.2 volts between neutral and ground

If there is enough current flowing through the circuit to develop the .1 to .2 volts across the neutral wire, then this is a normal reading. To simply things you could just measure from neutral to ground.

For a real-world example, consider a single 100W light bulb, 65 feet from the breaker panel. 12 gauge wire has about .0019 ohms per foot. So with the drawing .833 amps and 65 feet of wire, one could expect .1 volt drop in the neutral line. So your measured numbers of .1 to .2 volts are very reasonable. With a heavy load you could see 1 to 2 volts.

Geo.

You are measuring the voltage drop on the neutral wire from an outlet, back to the breaker box. Do you understand Ohm's law?

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

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David William Botsch
dwb7@cornell.edu
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Wouldn't that be from one wire on the outlet, back to breaker box, then back over the other wire back to the outlet?

So, it sounds like there is more current >

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David William Botsch
dwb7@cornell.edu
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Dave Botsch ha escrito:

The readings you are obtaining are normal. The neutral wire carries the current of the circuit back to the breaker box, while the ground conductor is unloaded. The load in the neutral causes a slight voltage drop in the conductor, and your reading is just showing that.

If you measured a difference of 1 - 3 volts between neutral and ground, you should worry, but a 0.20 V difference is meaningless. Probably there isn=B4t even a difference and you are just obtaining an spurious reading caused by the DMM itself.

Draw a picture showing three wires going from the outlet back to the fuse box. There is the hot lead, usually black wire, the return or neutral lead, usually white wire, and the safety ground which connects to the outlet box and the outlet grounding pin. Connect the safety ground and the return/neutral lead together at the fuse/circuit breaker box. Now have a 1-ampere current flowing between the hot lead and the return/neutral lead. The current flowing back to the fuse box will have the voltage drop the previous poster described. When you connect a voltmeter between the safety ground and the return/neutral point at the outlet you see the drop in the return wire.

H> Wouldn't that be from one wire on the outlet, back to breaker box, then

What you are reading is normal. The heavier the load, the greater the reading. You are seeing the differential voltage difference between the load return side and the neutral side. The wiring has some electrical resistance, and you are measuring this along the neutral to ground return path.

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JANA _____

In the past, I hadn't noted any voltage btwn neutral and ground and hot to neutral and hot to grnd was the same (it's off, now, by the amounts above).

I'm guessing this is bad and is something I should have looked into as soon as possible?

I am going to check again tonight after people have gone to bed and electric usage in the area should have gone down.

thoughts?

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******************************** David William Botsch snipped-for-privacy@cornell.edu ********************************

Dave Botsch wrote: > So, it's much more complicated, then, than the neutral and ground are > connected together at the breaker panel, thereby equalizing the > potential between the two, so, there shouldn't be a voltage differential > between the two (this only works if it's the same wire, same current, and > same length run)? And that the voltage between hot and neutral and hot and > ground should be the same because of that? >

Please Dave, tell me you're not an EE professor. As others have said,

200mV is completely normal for a modest load. I'm always amazed when people discover there is a voltage drop (courtesy of Mr Ohm) on BOTH wires supplying the load. Run a hair dryer on that circuit and measure the drop again. If it stays low (

At the breaker panel their potential is equal. But as you go farther from the panel, your "neutral" wire is not at the same potential as the neutral in the panel because of the load current and resistance of the wire. The ground wire never has current flowing though it under non-fault conditions, so what you measure on any ground wire is the potential of the neutral / ground bus at the panel.

Geo.

You have to remember that there is not supposed to be any current flow in the safety ground, so it will have the same voltage as the ground buss bar in your breaker box. So, when you connect the meter between neutral and ground, you are measuring the voltage drop on the neutral conductor, only. The higher the load on that circuit, whether at that outlet, or another will show on your meter. Your meter should have a 10 Megohm input impedance, so the ohm or so resistance of the ground wire won't affect the reading.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Haha, no, I'm not (actually, I'm not a professor at all).

Believe it or not, a lot of the > Dave Botsch wrote:

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********************************
David William Botsch
dwb7@cornell.edu
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