Weird Voltage readings-I need advice

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Old 03-18-17, 07:36 PM
J
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Weird Voltage readings-I need advice

Ok so this is my ongoing new construction. I was testing my electrical circuits today before I start drywall installation. I have full power hooked to my service panel. Utilizing a single breaker I tested all home runs individually by inserting each home run hot into the breaker. All the neutrals are fully connected at the panel and at each recepticle. Same for all grounds. Everything checked out great except for 2 circuits. Both of these circuits will eventually be arc fault breakers. So as I was checking voltages I inadvertently forgot that the neutrals for both of these circuits were not connected to the neutral bar. However when used my volt meter from hot (black) to neutral I got a 101v reading. And consequently when I went from hot to ground of course I got 125v. Since there is absolutely nothing else on either of these separate circuits-how is it possible that I read 101v on a non connected neutral. This one is making me nuts.
Thanks for any advice.
Jim
 
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Old 03-18-17, 07:52 PM
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If you were using a digital meter... it is sensitive enough to pick up ghost readings.

A ghost reading is where a live wire runs next to a dead one and the voltage from the live one can partially be induced onto the dead wire.

This can happen on an unconnected wire...... not a connected neutral.

If you were to connect a light bulb across those wires you would read 0v between the wires and the bulb would not light.
 
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Old 03-18-17, 11:31 PM
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Thanks for your help pjmax. I'm going o be thinking about this one for a long time I think...
 
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Old 03-19-17, 12:54 AM
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Get a cheap analog multimeter and you won't have that problem.
 
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Old 03-22-17, 01:20 PM
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Start with what capacitive reactance is and how it works when in series with your meter resistance.
 
 

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