Greetings All,
Although I have a fairly adequate knowledge of things electric, I’m having an issue with a circuit in my house. A ceiling fixture is controlled by a couple of 3-ways. Hasn’t worked well since the electrician ran the circuit a while ago, but just never used it till now. Light won’t go on. Checked the obvious first, bulb is ok. While troubleshooting I noticed something weird. Voltage to earth ground should either be 120V or 0V, depending on the position of the switch. Travellers have 35V to ground. If I kill the breaker for this circuit, I still get 5v on the travellers. Here’s where it gets strange (at least for me). The travellers are disconnected at both ends, but still show 5V to the conduit. Conduit is not energized, checked for voltage to a cold water pipe and it shows 0V. I realized there is a hot wire from another circuit running in the same pipe as my problem circuit. If I kill that second circuit, voltage in problem circuit drops to 0V. Could the hot wire from the second circuit be inducing a voltage in my mystery circuit? I understand induction and how it works, just never thought I’d see it in house wiring. Is this a problem?
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You undoubtedly have a problem with your meter. Try using an analogue meter.
As for your problem with the light, I suggest you become familiar with 3 way switches and then figure out what you got.
~Peter
I used both digital and analog meters, same results. Already know how 3 ways work, thanks.
Bump.
I don't have an answer for you but I am interested to see what people come up with. Your thoughts on an induced voltage sound feasible but 5V sounds high. I would be more curious about the 35V. You have probably already done this but I would trace out the entire circuit. Checking for defective switches might be a starting point?
5 volts is LOW for a phantom voltage. It's more common for it to be in the 35-75 volt range.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
Phantom voltage. Caused by capacitance between the wires.
Use a mechanical voltmeter, or a digital one designed for electrical circuits that has a built-in load resistor.
Edited 3/27/2009 8:55 pm by DanH
Have you tried replacing the 3-ways?
Or, you just pull the light fixture out and test to see if there's power there
I'm guessing the electrician screwed it up somehow. Could be a loose connection somewhere, or an out-and-out wiring error.
You need someone who understands these things a little better to noodle it out.
Sounds like a miswired neutral. He has two circuits in the same pipe. the electrician may have shred a neutral or crossed them somwhere. May be and imbalanced load voltage.
Or, just something as simple as some skinned insulation on a hot somewhere. If the fan was added using an existing run of conduite he likely did a pull out/pull in, using one of the old wres for his pull wire. It is a pretty common way to add wires but if the conduite is crowded and the wires are not tapped to the pull wire correctly, it is easy to skin an existing wire durring the pull. ( don't ask me how I know)
Welcome to Breaktime Dave.
Be forewarned, there's another guy here with your peculiar last name. That could mean trouble.A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
If it was skinned insulation the breaker would blow or the light wouldn't go out.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
I have seen 277v absolutely rattle the pipe from skinned wires and not blow a breaker.
Strange things happen in the real world.
Yeah, but that's only because of that penny you put in the fusebox.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
Believe me, I've seen that and worse.
Like a piece of copper buss shoved in place of a buss fuse in a I've disconnect.
I worked in one facility that had both Delta and wye three phase. You had to be real careful to figure out which one you were working on, cause chances were that someone had haywired something in the past.
The problem of being an electrician at an electric utility company is that everybody that ever worked there thought they were electricians. No one ever bothered with the NEC because the first page exempted power companies from it. The old guys I worked for took that to mean everything the company owned, not just the generation and transmission facilities.
I am amazed that I survived my training sometimes :>)
Was working on a house down in Pass Christian that had been owned by a power company guy. He SORTA knew what he was doing, but we found a lot of scary stuff.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
Hey everyone. I have been building for years and reading FHB but never been into this part of FHB. I came across your 3-way electrical problem and it got me thinking about a situation I had.
The light won't turn on? Try turning one of the switches to the on position. Then go and turn the other switch to the on or off position whatever the case. If that does not work then go back and reposition the first switch and come back to the second switch and move it. If this lets the light work at one of the switches but not the other then you have a traveler/power(black) mixed up on one of the switches.
Another thing to think about, is the feed coming into the switch then switch then light, or switch, light, switch, or light, switch, switch (about 5-6 different ways to wire a 3-way)in any case some of these situations involve using the neutral(white) in different ways at the switch and/or at the light. This might explain why your getting a reading but not enough to run the switch and light. Maybe he didn't mark the neutral as hot if he used it this way or maybe he should have used it this way depending on the situation.
Maybe I have had too much to drink but there is not an off or on position on a three way IIRC. But then I am not an electrician, drunk or sober.
For those who have fought for it Freedom has a flavor the protected will never know.
Edited 3/29/2009 12:27 am ET by rasconc
There's such a thing as a sober electrician??
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
I do know one who has completed the 12th step. Sort of kidding but actually a friend at church did party a little too hard on many fronts and then decided that he needed to stay away from all of it. Now won't even drink a beer. I think they want to pull his license (:-). For those who have fought for it Freedom has a flavor the protected will never know.
Maybe I should have said"...move the switch lever on one of the 3-way switches in the opposite direction from which it was when first attempting to solve the problem of no power to the light and when that didn't work, relocate said switch to previous position. Then repeat process on second switch lever until....never mind. not enough time or space. Seriously, Thanks for letting me be part of the discussion.
Welcome to Breaktime and don't get discouraged too easily.
Please fill out your profile, thanks.A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Took the circuit apart and found a bad neutral connection. Still wonder what generates that phantom voltage though.....
Capacitance.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith