Dumping 1.5 Amps to ground

I put a clamp on meter on the main cable from the meter into the panel and
noticed an imbalance (should read 0). Next, I checked the ground cable going
to a water pipe and found the same current flowing. I checked the pipe from
the ground clamp side to the house and the clamp to the water main and all
the current was heading to ground.
The houses on the street are delivered power from a low voltage bus on the
poles. What I mean is each house does not have its own transformer. There is
a transformer on every other pole that is connected to the LV bus line. I'm
thinking, imbalance current on the neutral line is getting carried back to
the transformer through the water line (city water system), back up
someone's ground to the transformer since the other houses are connected on
a different part of the bus. Does this make sense? Is that excessive
current? Should the utility check it?
Thanks
Reply to
SimonLW
Loading thread data ...
Power going to ground indicates to me that your electrical service may be improperly grounded, or loose connections, or improperly wired. If someone used the ground you describe as a neutral, ( grounded conductor ) you would have the same result.
I hesitate to even comment on the concept of the imbalance traveling back through the city water pipes to the utility. Usually there is no neutral feeding the distribution transformers. If there is a connection to the city water piping I would think it would be a mistake/accident. Neutral the grounded conductor is established at the electrical service. There may or may not be a ground at the transformer.
Does your electrical service have a ground rod, ufer, or some means of grounding besides the water pipe?
Anything happening on the customer side of the meter is yours. At least it is here. My suggestion is to hire a competent contractor to inspect/test the installation. I am betting that the issue is on your side of the meter and has nothing to do with the distribution. Let us know what you find.
Reply to
SQLit
Where are you located? That will help answer your question.
Charles Perry P.E.
Reply to
Charles Perry
|
|>I put a clamp on meter on the main cable from the meter into the panel and |> noticed an imbalance (should read 0). Next, I checked the ground cable |> going |> to a water pipe and found the same current flowing. I checked the pipe |> from |> the ground clamp side to the house and the clamp to the water main and all |> the current was heading to ground. |> |> The houses on the street are delivered power from a low voltage bus on the |> poles. What I mean is each house does not have its own transformer. There |> is |> a transformer on every other pole that is connected to the LV bus line. |> I'm |> thinking, imbalance current on the neutral line is getting carried back to |> the transformer through the water line (city water system), back up |> someone's ground to the transformer since the other houses are connected |> on |> a different part of the bus. Does this make sense? Is that excessive |> current? Should the utility check it? |> Thanks | | Where are you located? That will help answer your question. | | Charles Perry P.E.
His NNTP posting IP address suggests in or around the Dayton Ohio area.
Reply to
phil-news-nospam
| I put a clamp on meter on the main cable from the meter into the panel and | noticed an imbalance (should read 0). Next, I checked the ground cable going | to a water pipe and found the same current flowing. I checked the pipe from | the ground clamp side to the house and the clamp to the water main and all | the current was heading to ground. | | The houses on the street are delivered power from a low voltage bus on the | poles. What I mean is each house does not have its own transformer. There is | a transformer on every other pole that is connected to the LV bus line. I'm | thinking, imbalance current on the neutral line is getting carried back to | the transformer through the water line (city water system), back up | someone's ground to the transformer since the other houses are connected on | a different part of the bus. Does this make sense? Is that excessive | current? