3-way switch question
#1
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Thread Starter
3-way switch question
I tried replacing a 3-way switch that seems to be faulty. The light does not always come on, but you can pound on the wall near the switch and then it will usually work.
Looking at the new switch, it is a mirror image of the old one--two screws on the left and "common" on the lower right, rather than two screws on the right and "common" on the lower left. So I attached the wires to look the same except on opposite sides. But the bulb did not light when switched. So I reinstalled the old one for now. I assume the new one is not really the problem.
I am wondering if maybe because of the way the circuit is wired, or the nature of the switch, I cannot just follow the same connection pattern.
I do not know if this circuit is panel-switch-switch-light or panel-switch-light-switch. Or if that would matter.
I am not sure how to proceed.
All help greatly appreciated.
Gary
Looking at the new switch, it is a mirror image of the old one--two screws on the left and "common" on the lower right, rather than two screws on the right and "common" on the lower left. So I attached the wires to look the same except on opposite sides. But the bulb did not light when switched. So I reinstalled the old one for now. I assume the new one is not really the problem.
I am wondering if maybe because of the way the circuit is wired, or the nature of the switch, I cannot just follow the same connection pattern.
I do not know if this circuit is panel-switch-switch-light or panel-switch-light-switch. Or if that would matter.
I am not sure how to proceed.
All help greatly appreciated.
Gary
#2
Member
It's panel switch switch light. Do you have a multimeter to determine the hot wire coming from the terminal?
#3
Ensure the hot and load wires are connected to the black or anodized screws of the switches. Usually a black wire, but you should make sure. The other two, usually red and white connect to the other screws, but in no particular order. Not all switches are the same, so mirroring may not work.
Last edited by pcboss; 08-08-14 at 03:48 PM.
#4
The wire that came off the dark color screw on the old switch MUST go to the dark color screw on the new switch. Order or side is of no concern.
#5
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Looking at this switch, I have common on the upper left; in the "off" position, this terminal reads 15, the upper right white wire reads 120 and the lower right black wire reads 0. In the "on" position, the common reads 15, upper right white wire reads 120, and lower right black wire reads 120.
#6
I'm not quite sure what you are trying to measure but you should have one traveler that stays hot in either position. You should have another traveler that stays at 0v. The common should read 0v in one position and 120v in the other position.
#7
I have common on the upper left
in the "off" position
the common reads 15, upper right white wire reads 120, and lower right black wire reads 120.
#8
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OK. I can see that I am all wet here.
Looking at it again, the lower right screw is darkened and says "common." This reads 0 when the light is not on and reads 120 when the light is on.
The upper left screw is silver and reads 15 when the light is on and 15 when the light is off.
The upper right screw is silver and reads 120 when the light is off and 120 when the light is on.
This is a staircase switch. It has worked consistently until recently. Now when you flip it on, the light might turn on, or it might just flash and then turn off, or never turn on. If you flip it to "on" and the bulb does not light, or just flashes then turns off, you can try again and again, or sometimes pound near the switch, and the light will usually come on.
Looking at it again, the lower right screw is darkened and says "common." This reads 0 when the light is not on and reads 120 when the light is on.
The upper left screw is silver and reads 15 when the light is on and 15 when the light is off.
The upper right screw is silver and reads 120 when the light is off and 120 when the light is on.
This is a staircase switch. It has worked consistently until recently. Now when you flip it on, the light might turn on, or it might just flash and then turn off, or never turn on. If you flip it to "on" and the bulb does not light, or just flashes then turns off, you can try again and again, or sometimes pound near the switch, and the light will usually come on.
#9
Remove the switches and lay them on a table. Separate the wires from the switch, red, white, black and ground. Test the wires to ground for voltage. Black should be 120v on one switch and 0 on the other one. The one with 120v will be LINE. Connect that black to the anodized screw and the other wires to the other screws, ground to green screw. Do the same at the other switch, black to anodized screw, etc. Test to see if the light works. You'll go crazy with phantom voltage and a digital meter.
