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Replacing Two Three-Way Switches -- problem with replacement switches ..

Replacing Two Three-Way Switches -- problem with replacement switches ..

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  #1  
Old 11-16-13, 03:34 PM
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Replacing Two Three-Way Switches -- problem with replacement switches ..

I have two three-way switches at the bottom and two at the top of my stairs that control lights at each location. I replaced the two switches at the bottom of the stairs (old-fashioned single unit three-ways) with a single wall unit with two three-way switches. Each of the two three-ways requires three wires -- a hot and then two other on the same side. I tried to place the old wiring in the same spot on the new switches. I am sure that the hot wire is on the correct side (it registers on my voltmeter when grounded).

Result -- each new switch downstairs and upstairs works in turning on and off the top and bottom lights. But ... if the top switch turns off the lights, the bottom switch cannot turn them on again; if the bottom switch turns off the lights, then the top switch cannot turn them off. I have tried every possible combination for the four wires and cannot find the right one. I have tried many combinations but none works. What is my problem?

Is it possible that my three-way switches at the top of the stairs are incompatible with the new three-way switches at the bottom? How do I test with my voltmeter the four wires in the switch downstairs to determine where each should be attached should be attached on the two new three-way switches. Do I need a three-way tester and then what?

None of the wires is marked in the old house but the hot was easy to identify because it was connected -- same wire -- to the two hots on the old switches downstairs (and it shows current when grounded to the box).

Thanks for your help ....

Peter
 
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  #2  
Old 11-16-13, 04:16 PM
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The hot wire and the "load" wire to the light fixture (s) will be put on the andonized or dark colored screw. The other two don't matter, as long as they are attached to the screws. Your older switch may have had the dark screw in a different location. So you'll need to determine the hot and the load wire at each switch, and work from there. Let us know if we can help further . You may want to post pictures of the switches pulled from the boxes so we can see what you see. http://www.doityourself.com/forum/el...your-post.html
 
  #3  
Old 11-16-13, 05:30 PM
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Thanks for your prompt reply. As noted in my question, I have identified the hot because my voltmeter shows that it is active when grounded to the circuit box. My problem is that where the other wires are attached does appear to make a difference. Specifically, there are four wires -- two for each of the two three-way switches. As noted, I have the right wires to the right lights but ... I have the problem discussed (top switches off, cannot turn on downstairs and vice versa). So my problem is one step beyond simply identifying the hot wire. I will take pictures but the wires do not reveal the order to be installed. There are a total of four and two obviously go to each switch. Is there some way to test the wires to determine which go to which switch (and which to which part of the switch -- it does seem to make a difference this time) or whether I need different three-way switches at the top of the stairs where I have touched nothing. I appreciate your help. Peter
 
  #4  
Old 11-16-13, 05:49 PM
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Three way switches require three wires...hot/load and two travelers per switch. Got pictures?
 
  #5  
Old 11-16-13, 06:38 PM
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This is how a 3 way should be set up...

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Now the only difference in your setup is that your hot coming into the box should be pigtailed with two wires, one for each switch.
Your 4 leftover wires should be 2 blacks and 2 reds coming from two different cables.
One set of black and red is for one switch, and the other set for the other switch.
Verify at the 3 ways you did not touch that they are wired correctly.
At the top of the stairs shoud be 2 two wire cables for your lights. the whites all go together in that box, and each black should go to a separate switch.
As chandler pointed out, you should have 3 screws on the sides of the switch, and one of them will be darker, labelled "common", or something to make it stand out. Please note you may have a green ground screw attached to the frame of the switch. This is for ground only.
Your pigtailed blacks go to the black or common screws, and the blacks from the lights go to the black or common screws.
Your situation sounds like your hots, legs, and travelers are simply not wired correctly.
 
  #6  
Old 11-16-13, 06:51 PM
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It's doubtful the new switches are *incompatible* especially if they are mechanical.

I don't think you're quite grasping what Chandler has properly laid out in his posts.

The 4 wires you are referring to are the *travellers* between the upper and lower 3 way switches. These don't matter which *traveller* screw they connect to.
What is important is the *hot* and the *load* ( which connects to the light ) requires to only connect on the *common* screw. This screw is typically black or darker colored than the traveller screws.

If you mixed up a traveller and the hot you will experience what you are seeing.
 
  #7  
Old 11-16-13, 07:01 PM
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Not to throw in any more confusion --- you might come across seeing the travellers being black and white ( reidentified ) conductors.
 
  #8  
Old 11-16-13, 08:52 PM
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Thanks for all this good help. I have the common to the black screw and now both downstairs and upstairs controls work for upper and lower lights. However, it seems to matter which traveler goes where on the new downstairs switch double three-way. After a little switching around, I found the right combination to make both upstairs and downstairs work. There is still one issue if the upstairs turns off both lights and then downstairs tries to turn on (e.g., downstairs switches become reversed -- i.e., upper switch turns off downstairs and lower switch turns on upstairs!). I tried to correct and only messed up worse so I can live with this. I suspect that the problem may be because of the old three-way switches upstairs where I have no opened the box. Any ideas welcome.
 
  #9  
Old 11-16-13, 09:01 PM
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It sounds like you have the travelers mixed up between the two separate three way switch systems. At some point you would need to open both boxes and with the help of a second person re-identify all the travelers with an ohmmeter or continuity checker.
 
  #10  
Old 11-17-13, 07:56 AM
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I suspect that the problem may be because of the old three-way switches upstairs where I have no opened the box. Any ideas welcome.
i don't believe there's an issue with the old switches, especially if things worked *before* you started making changes.
Your current issue stems from confusion in the wiring of the *new* switches.



However, it seems to matter which traveler goes where on the new downstairs switch double three-way. After a little switching around, I found the right combination to make both upstairs and downstairs work. There is still one issue if the upstairs turns off both lights and then downstairs tries to turn on (e.g., downstairs switches become reversed -- i.e., upper switch turns off downstairs and lower switch turns on upstairs!).
Actually it *doesn't* matter which traveller goes on which traveller screw.

What does matter --- the correct traveller wires from the correct cable are connected to the correct switch.

In your case you have 2 cables connecting 2 different pairs of 3 way switches.
Each cable contains a number of colored wires which are connected to the corresponding switches

For example ................ let's call them cable A for the upstairs light --- cable B for the downstairs light.

The wires in cable A are connected to the pair of switches ( upper & lower ) that control the upstairs light.

With the same thing for cable B --- the wires in that cable connected to the pair of switches ( upper & lower ) that control the downstairs light.



It sounds as though you have a traveller from cable A & B crossed over to the wrong switch.

Typically it's easy to see the grouping of the wires to see which *cable* they belong to. My suggestion is to look over the traveller wires and see which 2 are crossed.



Hopefullt this helps.
 
  #11  
Old 11-17-13, 01:05 PM
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Shot in the dark here...

Are you 100% positive you bought new 3-way switches?

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