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Hey! Thanks for the replies to my previous post. My vote was also for induced voltage, so I thought an easy test would be to throw the main breaker on the panel and verify that the induced voltage disappeared.
So that’s what I did, and guess what? The voltages in each of the three “dead” circuits involved went up!!! They went from 11 vac to 18 vac and from 4.5 vac to 11.5 vac and from 4.5 vac to 11.5 vac.
Looking at the labels on the circuits, I discovered that all three of these circuits are feeding different rooms on the third floor. Coincidence?
The induced voltage argument still sounds good though, because the voltage went up when I threw the main breaker. Seems that induced voltage is 90 degrees out of phase with the original AC voltage, and so the house voltage has to “fight” through the induced voltage – or vice versa. With the house voltage eliminated, the induced voltage went up because it was not being reduced by the presence of any house voltage (even though there should’nt be any in these “dead” circuits”
Well, here’s the kicker. Where is the voltage coming from? If I look outside the third floor of this building, there is a power line pole with a bare copper conductor about 10′ away from the house at the same level as the third floor. I’ll bet money that this power company wire is throwing out of phase juice into my house, and that all the money and time I spent making sure that I had BX jacketed cable in every wire surrounding my bedroom so that I wouldn’t be affected by errant electrical fields from the wiring in the bedroom was a GREAT BIG WASTE – since I am being exposed to a MONSTER electrical field courtesy of my local power supplier.
To test this theory I will go out onto the third floor deck and see if I can measure the voltage induced in a 4′ long copper conductor. Should make for an interesting physics experiment.
Any input for alternate testing ideas or alternate hypotheses would be appreciated.
Thanks!
Replies
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If that wire is putting off that much magnetic field, it must be a pretty high current flowing through it.
For your test, keep the following in mind:
The current in your "secondary" (test) wire will be greatest if the two conductors are parallel.
The longer the conductors, the higher the current.
I'm interested to know your results. I love this science stuff.
Be careful. I was an engineer for my college radio station and one of the other engineers wrapped a lamp's cord through and around a metal ring about 6" in diameter and wrapped a piece of regular old wire around it also. If you touched the second wire with the lamp plugged in, you got a real solid jolt.
We also built a 2" square metal box with a small toggle switch on the top. It had a 9volt battery and a transformer in it. It looked harmless. When you flipped the switch on, nothing happened. When you released the switch, the magnetic field collapsed and the metal box was given a jolt of about 90V. We left it on the console in the studio and said nothing. There was alot of yelling on the radio that morning.
So what I'm saying is, sometimes induced currents can hurt you. (But they're alot of fun until the do.)
*Since my last post, I've really been thinking about this.Current (or voltage) is only induced if there is current in the other conductor. That means your wires would only pick up something like 11 volts if you were running some pretty big equipment on the other circuits.Are your neutrals and grounds tied into the new pannel? This may be the source of your voltage.Or, if you were using a digital volt meter and had it set to DC, you may be picking up some static charge. Digital volt meters have nearly infinate resistance between leads and static voltage can be picked up by them.
*I would suspect the multimeter.
*I'd be wondering about the breakers as well. Recent "experience" with a 60a/2 pole... I always test with Wiggies... why? Sometimes "off" - ain't.
*Had a new 200A main box installed on a house a few years back. A few circuits were wired up, etc. Came on the jobsite, turned off the main breaker, the eerie sound of rock n roll was still coming from the radio upstairs. Sobering. Turned out the main breaker was bad. When turned off, it would turn off one leg, the other was still hot.In talks with the manufaturer, 3 out of 1000 turn out bad. Their claim. They can test good at the factory, but somehow, somewhere, in the shipping/installation/wiring, the guts seemingly get knocked around just enough to cause metal-to-matal contact that shouldn't be there.Try tripping the main breaker and then check using your meter for any current between the neutral and the hot legs below the main breaker, on the bars that the breakers snap on to.Careful.
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This sounds induced to me. We see this all the time in our factory. Lots of 480V machines and a high impedance digital meter makes it look like there are high voltages on cicuits that are off. If you use an analog meter they'll all read zero. The amount of current that's being generated is nil. Probably :)
*
When I was a kid, I had a radio that needed no external source of electricity. It would play AM radio over an earphone. The only source of power was the radio waves. Today's multimeters must be a lot more sensitive than that earphone and the stray signals thousands of times more dense. You can get stray voltages that are not even 'induced' in the true sense of the word.
*I've never heard of any worries about "errant electrical fields" from 120V wiring using Romex vs BX cable. Has anyone else?One thing that has been mentioned a lot here is that digital voltmeters are often fooled. Their extremely high input resistance is what makes them very sensitive for electronics work, but often can give misleading readings on AC circuits. A solenoid type ("wiggy") tester is much more reliable on house wiring circuits. I have often seen similar situations to yours where I told the guys to "try again with the simple Simpson (analog meter)" and found stray voltages disappear. Hope this happens to you.
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Thanks for the ideas!
I'll check them out this week, when I get back to the house.
I was talking it over with an engineer friend of mine, and he thinks that it could well be induced voltage - especially when I told him the transformer for the house is only 10 feet away or so up at the third floor level. He said the hot wire for the transformer cans was around 7000 volts and that might be enough to induce the voltage. But he was skeptical that the EMF would be large enough to induce 18 volts from 10 feet away.
I will try the parallel conductors test with about 8 feet of wire, and maybe pick up a cheap analog meter, or maybe a Wiggy. The Wiggy i saw at the electrical store looked a lot like my Volcon tester. I know the Wiggy is a solenoid tester, but what would it read with these low voltages and even lower amperages?
Will post results soon,
robbwilson
*Suggest you pick up a Fluke 16 multi-meter.Fantastic tool. Has a feature called "vcheck" that measures voltage with someting like 2K ohms across the meter (instead of the meg-ohms that typical digital DMM has). Will not be fooled by induced voltage.The meter also has ability to measure temp with a simple thermocouple--great for HAVC or even checking the temps on your fridge (home or RV). Lastly, this meter has a min-max recording feature that will time stamp the high and low value of voltage or temp. Excellent for nailing intermittant problems. You don't have to camp on the meter to catch an event. Oh, yea, it also measures high values of capacitance--so you can directly measure motor starting caps. Many other neat features. Bad news, it runs about $130. But if I were gonna get just one meter for electrical troubleshooting and general use, it would be the Fluke 16.
*
Don't you remember all the rumors about EMF maybe a dozen years ago? That they caused various medical illnesses? There hasn't been much to back it up, although it was enough to make me nervous about my electric blanket.... There was a story just recently that in one of the major studies supporting a link between EMF and illness, the data was faked.
My old Beckman electronic multimeter would get very confused around fluorescent lights unless connected properly to a circuit of some sort -- again because of the high internal impedance.
Here at least, the pole voltage is 19.1 kv.
*Yeah, I get confused every time I mess with those fluorescent lights.Rich Beckman
*Hey, and that darn thing broke 15 years ago when I hooked it up to the wrong end of my Tesla coil. When are you going to give me my money back?
*As soon as they give me my stock options...and you come up with the receipt.Rich Beckman
*Now you know why everyone's going over to Fluke... (a name that always made me nervous)
*Mongo, the 3/1000 won't go dead if flipped manually, or won't trip period? If that many won't react to overamperage, it's a pretty horrifying failure rate.I've wondered whether there would be any point in deliberately overloading circuits to test the breakers -- not something I'm comfortable doing without good reason. How DO we know these things will work in time to stop a fire? There's no "self test" like on a GFCI. I'd assumed they were pretty reliable.
*Just for fun, we used to keep a flourescent tube on top of the machine at work that dielectrically bonded vinyl seams together. The bulb would fully lite up every time the machine was energized (no other connection, just one of those flourescent tubes, laying there). I was always glad that I did not work in that room....
*Well, fluorescent tubes (note that there's no flour in them) are pretty efficient, once you get past the ballast and electrodes. But I'd stay away, too, in fact I try to find stuff to do elsewhere whenever the microwave is running.
*Dr. David Banner had a fluorescent tube in his lab that did the same thing. Then one day...
*
Hey! Thanks for the replies to my previous post. My vote was also for induced voltage, so I thought an easy test would be to throw the main breaker on the panel and verify that the induced voltage disappeared.
So that's what I did, and guess what? The voltages in each of the three "dead" circuits involved went up!!! They went from 11 vac to 18 vac and from 4.5 vac to 11.5 vac and from 4.5 vac to 11.5 vac.
Looking at the labels on the circuits, I discovered that all three of these circuits are feeding different rooms on the third floor. Coincidence?
The induced voltage argument still sounds good though, because the voltage went up when I threw the main breaker. Seems that induced voltage is 90 degrees out of phase with the original AC voltage, and so the house voltage has to "fight" through the induced voltage - or vice versa. With the house voltage eliminated, the induced voltage went up because it was not being reduced by the presence of any house voltage (even though there should'nt be any in these "dead" circuits"
Well, here's the kicker. Where is the voltage coming from? If I look outside the third floor of this building, there is a power line pole with a bare copper conductor about 10' away from the house at the same level as the third floor. I'll bet money that this power company wire is throwing out of phase juice into my house, and that all the money and time I spent making sure that I had BX jacketed cable in every wire surrounding my bedroom so that I wouldn't be affected by errant electrical fields from the wiring in the bedroom was a GREAT BIG WASTE - since I am being exposed to a MONSTER electrical field courtesy of my local power supplier.
To test this theory I will go out onto the third floor deck and see if I can measure the voltage induced in a 4' long copper conductor. Should make for an interesting physics experiment.
Any input for alternate testing ideas or alternate hypotheses would be appreciated.
Thanks!