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Old 04-25-2013, 03:06 PM   #16
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Funky voltage (at least to me)


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Originally Posted by gregzoll View Post
It would be if it stayed. It was just stored capacitance, that discharged, due to having the meter on the line.

Again, nothing to worry about, or as usual have some that want to turn these threads into pissing matches as usual.
I thought the OP said he hadn't installed the GFCI yet, so where was the capacitor?

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Old 04-25-2013, 06:16 PM   #17
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I thought the OP said he hadn't installed the GFCI yet, so where was the capacitor?

Mark
Gueesing you cannot read too well. I am not going to repeat ot, so you will have to go back and read from the beginning for what I stated.

Sorry, but I am not going to draw a picture for you, if you cannot comprehend how electronic testers and gfci outlets or even gfci & afci breakers contain capacitors.
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Old 04-25-2013, 07:45 PM   #18
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Thanks for your input guys!

Put it in and every thing works and checks out just fine but, just in case, I changed the batteries on the smoke detectors.

Now, if I could only stop my 110v air compressor from tripping my ground fault breaker.

Thanks again.
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Old 04-25-2013, 07:48 PM   #19
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Thanks for your input guys!

Put it in and every thing works and checks out just fine but, just in case, I changed the batteries on the smoke detectors.

Now, if I could only stop my 110v air compressor from tripping my ground fault breaker.

Thanks again.
It is tripping, because the motor is leaking current to ground.
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Old 04-25-2013, 08:16 PM   #20
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Funky voltage (at least to me)


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Originally Posted by MickeyBee View Post
Now, if I could only stop my 110v air compressor from tripping my ground fault breaker.

Thanks again.
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Originally Posted by gregzoll View Post
It is tripping, because the motor is leaking current to ground.
Accurate and reasonable response.
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Old 04-26-2013, 06:01 AM   #21
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Gueesing you cannot read too well. I am not going to repeat ot, so you will have to go back and read from the beginning for what I stated.

Sorry, but I am not going to draw a picture for you, if you cannot comprehend how electronic testers and gfci outlets or even gfci & afci breakers contain capacitors.
I believe I read the whole thread and understood what the OP said quite well. He said that he used a Sperry "bug-eye" tester first on a live outlet and it tested fine. The Sperry tester does not have any capacitors in it, just diodes.

He then shut off the outlet and tested 3V, then 10V then 0V with a VOM of unknown quality. The reading of 3V then 10V is NOT consistent with a charged capacitor. A capacitor cannot increase it's voltage without an external source (an inductor can).

So, if you want to tell me where this capacitor is and explain how it raised it's voltage all on it's own, I'm listening. Otherwise, there just isn't enough information to answer this question and you are taking stabs in the dark with your capacitor theory. If we were there and could reproduce the effect, then we could probably determine the cause.

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Old 04-26-2013, 06:54 AM   #22
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Since this thread is probably going to go down in another flaming heap of Greg's vague ramblings without any facts, I thought I should try to answer the OP's question to the best of my ability based on the information given.

I can think of at least two possible causes for the voltage you measured. The most likely is what is commonly referred to as phantom voltage. This effect is cause by capacitive and inductive coupling from a wire energized with AC voltage/current to an isolated wire. The effect is primarily capacitive. You can get these reading (and they do fluctuate) when you measure a wire with a high-resistance voltmeter. Most of today's voltmeters have very high resistance. In order to determine whether you have a dangerous voltage, you really need to measure with a lower resistance voltmeter such as an analog meter (needle), a solenoidal tester (Wiggy) or a low resistance digital (like the Fluke T+).

Another possibility, but unlikely is that the neutral in your circuit could be shared with another circuit. If this was a multiwire circuit and you disconnected one of the hot conductors, then that hot conductor (the load side) is now just connected to the neutral. If you measured from hot to ground, you could see the fluctuating voltage due voltage drop with changes in current on the load of the still operating half of the circuit. This is very unlikely due to the number of things that would have to line up for you to get this measurement and also the fact that you completed the project without getting shocked.

Bottom line, if you want to be sure that a circuit is safe to work on, you need to test using a relatively low resistance voltmeter between each and every wire and a known good ground. That tells you that the circuit is safe (at that instant in time). The only way to be truly safe against future future energization of the circuit would be to bond an equipotential zone, but this is only done in medium and high voltage applications.

I wish I could answer your question with more certainty, but without being there to investigate it, there just isn't enough data.

Mark

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Old 04-26-2013, 07:47 AM   #23
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busman, but the capacitor in a gfci, or even a cfl on the circuit, after voltage has been turned of can show enough when testing. As you continue to keep the tester on the line, which creates a load, it will bleed off any remaining voltage out of the capacitors in the cfl or gfci, until you get a zero reading. It should only read about 3 volts, but the amps would be read as milli-amps.

As for ramblings, sorry, wrong on that, if for somehow you think that I am just spouting out something I know nothing about. Remember, I grew up around electronics and electrical, due to the type of work my father did for the telephone company, and as a Radio man in the Air Force, along with I was also in the Navy doing electronics and electricity.

What we are talking about, is basic electronics, not some bs that is being made up.
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Old 04-26-2013, 07:51 AM   #24
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busman, but the capacitor in a gfci, or even a cfl on the circuit, after voltage has been turned of can show enough when testing. As you continue to keep the tester on the line, which creates a load, it will bleed off any remaining voltage out of the capacitors in the cfl or gfci, until you get a zero reading. It should only read about 3 volts, but the amps would be read as milli-amps.

As for ramblings, sorry, wrong on that, if for somehow you think that I am just spouting out something I know nothing about. Remember, I grew up around electronics and electrical, due to the type of work my father did for the telephone company, and as a Radio man in the Air Force, along with I was also in the Navy doing electronics and electricity.

What we are talking about, is basic electronics, not some bs that is being made up.
Yes, but you still haven't explained how the voltage on a capacitor went from 3V to 10V. If it weren't for that fact (as reported by the OP), I might consider a capacitor as a possible explanation.

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Old 04-26-2013, 08:00 AM   #25
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Yes, but you still haven't explained how the voltage on a capacitor went from 3V to 10V. If it weren't for that fact (as reported by the OP), I might consider a capacitor as a possible explanation.

Mark
The 3 to 10 would be due to the tester, when placing on the line, but as they saw, the voltage dropped, did not stay at 10v, after leaving the tester on the line.

Now it is possible that they placed the leads on the line first, then turned it to the AC 200v AC reading, or it could be that there was enough surge voltage at the leads, waiting for it to be connected to a device, or wiring circuit, is why they saw the jump.

But it should never do that, so I am going with a bad tester, which they can go bad out of the box, or over time, or if they have been accidentely dropped, only the OP knows.

Another possibility is that the batteries are going bad and need changed in the tester, which can also cause funky readings.
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Old 04-26-2013, 08:03 AM   #26
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The 3 to 10 would be due to the tester, when placing on the line, but as they saw, the voltage dropped, did not stay at 10v, after leaving the tester on the line.

Now it is possible that they placed the leads on the line first, then turned it to the AC 200v AC reading, or it could be that there was enough surge voltage at the leads, waiting for it to be connected to a device, or wiring circuit, is why they saw the jump.

But it should never do that, so I am going with a bad tester, which they can go bad out of the box, or over time, or if they have been accidentely dropped, only the OP knows.

Another possibility is that the batteries are going bad and need changed in the tester, which can also cause funky readings.
Yes, batteries could be another cause. So, I think we've both come to the same conclusion; there is not enough information to figure out the cause.

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Old 04-26-2013, 08:07 AM   #27
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I just tried my Sperry on a dead circuit, with a fresh battery, and not turned on. I got 3 volts as soon as I turned it to 200v AC setting, then dropped within less than five seconds to zero volts. Last night I was using it with the same battery that has probably been in it for over six years, and was getting funky volt readings. Got around anywhere from 110 to 116. New battery, got correct voltage reading.

So I am going with you busman, possibly bad battery and other causes.
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Old 04-26-2013, 09:01 AM   #28
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This discussion reminds me of a graduate level electrical/electronics measurement class I took 40 years ago. During the final exam one of the practical lab stations consisted of two terminals and we were asked to determine what was connected to them using all of the instrmentaion available. I drove myself nuts for over 20 mins before I realized I did not turn the circuit on!!! DUH. you can measure almost anything, real or not. The results are subject to interpretation. Using measuring equipment requires knowledge of the equipment. 0 does not always mean 0.

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Old 04-26-2013, 01:26 PM   #29
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It is tripping, because the motor is leaking current to ground.
I have absolutely no doubt in your wisdom but, in this case, their may be more culprits.

I was tired of moving extention cords to power my small wood shop so I put in a circuit with 3 outlets controlled by a ground fault breaker in a sub. I have yet to play with all the on/off time variables for each piece of equipment and, because the circuit is so new,the compressor was mentioned only because it was the first to break the circuit. Since then, I have been able to mess with it a bit more. Cycling the compressor was a pain so I moved to the chop saw. The first thing I noticed is that it (chop saw) will always tripped the breaker (ground fault type in sub) the first time it is started after it (or possibly the whole circuit) has remained idol for more than a half an hour. Any attempt to run that tool within that half hour wouldl result in a successful start. The saw has two prongs so my guess is that it is dbl insulated, if that matters. The only other tool that was tried was a Dremel which also tripped the GFCI after the circuit had remained idol for over an hour.

Any ideas?

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