistance to ground or neutral of the other wires. The ones that go through the light bulb to neutral should have non-infinite resistance. Do this with real lightbulbs in the circuit. I'm not sure what the resistance of other bulbs is.

Mark down the resistance on your drawing.

The ones with infinite resistance are probably just travelers, wires that went to the other switch, and which are disconnected now.

Get the switches, and try to figure out from the way the wires are bent, which wires went to which screws, and try to figure out with a meter, which screw is common and which wires are supposed to be the travelers. With 6 wires, you should have made a drawing before you disconnected things .

Look online for various ways to wire a 3-way switch. There are 4 or

1. Use your meter to help determine which method is yours.

[Stormin Mormon]

Yellow vinyl tape and magic marker allows you to label the wires before removing. So you know where they go. Wrap the tape around the wire and back to itself, making a "tape flag".

Eat light meals when driving on long trips, as over eating makes you sleepy.

Treat everyone with kindness, and manners. Even the burglar who is in your house in the wee hours needs to be treated kindly before you shoot his ass off with a twelve gage and give his carcass to the dog.

Fill the fuel tank of your car before the gage gets to half tank, and you'll be less likely to run out of gas in a bad spot.

Wash your hands every time, after using the toilet. Helps cut down on spread of disease. Use a paper towel to open the public restroom door, so you don't get the disease the last guy had. (Last guy didn't wash his hands.)

Use salt lightly on baked foods such as chicken to bring out the flavor.

Girls like flowers, which are cheaper than divorces.

[Stormin Mormon]

With both switches removed, isn't the bulb connected to nothing on both ends?

[Ken]

In addition to what you said, the above link might be helpful to William.

[Micky]

Maybe with one or two of the ways it can be wired. I can't remember. But certainly with some ways it's still connected to neutral.

[Micky]

It's very helpful to me, that's for sure.

This subpage

is just the sort of page I had in mind. And it enables me to answer the question Chris asked. Take a look and you'll see that one of the six wires always has continuity with the neutral, if a real lighbulb, not burned out, is in its socket. Assuming the neutral has continuity with the ground and that there's a ground wire in the box, that's one place to test with.

And it also reminds me of added instructions for the OP. Because I need a drawing to think with. Is this normal, below normal or above normal? Is it a clever way to save brain power by letting the drawing do some of the thinking? Or would a smart person have all this in his head without any help? I really don't know the answer to these questions. I only have myself to compare with, and I always match.

Keep the power off. (Always check with a voltmeter to make sure the power is off. Sometimes there are two circuits in the same box, even though I think this is not allowed, so one coudl be off and the other on.)

Once you find the wire that has low resistance, under a couple 100 ohms, or a couple thousand if you can't find lower) to neutral, call it N, temporarily connect each of the other two wires in the same box to N. Then go to the other switch box, and check those three wires for neutral (Well, those two probably, because you already found that when the fuse or breaker is on, one of the wires is hot**. But if not, then 3.) The wire that connects to neutral is one of the travelers.

Do the same thing with the other wire at the box1 where N is. Now at box2, you've identified both travelers, at both boxes. Reconnect the switches accordingly.

**You claimed each box had hot wire. That's not possible if you had really disconnected all 6 wires. But if you didn't disconnect all of of them that's fine with me. Post back if you want instructions for when only one switch is disconnected, or only one or two wires of one switch. Let us know exactly what is connected, what isn't, and what the voltages and resistances are. It's unlikely both switches are broken but quite likely that one is.

[Don Y]

If you have a choice between buying a new car and getting married, buy a red one.

[Stormin Mormon]

I once owned a red pickup. Sure felt manly.

[Micky]

I had a girlfriend with a red mustang convertible. Unfortunately, she didn't have it when I knew her in NYC.

We went out once and she told me she wouldnt' go out with anymore because I was too young. I added a year to my age and told her I was

26, thinking that would settle it. She still said I was too young.

In one of my few macho moments, I said, "Well, I'll ask you out again and you can decide then whether you want to go out with me. " And I did and she did.

Found out later she was 14 years older than I was, 25 and 39.