.8 amps/Dangerous?

P

pauld

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Location
atl,ga
What are thoughts on this reading? Ran into this on a building today should be addressed immediately. I would hate to alarm the customer if not necessary.
 

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what are we looking at here? amperage on a grounding electrode?

if so, you need to understand that electricity takes ALL PATHS AVAILABLE. not the misinformation that we've all heard about taking the path of least resistance.

so, on any system, there will be current flow on the GEC. it just dpeneds upon how low the resistance on the grounding electrode system is, versus what the resistance is on the service grounded conductor. this COULD be an indicator of a system neutral getting weak, but not neccessarily. what is the amperage on the neutral to compare to?
 
IMHO I'd ask a few questions before declaring this perfectly normal.

1) Are we looking at current flowing to water pipe bond, to a couple of ground rods, or to something else?

2) How large of a service are we looking at?

If I saw 0.8A flowing into a typical ground rod at a residence, I'd want to dig further. That current would imply significant voltage on the neutral given the typical ground rod resistance.

If I saw 0.8A flowing into to a water pipe ground in an urban residence (where common underground piping is typical) then I wouldn't be concerned at all; the underground pipes are a metallic connection parallel to the neutral.

If I saw 0.8A flowing to a water pipe bond at a location where the underground water piping was insulated, I'd be very concerned; that 0.8A implies some sort of ground fault in the facility.

If I saw 0.8A flowing to a large grounding electrode system at a big industrial plant with a huge service I wouldn't be concerned at all.

(And note: I am familiar with theory and the above is based on that. I am not a professional electrician.)
 
electrofelon said:
I was just going to post the same thing, seems low actually.
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I agree. I did a little experiment on my own water pipe. Test clamp has a conversion of 1mA/A. First test indicated about .33 amps with the normal house load and the clamp directly around the pipe where it exits the foundation. Then I turned on a heat gun with a 120 volt load of about an 8.5 amps and the current on the pipe shot up to .89 amps.

You mathematicians can probably estimate about how much of the current is flowing on the pipe under normal conditions.


Water Pipe Current 002.jpgWater Pipe Current.jpg
 
Exactly. There are very common situations where multiple amps on a GEC is totally expected and a normal consequence of the system design. The issue of current on underground water systems is not a problem until a plumber needs to cut the pipe.

This is why I'd hope the OP comes back and describes exactly what line they are measuring. I agree with @infinity and @electrofelon that based on the picture this is probably a nothing burger, but would like to know more.
 
infinity said:
I agree. I did a little experiment on my own water pipe. Test clamp has a conversion of 1mA/A. First test indicated about .33 amps with the normal house load and the clamp directly around the pipe where it exits the foundation. Then I turned on a heat gun with a 120 volt load of about an 8.5 amps and the current on the pipe shot up to .89 amps.

You mathematicians can probably estimate about how much of the current is flowing on the pipe under normal conditions.


View attachment 2582316View attachment 2582317
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If I am reading that right it appears to say 'mA' so 0.33 mA = 0.33 / 1000 A = 0.00033 Amps
 
tortuga said:
If I am reading that right it appears to say 'mA' so 0.33 mA = 0.33 / 1000 A = 0.00033 Amps
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I mentioned in post #9 that the clamp has a 1 mA to 1 amp conversion factor. Here's a test photo where I tested the meter first with a heat gun. 8.52 mA = 8.7 amps. There's an obvious small margin of error with one or both of the measurements.

IMG_20260313_102026504.jpg
Low setting on gun.
IMG_20260313_102002815.jpg
 
infinity said:
First test indicated about .33 amps with the normal house load and the clamp directly around the pipe where it exits the foundation. Then I turned on a heat gun with a 120 volt load of about an 8.5 amps and the current on the pipe shot up to .89 amps.
Click to expand...
So that's a delta of either 1.22A or of 0.56A, depending on sign (you could do the test twice, with the 120V load on each of the two legs, to differentiate). Which says that the GEC path has an impedance in ratio to the intended grounded conductor path of either (8.5-1.22)/1.22 = 6.0 or (8.5 - 0.56) / 0.56 = 14.

Cheers, Wayne
 
wwhitney said:
So that's a delta of either 1.22A or of 0.56A, depending on sign (you could do the test twice, with the 120V load on each of the two legs, to differentiate). Which says that the GEC path has an impedance in ratio to the intended grounded conductor path of either (8.5-1.22)/1.22 = 6.0 or (8.5 - 0.56) / 0.56 = 14.

Cheers, Wayne
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I see thanks I figured I missed something so @wwhitney you're saying the added test current on the pipe could be the same direction as the original pipe current or the opposite direction from the original pipe current? And there might be base current from the pipe to the neutral bar -.33A or current from the neutral bar to the pipe +.33A ?
And if thats correct @infinity could take a 2nd measurement of his total service neutral current at the same time as both readings;
If the pipe got 0.56 A of that, then the neutral total got about:
8.5 - 0.56 = 7.94 A

Or If the pipe got 1.22 A of that, then the neutral total got about:
8.5 - 1.22 = 7.28 A
 
tortuga said:
I see thanks I figured I missed something so @wwhitney you're saying the added test current on the pipe could be the same direction as the original pipe current or the opposite direction from the original pipe current?
Click to expand...
Let's say that if the only load is from L1 to N, then the neutral current is positive, while if the only load is from L2 to N, then the neutral current is negative. The meter only gives you the magnitude of the current, without the sign. You can think of positive and negative as from/to, although this is AC.

If the neutral current can only return on the grounded service conductor or the water pipe, no 3rd option, then there's two possibilities for infinity's measurements of the current on the water pipe:

Both the 0.33 and the 0.89 have the same sign. So the change is 0.56A, out 8.5A of new load. That means the resistance ratio is (8.5-0.56)/0.56 = 14. If we had measured grounded service conductor current at the same time as the water pipe, it would have read 14 * 0.33 = 4.7A and 14 * 0.89 = 12.6A, respectively.

Or the 0.33 and 0.89 have different signs. So the change is 1.22A, our of 8.5A of new load. That means the resistance ratio is (8.5-1.22)/1.22 = 6.0. If we had measured grounded service conductor current at the same time as the water pipe, it would have read 6.0 * 0.33 = 2.0A and 6.0 * 0.89 = 5.3A, respectively.

tortuga said:
If the pipe got 0.56 A of that, then the neutral total got about:
8.5 - 0.56 = 7.94 A

Or If the pipe got 1.22 A of that, then the neutral total got about:
8.5 - 1.22 = 7.28 A
Click to expand...
Yes, but in the first case, the 7.94A is the difference of the two service neutral current measurements (12.6 - 4.7 in the above), while in the second case, the 7.28A is the sum of the two service neutral current measurements (5.3 + 2.0 in the above), because the meter is only giving us magnitude and not sign.

Cheers, Wayne
 
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