Old 3-way wiring driving me nuts; what am I doing wrong?

Reply

  #1  
Old 11-11-12, 08:08 PM
Member
Thread Starter
Join Date: Nov 2012
Location: USA
Posts: 5
Old 3-way wiring driving me nuts; what am I doing wrong?

Attempting to troubleshoot/fix old 3-way switches between house and detached garage. 3-way capability has never worked in the 15 years I've owned the house -- the switch inside the house was basically an off-on, the one in the garage did nothing. I took it apart a year ago, got confused and left it, but now I'm trying to make it work.

After a weekend of head-scratching, it seems to work but only partially. If the switch inside the house is in the "up" position, the circuit works as expected, as determined by a plug-in tester (two amber lights, no red). But when I put the inside switch in the "down" position, it gets weird. The plug-in tester indicates "open ground", and the light only glows dimly. Checking it with an analog (not digital) multimeter shows about 50 volts across the circuit.

Attached is a jpeg that details what's happening in a given switch position. I had to trace this through about four boxes, from the switch in the kitchen, up to the peak of the house, down to the garage and to the 2nd switch.

I also drew diagrams showing what I think should be happening. It seems to work as expected if the house switch is in the "up" position, but not in the "down" position. The house switch is wired correctly with the hot feed to the common terminal. Any thoughts about improper connections or bad switches is appreciated. I don't know if this is relevant, but the switch in the garage looks like a regular single pole switch (small and narrow, not the larger block), but does have a black common terminal and two brass traveler terminals.

Thank you!
 
Attached Images  
Sponsored Links
  #2  
Old 11-11-12, 08:21 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 46,232
The pictures you drew are correct. You have the switches drawn right. Each 3 way switch has 3 screws. The odd color screw is common and it connects to one of the screws when the switch is up and the other screw when the switch is down. A start would be to give us the colors you have at each end of the circuit. You need to establish 3 wires between the home switch and the garage switch. Two will be travelers for the 3 way switches and the third is the neutral. Color pictures are good too.
 
  #3  
Old 11-12-12, 08:17 AM
Member
Thread Starter
Join Date: Nov 2012
Location: USA
Posts: 5
Name:  Wiring diagram -- house-garage 3 way.jpg
Views: 46512
Size:  33.4 KB

Thank you for the assistance. Unfortunately the colors won't help much -- they keep changing. The wires on the two travelers (brass screw terminals) from the house switch are white (!) and black, but when the cable emerges in the box up at the peak of the house, there are three wires -- red, black and white. Somewhere behind my kitchen cabinets/wall, there's obviously another box where the circuit picks up a neutral (there isn't one in the house switch box). And inside the garage, all the wires except for the neutral are black.

I'm guessing that in converting the overhead cable to the garage from four individual wires (1935 house) to a single cable, they did some kind of stupid jury rig that I now have to sort out. They also managed to use the bare ground wire as the neutral to the garage, when there is a perfectly good white wire available, but I fixed that.

The question I think boils down to, what kind of mis-wiring could result in a circuit that shows 1) open ground and 2) 50 volts of current, when alternate switch positions show a good circuit?

One other wrinkle is that in the garage, as you see in the diagram, the common from the switch there runs back up through the conduit to the point where wiring enters the garage and so I have three black wires and one white there. Could connecting the wrong two black wires cause this? I thought I had them correctly identified using my meter.

My next step is to start troubleshooting starting with the house switch and work my way through the circuit.......
 
  #4  
Old 11-12-12, 11:42 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 46,232
When I said color pics I meant of the actual wiring at the switches. No problem.

It's a little confusing because the wires keep changing colors but here are some things that you have to keep in mind. You need AT LEAST 4 wires to the garage to do what you want to do.

1) ground
2) neutral - for light and recp.
3) traveler - for 3 way
4) traveler - for 3 way

You'll need to feed the 3 way switch at the house end and take the load (lights) off the garage end. You have the garage end shown ok.
 

Last edited by PJmax; 11-12-12 at 11:45 AM. Reason: correcting
  #5  
Old 11-12-12, 04:08 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Have you tested for continuity to make sure the two travelers are the same to wires from switch to switch?

The 50V reading sounds like induced voltage. You should use an analog multimeter to block that out.

The diagram looks right.
 
  #6  
Old 11-13-12, 02:12 PM
Member
Thread Starter
Join Date: Nov 2012
Location: USA
Posts: 5
Thanks for the reply. I am using a small analog meter with a needle, not a digital. And the voltage is enough to dimly light my test light.

The only things I can think of are:

-- Although I thought I had them correctly identified, I could have swapped one of the traveler wires with the common lead that comes out of the garage switch and runs back up the conduit to the box at the peak of the garage - all three are the same color.

-- Something is wrong with one of the switches. The one in the garage is obviously very old -- it's narrow like a single pole switch, not the bigger block of new 3 way switches, but has the 3-way terminals on it.

-- Something odd in the wiring hidden behind the wall between the kitchen switch (since the wire type that exits the box in the kitchen isn't the same as the wire that comes out upstairs at the peak of the house)

Question: Could back feeding the wrong way through the switch (because I have wires swapped) give you the low voltage/open ground condition that my plug-in tester shows?

Like a I mentioned above, I'm going to start back at the kitchen switch with my meter and work my way though the circuit.
 
  #7  
Old 11-13-12, 06:41 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 46,232
It could show you low voltage if you were reading the voltage thru the filament of a lamp.
 
  #8  
Old 11-16-12, 01:10 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Could back feeding the wrong way through the switch (because I have wires swapped) give you the low voltage/open ground condition that my plug-in tester shows?
No, I don't think so. I think PJ has offered a more likely reason.

Question: In your attic, have you followed the cable feeding that box as far back toward the switch in the house as you can, to see if you can spot another box?
 
  #9  
Old 11-16-12, 04:32 PM
Andrew's Avatar
Member
Join Date: Apr 2003
Location: USA
Posts: 934
I think PJMax nailed it.
Andy
 
  #10  
Old 11-16-12, 08:34 PM
Member
Thread Starter
Join Date: Nov 2012
Location: USA
Posts: 5
OK, getting closer. Everything is good at least up to the peak of the house -- 120 volts from hot (black or red wire) to both the neutral and ground depending on switch position.

If I separate the neutral wires, so that there is no connection from the garage neutral f to the house neutral, that;s when I get the low volatage: meter held again hot lead from house and neutral returning from garage. I guess it must be what was suggested -- voltage feeding through a bulb filament.

But something is wrong/backwards in the garage, otherwise the wiring would work.... troubleshooting tomorrow....
 
  #11  
Old 11-16-12, 09:13 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
But something is wrong/backwards in the garage, otherwise the wiring would work.... troubleshooting tomorrow....
Well, for one thing you're testing against an open neutral!

OK, seriously now, if you make sure that the neutral gets all the way to the light, and ends where it's connected there, then everything should work.
 
  #12  
Old 11-19-12, 08:51 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 46,232
Glad you persevered and conquered your wiring gremlins



EEK.......I'm caught in time warp again.
 

Last edited by PJmax; 11-19-12 at 08:52 PM. Reason: Time warp
  #13  
Old 11-19-12, 08:55 PM
Member
Thread Starter
Join Date: Nov 2012
Location: USA
Posts: 5
OK, so I FINALLY figured out this friggin (stronger word deleted) thing. Turns out the light and outlet in the garage are NOT 3-way switch controlled -- they're powered by one of the travelers IN BETWEEN the two switches. So if the switch in the house is in the up position, they're powered, if it's in the down position, sending current to the other traveler, no power.

The only thing that's powered by the three way switch off the common in the garage is a lead to what was presumably a flood light at the peak of the garage. Which I finally figured out when I did some additional continuity testing. Found out I had wired it wrong -- three identical black wires and I picked the wrong two, apparently giving me my open ground reading.

Now, WHY it was wired that way is a mystery lost to the ages, but thanks for the help as I puzzled through this....
 
  #14  
Old 11-20-12, 08:53 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
I'm curious. What did you wind up doing? Did you change it so that everything in the garage is controlled by the 3-way pair?
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes