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Old 03-22-2013, 09:48 PM   #1
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Voltage on line that is turned off?


I've been having some odd electrical issues tonight... have a hum coming from the service panel that starts quiet gets louder to a point then goes back down... kinda like a sine wave pattern but it takes about 10 seconds to cycle...

so I checked new lines that were ran for the basement... on the outlets I don't get zero volts..


Ground to neutral 0.0v
Hot to ground 0.255v
Hot to neutral 0.256v

this breaker is off... I expected 0.0 for all connections, but all the lines in the house are running in a bundle basically parallel for 50 ft to get to this point... could this voltage be coming from induction? Or is it normal to get a low voltage from hot to neutral or ground when a breaker is thrown off?

When the breaker is on, I get 125v

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Old 03-22-2013, 10:01 PM   #2
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Voltage on line that is turned off?


The voltage could be Phantom Voltage. The DMMs will read that.

The humming could be a loose connection in the panel, neutral perhaps, or maybe a breaker isn't seated well?

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Old 03-22-2013, 10:15 PM   #3
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Voltage on line that is turned off?


Almost certainly it is phantom voltage, or induced voltage, which would come from all the conductors running parallel to each other. The numbers you measured are extremely low (about 1/4 of a volt, a size AA battery is 1.5 volts). As Sirsparksalot said, the digital meters are extremely sensitive, and will pick up induced voltage in the wires. The low voltage reading sounds normal for this situation. As for the buzzing, I have experienced some breakers that are well seated and just make noise (internally), or it could be a loose connection. Are these the correct breakers for the panel? (just because they fit in the panel doesn't mean they were designed to be used in the panel) If you are comfortable with opening the panel box, I would pull the breakers out, and re-seat them, that perhaps could take care of the buzzing.
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Old 03-22-2013, 11:03 PM   #4
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Voltage on line that is turned off?


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Almost certainly it is phantom voltage, or induced voltage, which would come from all the conductors running parallel to each other. The numbers you measured are extremely low (about 1/4 of a volt, a size AA battery is 1.5 volts). As Sirsparksalot said, the digital meters are extremely sensitive, and will pick up induced voltage in the wires. The low voltage reading sounds normal for this situation. As for the buzzing, I have experienced some breakers that are well seated and just make noise (internally), or it could be a loose connection. Are these the correct breakers for the panel? (just because they fit in the panel doesn't mean they were designed to be used in the panel) If you are comfortable with opening the panel box, I would pull the breakers out, and re-seat them, that perhaps could take care of the buzzing.
the humming seems to be coming from the main breaker... yesterday it wasn't humming... the odd thing is how it starts quiet then builds then goes back down then repeats....

made sure all the breakers are seated fully, and they seem to be, all wires are in tight... all the breaker models match what the panel lists as acceptable breakers for this panel (its a GE powermark gold load center 200amp) every breaker is one of those half height breakers
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Old 03-22-2013, 11:10 PM   #5
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Voltage on line that is turned off?


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the humming seems to be coming from the main breaker... yesterday it wasn't humming... the odd thing is how it starts quiet then builds then goes back down then repeats....

made sure all the breakers are seated fully, and they seem to be, all wires are in tight... all the breaker models match what the panel lists as acceptable breakers for this panel (its a GE powermark gold load center 200amp) every breaker is one of those half height breakers
It sounds like you have covered all the bases... with all of today's electronic equipment, that could possibly account for the humming variation. Does the main breaker feel warm? It should be room temperature unless under very heavy load, or if there's a loose connection. I have an infrared temperature gun that has been invaluable for troubleshooting of this nature, but without one, it should not feel warm to the touch. From time to time I have heard buzzing noises from my panel, but that was several years ago and no problems have shown up, although I was never able to track down the cause of the noise. Haven't noticed it in several years. As long as all the connections are tight and none of the breakers are warm (or hot) to the touch, I don't think you have anything to worry about.
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Old 03-22-2013, 11:19 PM   #6
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Voltage on line that is turned off?


Phantom voltage due to cheap meter you are using. One of these http://www.lowes.com/Search=digital+...tal+multimeter will work better than what you are using. Personally, I prefer the Fluke, but the Ideal will work fine. Without going out and getting a new DMM/DVM, you need to place a load like a 60w incandescent lightbulb on the line in series between the hot & the Red lead, then check your readings again.
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Old 03-23-2013, 07:25 AM   #7
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Voltage on line that is turned off?


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Phantom voltage due to cheap meter you are using. One of these http://www.lowes.com/Search=digital+...tal+multimeter will work better than what you are using. Personally, I prefer the Fluke, but the Ideal will work fine. Without going out and getting a new DMM/DVM, you need to place a load like a 60w incandescent lightbulb on the line in series between the hot & the Red lead, then check your readings again.

http://www.testequipmentdepot.com/fl...FYid4AodXBMACA

that's the meter I am using, I sure hope that doesn't qualify as cheap
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Old 03-23-2013, 03:17 PM   #8
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Voltage on line that is turned off?


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Originally Posted by BlueBSH View Post
http://www.testequipmentdepot.com/fl...FYid4AodXBMACA

that's the meter I am using, I sure hope that doesn't qualify as cheap
Nope, one of the better. Just picking up inductance voltage from a line that is along the same run as that one, or in the same junction box.

Your fluke should not be picking up Phantom voltage with that model. What voltage range did you have it set for, when you were testing?
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Old 03-24-2013, 10:25 AM   #9
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Voltage on line that is turned off?


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Nope, one of the better. Just picking up inductance voltage from a line that is along the same run as that one, or in the same junction box.

Your fluke should not be picking up Phantom voltage with that model. What voltage range did you have it set for, when you were testing?
Was set up for auto ranging at the time, if I put it into a lower range manually I get the same results...

I just tried something different too... I put one lead on a ground that is grounded and the other lead on the other ground line that right now isn't connected and got 26.543v

Starting to wonder if my meter is going wacky
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Old 03-24-2013, 11:46 AM   #10
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Voltage on line that is turned off?


You can send it back to fluke to have it calibrated. What happens if you place a small candelabra in a base with the two leads, so you can use it to place some resistance on the line, then you should see the phantom voltage go away. You could also use a 16 Ohm resistor with some alligator leads, in place of a light bulb.
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Old 03-24-2013, 11:55 AM   #11
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Voltage on line that is turned off?


Change the battery

First you were reading millivolts, and not reading volts?.
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Old 03-24-2013, 12:50 PM   #12
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Voltage on line that is turned off?


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Change the battery

First you were reading millivolts, and not reading volts?.
yes it says V not mV
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Old 03-24-2013, 12:51 PM   #13
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Voltage on line that is turned off?


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Originally Posted by gregzoll View Post
You can send it back to fluke to have it calibrated. What happens if you place a small candelabra in a base with the two leads, so you can use it to place some resistance on the line, then you should see the phantom voltage go away. You could also use a 16 Ohm resistor with some alligator leads, in place of a light bulb.
if I put resistance in series I get 0.124v
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Old 03-24-2013, 01:39 PM   #14
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Voltage on line that is turned off?


Then I would not worry about it. I usually just place my meter in 200vAC to measure, not Auto-Ranging.

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