Problems with my two way switches need help

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  #1  
Old 01-06-12, 06:39 AM
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Problems with my two way switches need help

I changed all the plugs and switches in my house. they where all oem from the 1960 so I got new cooper once. No problems with any but the two way switches. Now I checked before I changed them. both switches worked, like you can turn the light on and off from either switch. I wired them up the same way there was a red black and white. most of the time some times red and two blacks. ran a tester on then to see what was the hot and neg. one. So red went on the left side that is the link between the two. the black is hot so its the top right and white neg gose on the bottom right. Now what happens is the light can go on and off with the one switch. If I turn on the switch to put the light on at the bottom of the stairs its on turn if off and on at the top of the stais its works fine. but if I turn if off at the bottom of the stairs and try and turn it on top of the stairs the lights dead? I have two halls and one outside light this happend too. I turnd the wires around all ways and it dose not work? How did it work fine with the old switches and I connected them the same way and it dose not work now? The funny thing it the garage two ways and other hall I changed worked fine. there wired the same way. Any help would be great.
 
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Old 01-06-12, 08:18 AM
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No such thing in US terminology as 2-way switch. Do you mean three way switches. (Having three screws plus ground.) Location of wires on 3-ways varies with manufacturer. What is important is that you keep the same wire on the common of the new switch that you had on the common of the old switch. Did you do that? The common is the odd colored screw. usually dark colored.

ran a tester on then to see what was the hot and neg. one
Negative is not applicable to AC circuits. All wires in a switch circuit are technically hots at some time.

There are many ways to wire a 3-way circuit. This is one typical way, yours may vary:

 

Last edited by ray2047; 01-06-12 at 08:44 AM.
  #3  
Old 01-06-12, 09:22 AM
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3 Way Switches

To in part echo the previous comment, My copy of The Visual Handbook of Building and Remodeling by Charlie Wing illustrates three methods of running these circuits and for all I know there are more. This may help some:
1) Light between the switches and the traveler runs between the switches through the fixture
2) Light beyond the switches and the traveler runs direct between the switches
3) Switches beyond the light and the traveler runs direct between the switches

I went through the same goat-rope in my place, except the previous occupants had lived with one mis-wired switch that I had to fix. I used a long wire with my multi-meter to get all the wires properly identified, after removing several layers of paint, and sketched out to figure out what the original electrician had done.

I suspect a mix-up at the switches because in:
#1 the grounded/neutral wire passes through the 1st switch box to the light but the black connects to white in the light fixture box and then on to the second switch
#2 the grounded/neutral wire passes through both switches to the light
#3 the grounded /neutral wire goes direct to the light and then the colors swap back and forth on the runs from the fixture to the switches. And the traveler doesn't run to the same position as in #1 & 2

And only by knowing which of the three methods were used can you figure out if a black is really a black at the switch to connect it to the proper screw. And as was noted, they vary between manufactures so that is probably the big clue, the old don't match the new. After editing this, I think I would first move the traveler on the switches as a quick check and then use my meter on the switches to see if the colors match.

Ron
 
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Old 01-07-12, 05:11 AM
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The best way for me to trouble shoot 3 way switches when I have no clue how the electrician before me wired them is as follows.
1- turn the power off for the circuit. 2- Disconnect the wires from both 3 ways and separate the wires so they are not touching. 3- Turn the power back on and use a meter to determine which wire is bringing the power into the circuit. 4- After you determine which switch has the power, turn the power back off and use an extension cord to stick the other two wires into the female end. At the other switch use a continuity tester and the other end of the extension cord to verify which is the travelers. 5- After you have these wires identified, In one switch you connect the hot wire to the odd colored screw and the travelers to the matching colored screws. In the other switch, you connect the travelers to the matching colored screws and the other wire to the odd colored screw. Your white wire or common wire should just pass thru each switch with wire nuts.

Hopefully this helps.

Mod note: This post may be confusing "neutral" and "common". See next post.
 

Last edited by ray2047; 01-07-12 at 06:22 AM.
  #5  
Old 01-07-12, 06:18 AM
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TRexkk wrote:
Your white wire or common wire should just pass thru each switch with wire nuts.
T There will also be white wires that are neutrals. A good electrician recolors white wires not used as neutrals but in practice that is seldom done despite code requirements to do so. Your statement though is a bit ambiguous. The commons are attached to the switch not just passed through. It is the neutrals that are usually tied together and passed through. It's almost as if you are confusing common and neutral, two very different terms.
 

Last edited by ray2047; 01-07-12 at 02:13 PM. Reason: Correct misstatement about code.
  #6  
Old 01-07-12, 12:56 PM
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If the 3 way switch is a dead end, the white should be the common. NEC 200.7.
 
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