Amperage on Ground Wire

[Ondarc]

Not sure how you can drive current with zero volts. When you measure between the neutral and the water pipe, you should be reading the voltage drop on the service neutral between where you are connected to the neutral and the other point where the water pipe is connected to the neutral to the transformer that supplies your service.

Was there any current on the neutral when you took that voltage measurement?

Having zero volts baffles me as well. There was current on the Neutral during that reading though, I don't remember how much exactly. The reading was taken under normal circumstances, I did not turn anything off.

 

[kwired]

Having zero volts baffles me as well. There was current on the Neutral during that reading though, I don't remember how much exactly. The reading was taken under normal circumstances, I did not turn anything off.

.01 volts is still greater then zero - what kind of resolution and accuracy was your meter?

The higher the neutral current the higher that measured voltage will be because voltage drop on that neutral conductor will increase as current increases, so when you have pretty low neutral current to begin with the more it will look like zero volts if you don't have sensitive enough measuring equipment. If you have an aux ground rod or CEE in the vicinity and it is still connected when measuring that will also help bring the two closer together if you are measuring to "ground" in the local vicinity.

 

[don_resqcapt19]

.01 volts is still greater then zero - what kind of resolution and accuracy was your meter?

The higher the neutral current the higher that measured voltage will be because voltage drop on that neutral conductor will increase as current increases, so when you have pretty low neutral current to begin with the more it will look like zero volts if you don't have sensitive enough measuring equipment. If you have an aux ground rod or CEE in the vicinity and it is still connected when measuring that will also help bring the two closer together if you are measuring to "ground" in the local vicinity.

Good points. He could try a measurement to remote earth. That is earth at least 50' from any type of grounding electrode. Just short rod in the round and a long wire will work.

 

[Ondarc]

.01 volts is still greater then zero - what kind of resolution and accuracy was your meter?

The higher the neutral current the higher that measured voltage will be because voltage drop on that neutral conductor will increase as current increases, so when you have pretty low neutral current to begin with the more it will look like zero volts if you don't have sensitive enough measuring equipment. If you have an aux ground rod or CEE in the vicinity and it is still connected when measuring that will also help bring the two closer together if you are measuring to "ground" in the local vicinity.

I have been thinking of trying a different meter. I used an older Fluke clamp-on that I typically use for side work. My daily meter at work is a Fluke 374 clamp-on. When I go back to his house this weekend, Ill be sure to add some load and measure again with the newer meter, maybe something will show.

 

[Ondarc]

Good points. He could try a measurement to remote earth. That is earth at least 50' from any type of grounding electrode. Just short rod in the round and a long wire will work.

In order to increase the likelihood of detecting a lower voltage?

 

[don_resqcapt19]

In order to increase the likelihood of detecting a lower voltage?

That would just give you a voltage reference to earth, but after thinking about it some more that voltage isn't important. There has to be voltage between the neutral and the water pipe if current flows.

 

[kwired]

That would just give you a voltage reference to earth, but after thinking about it some more that voltage isn't important. There has to be voltage between the neutral and the water pipe if current flows.

But the water pipe is bringing you a reference from further away, but any nearby bonding or even nearby connected electrodes will change what you measure.

Ever measure different currents on conductors in parallel? If they are exact same resistance they should carry same current, even a small difference in length of each conductor changes resistance enough you will throw current balance between them off.

 

[don_resqcapt19]

But the water pipe is bringing you a reference from further away, but any nearby bonding or even nearby connected electrodes will change what you measure.

Ever measure different currents on conductors in parallel? If they are exact same resistance they should carry same current, even a small difference in length of each conductor changes resistance enough you will throw current balance between them off.

But I need voltage to drive the current. A digital meter should be able to resolve that voltage.

With two sets of conductors in parallel, the change in current will change with the same percentage as the change in length, if everything else is exactly the same.