#10
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Thread Starter
OK. Let me try again. I have been mis-describing the problem.
With the old switch, you could turn the light on from upstairs or downstairs. With a new switch, you lose this feature. You cannot turn on the light from either end. One switch has to be in a particular position. The new switch looks like the old (3 contacts, one says "common" and has a dark screw, and there is no ground). But it doesn't work like the old.
The shorting problem seems to have disappeared, but now you cannot turn the light on from either switch. If the downstairs switch is in one position, the upstairs switch will not turn on the light.
With the old switch, you could turn the light on from upstairs or downstairs. With a new switch, you lose this feature. You cannot turn on the light from either end. One switch has to be in a particular position. The new switch looks like the old (3 contacts, one says "common" and has a dark screw, and there is no ground). But it doesn't work like the old.
The shorting problem seems to have disappeared, but now you cannot turn the light on from either switch. If the downstairs switch is in one position, the upstairs switch will not turn on the light.
#13
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Thread Starter
Downstairs, the wire connected to the "common" screw is red. Upstairs, it is black. The only red wire in the upstairs box is wirenutted at the back of the box. It doesn't terminate in that box.
Yes, I guess the other screws are brass colored. And, I guess the new switch that I bought does have a green screw; the old one does not.
Yes, I guess the other screws are brass colored. And, I guess the new switch that I bought does have a green screw; the old one does not.
#15
The only red wire in the upstairs box is wirenutted at the back of the box.
#16
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Thread Starter
The new switch doesn't say "off" or "on."
In the upstairs box you can see a red wire coming out of a 3-wire black sheath; it is wirenutted to 2 blacks and then goes back down the wall. The black and white from that 3-wire were connected to the brass terminals of my switch.
The wire that was connected to the "common" screw comes from another Romex in the box, a black wire coming out of a 2-wire cable.
In the upstairs box you can see a red wire coming out of a 3-wire black sheath; it is wirenutted to 2 blacks and then goes back down the wall. The black and white from that 3-wire were connected to the brass terminals of my switch.
The wire that was connected to the "common" screw comes from another Romex in the box, a black wire coming out of a 2-wire cable.
#20
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if you did not open up any wire nuts ........the wiring sounds correct.
the downstairs switch could be bad....install the new switch downstairs keeping the red wire on the common screw.
does the downstairs switch box have one cable only with the red to the common and the black and white to the 2 brass screws.
the downstairs switch could be bad....install the new switch downstairs keeping the red wire on the common screw.
does the downstairs switch box have one cable only with the red to the common and the black and white to the 2 brass screws.
#21
I'm trying to figure out your description of the switch at the top. How can this diagram be changed to be correct. (Cable sheath colors are only for identification and may not match yours.)
#22
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The upstairs box is crowded, (three 2-wire cables, one 3-wire cable, two wire nuts joining multiple wires from these cables, and multiple ground wires neither attached to anything nor bound together).
ray2047's diagram would be changed this way: the black and white from the 3-wire cable go to the brass screws. The black from the 2-wire cable goes to the dark screw (marked "common").
The white from the 2-wire goes to a wire nut. So does the red. There are 2 big wirenuts; I'm not sure if these go to the same wirenut or different ones.
The only thing in the downstairs box is a 3-wire cable with an unused ground. The red goes to the dark screw on that switch and the white and black go to the brass screws.
For johnsc: yes, the downstairs box has only the 3-wire cable, attached as you described.
I have not opened any of the wirenuts or done anything else. I have only tried to replace the upstairs switch with one that appeared identical and when I did this I could no longer turn on the light from either switch regardless of the position of the other switch.
ray2047's diagram would be changed this way: the black and white from the 3-wire cable go to the brass screws. The black from the 2-wire cable goes to the dark screw (marked "common").
The white from the 2-wire goes to a wire nut. So does the red. There are 2 big wirenuts; I'm not sure if these go to the same wirenut or different ones.
The only thing in the downstairs box is a 3-wire cable with an unused ground. The red goes to the dark screw on that switch and the white and black go to the brass screws.
For johnsc: yes, the downstairs box has only the 3-wire cable, attached as you described.
I have not opened any of the wirenuts or done anything else. I have only tried to replace the upstairs switch with one that appeared identical and when I did this I could no longer turn on the light from either switch regardless of the position of the other switch.
#23
and multiple ground wires neither attached to anything nor bound together).
ray2047's diagram would be changed this way: the black and white from the 3-wire cable go to the brass screws.
The white from the 2-wire goes to a wire nut. So does the red. There are 2 big wirenuts; I'm not sure if these go to the same wirenut or different ones.
#25
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One wirenut holds the red and 2 blacks. The other wirenut holds 3 whites.
I tried replacing the lower switch and got the same result. The light will not go on from either switch.
I tried replacing the lower switch and got the same result. The light will not go on from either switch.
#26
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Thread Starter
The switch in your diagrams is different from mine. Mine has the two brass screws across from each other, rather than on the same side. So I am not sure which is the traveler on mine. But otherwise this is correct--the black and white from the 3-conductor go to the brass screws and the black from a 2-conductor goes to the "common;" the white from that 2-conductor wire goes into the wirenut containing 3 white conductors.
I don't know if this matters, but the screws on my replacement switch are silver rather than brass.
I don't know if this matters, but the screws on my replacement switch are silver rather than brass.
#27
Common always goes to the odd colored screw switch regardless of position.
That is unusual. I would wonder if it was a 3-way switch.
Looking at my diagram where does the third white come from?
Is this the wiring for the downstairs switch?
but the screws on my replacement switch are silver rather than brass.
the white from that 2-conductor wire goes into the wirenut containing 3 white conductors.
Is this the wiring for the downstairs switch?
#28
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Common always goes to the odd colored screw switch regardless of position.
That is unusual. I would wonder if it was a 3-way switch.
Looking at my diagram where does the third white come from?
Looking at your diagrams, I see your switch is different from my existing switches and my replacement switches. Your diagram has the brass screws on one side and the dark screw on the other. On mine, the "brass" screws are across from each other; this is true of my replacement switch and both existing switches.
Is this the wiring for the downstairs switch?
#29
Please stop concerning yourself with the position of the screws on the switch. That doesn't matter. What matters is the common wherever it is. The screws look brass to me.
I don't believe Larry's diagram represents what you have. The screws on your new switch look brass to me. Try replacing the upstairs switch with a new one also. Your connections do look correct in bot boxes. Revised diagram:
I don't believe Larry's diagram represents what you have. The screws on your new switch look brass to me. Try replacing the upstairs switch with a new one also. Your connections do look correct in bot boxes. Revised diagram:
#30
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Thread Starter
The revised diagram does look correct to me.
When I replace both with new switches, I get the same result: you cannot just turn on the light from either switch. I have not tried moving the black and white wires to the other brass screw on either switch.
When I replace both with new switches, I get the same result: you cannot just turn on the light from either switch. I have not tried moving the black and white wires to the other brass screw on either switch.
#31
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Thread Starter
Well, I bought a new 3-way switch and installed it upstairs, and everything seems to be working ok. Thank you for all the terrific guidance.
I put an ohmmeter on the two other "new" ones I was using. They don't work the same. When you connect common with one of the brass screws and flip the switch, the ohms moves from 1 to 0; connect common with the other brass screw and it does the same. On the second "new" switch, when you connect common with one of the brass screws and flip the switch, the ohms moves from 1 to 0; connect common with the other brass screw and flip the switch and it stays on 1.
Would you agree this is probably what was happening? Bad replacement switch?
I put an ohmmeter on the two other "new" ones I was using. They don't work the same. When you connect common with one of the brass screws and flip the switch, the ohms moves from 1 to 0; connect common with the other brass screw and it does the same. On the second "new" switch, when you connect common with one of the brass screws and flip the switch, the ohms moves from 1 to 0; connect common with the other brass screw and flip the switch and it stays on 1.
Would you agree this is probably what was happening? Bad replacement switch?