I have a circuit in my house which has two three way switches and several lights. The switches do not turn the lights on, and the breaker is not tripped.
This circuit was wired when my house was built 16 years ago. It has been working all this time, until this evening.
The circuit had the two three way switches, a compact florescent bulb, 2 incandescent bulbs, and a 4 tube florescent fixture.
When I first found that it did not work, I replaced the compact florescent bulb with an incandescent bulb, but there was no change.
I opened the switch boxes and found that the switches had 120 volts. One terminal measured 55 volts on each switch. Thinking that the problem could be the switches, I got 2 new ones and replaced both of them. I was careful to put the wires on the new switches in the same manner as they were on the old switches. This did not help.
Before replacing the switches I located the breaker. It is labeled “misc” so it probably has other things on it as well.
Tomorrow I will remove the florescent fixture to see if it is the problem.
This is a new one for me. Something is open. Do you have any suggestions?
Thanks,
Allen
Replies
>>>One terminal measured 55 volts on each switch.
Loose or open neutral.
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
It's normal for the "off" traveler in a 3-way setup to measure 55 volts.
What is wanted is not the will to believe, but the will to find out, which is the exact opposite. --Bertrand Russell
Never thought of that.... is that because of the current passed to the neutral from the other traveller?Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
It's because the wire is disconnected and therefore "floats" between hot and neutral voltages.
What is wanted is not the will to believe, but the will to find out, which is the exact opposite. --Bertrand Russell
If the circuit has a load on it the traveler should only measure aprox 120 or zero.However with flourscents I am not sure what the characteristics are and if there are different between magnetic and electronic ballast. Thus in the off case they may appear to be an high impedence when there is no applied power.But in this case there was an incandenscent bulb in the circuit. That will "load" down the open traveler and read zero.One thing that can confuse things is if the switches are illuminated..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
When the switches are set to "on" the unused traveler is unconnected at both ends and will float to about 55V.
What is wanted is not the will to believe, but the will to find out, which is the exact opposite. --Bertrand Russell
Sorry, but my admittedly small understanding of electrical issues fails to see how a conductor, completely disconnected at both ends, could have any kind of voltage. What is the reference conductor that you are measuring against? Traveler to ground? Traveler to neutral? Or Traveler to other traveler?Thanks,Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
Everything has a voltage. This situation is known as "stray" or "phantom" voltage. It is caused by capacitance between adjacent conductors.
What is wanted is not the will to believe, but the will to find out, which is the exact opposite. --Bertrand Russell
And, in this case, since the voltage measured is about half of line voltage, you'll get about the same measurement when referenced to either neutral or hot.
What is wanted is not the will to believe, but the will to find out, which is the exact opposite. --Bertrand Russell
It's sometimes hard to troubleshoot with a voltmeter because it has really high impedance, so you could have a poor neutral connection that would read fine with the voltmeter.
It's sometimes useful to plug an extension cord into a different circuit and then use that as your voltage reference. That way you know that you have good references you can use to measure against. Somewhere in the FH archives there's an article named something like "working with old wiring".
Things it could be:
1) Could be a bad breaker
2) Could be an open neutral somewhere in the circuit.
My guess is #2
"Tomorrow I will remove the florescent fixture to see if it is the problem. "
The florescent has nothing to do with this.
You have 4 lights on this circuit. One of them won't keep the others from working.
It sounds like you are using a digital voltmeter. They have a high input impedence and with an open wire they will pickup electrical fields from other wires.
A reading that is not near 120 or zero means an open circuit.
"I opened the switch boxes and found that the switches had 120 volts. One terminal measured 55 volts on each switch."
You can't measure a voltage AT A POINT. Voltage on has a meaning when measured between TWO POINTS.
Often the 2nd point is clearly implied by the statement. But there are many ways to wire 3 way switches and you need to be clear about the what the 2nd point is.
http://www.selfhelpandmore.com/switchoutlet/3way/
"I was careful to put the wires on the new switches in the same manner as they were on the old switches. "
How did you wire them in the "same manor"?
3-ways have a common terminal and 2 travelers. The common will be one color and the travelers a different one.
The colors used and the location of the terminals on the body vary from brand to brand.
The only way to know for sure is to find the color that has 2 terminals and the color that has one terminal.
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
"I opened the switch boxes and found that the switches had 120 volts."
How did you test 120v? Hot to ground?
"One terminal measured 55 volts on each switch."
How did you measure 55 volts - from one terminal to what? If you are measuring from hot to one of the other terminals on the switch, you are probably measuring phantom voltage. Connect a small load [a little light bulb] between one of your tester probes and the "55V terminal", then touch the hot terminal with the other tester probe and voltage will read zero.
Other posters have suggested a loose neutral (white) wire connection somewhere. You probably have a two-wire cable [plus ground] and a three-wire cable coming into each box with the black wire of the two-wire cable connected to the common terminal of the switch and the white wire wire-nutted together with the white of the three-wire cable [whose black and red wires are connected to terminals on the switch].
If any of the white wire connections is faulty, in either box or at the connection to the first light, nothing works. Similarly, if the black wire is loose where it connects to the first light, nothing works.
"You probably have a two-wire cable [plus ground] and a three-wire cable coming into each box with the black wire of the two-wire cable connected to the common terminal of the switch and the white wire wire-nutted together with the white of the three-wire cable [whose black and red wires are connected to terminals on the switch]."Depends on how it is wired. Many wires of wiring 3-ways won't have a 2 wire cable at both ends and won't have a neutral in both boxes.And if he had a neutral in the reads that he got most like indicate that the neutra was good up to that point.A break on the load side of either the hot or the neutral would give him the readings that he had..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Bruce and all:
I hope this answer goes to all who wrote me on this topic. Thanks for your thoughts!
Armed with your insights, I checked my installation of the new switches and found that, as someone suggested, the terminal locations were different on the new switches. I corrected the wiring, and everything works great. And I did not spend the day looking in the wrong place.
Thanks again!!
When do you sleep?
Allen
Change out the switches. I had one go in my house that worked perfectly until I set it up as a rental. The switch went. Changed it out and everything is fine.