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#1
03-22-14, 04:11 PM
Member
Join Date: Nov 2013
Posts: 304

How come my non-contact volt reader doesn't pick up return voltage.. for example if I have 100w of light going, shouldn't I be getting indication of the 100w going back to the panel?

Or if I used a multimeter, shouldn't I be getting a voltage reading neutral to ground for any loads on that circuit?

Thanks for bearing with my lame questions...

#2
03-22-14, 04:40 PM
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'Cause it is return "current", not voltage.

#3
03-22-14, 05:11 PM
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Join Date: Nov 2013
Posts: 304
I told you I had lame questions.

So if I have an ampmeter I can measure on the neutral to ground no matter the size of load on that circuit? And say "current" was leaking to ground, I would be able to pick this up with an ampmeter?

Just trying to guage what the next tool I might be buying!

#4
03-22-14, 05:32 PM
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Join Date: Mar 2010
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If you have an ammeter you can measure current flowing from neutral to ground but what you are measuring is current flowing on a specific wire namely that which you clamped the (noncontact) ammeter probe on. Normally there is no current flowing between neutral and ground up in the house so you should measure zero amperes on the ground wire from a receptacle back to the panel.

You may not measure "just any amount" of current; the meter has its limits as to how many amperes may be measured.

Voltage is always measured between two points (of your choice). For example if you measured voltage between the hot and neutral prongs of a live receptacle then you should measure approximately 120 volts.

Measuring between neutral and ground at a receptacle up in the house may give you a positive reading (probably not more than 2 volts) if that circuit is being used heavily. Current flowing normally back to the panel via the neutral together with the less than perfect conductivity of the neutral wire (there's a tiny bit of resistance) results in a voltage drop or voltage difference between the receptacle and the panel. Your voltage measurement includes the voltage drop on the ground wire coming up from the panel where incidentally neutral and ground are tied together. Wit no current normally flowing on the ground wire, this voltage difference is zero. Adding the voltage drops for this round trip worth of wiring, we may get a volt or two total.

#5
03-22-14, 05:40 PM
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Join Date: Nov 2013
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Would you be able to measure "current" on the grounded water pipe or lightning rod of your electrical service?

#6
03-22-14, 05:48 PM
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Current should not be flowing on either of those items.

#7
03-22-14, 05:49 PM
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Would you be able to measure "current" on the grounded water pipe or lightning rod of your electrical service?
There should be nothing there to measure. (unless you've lost your neutral connection to the pole)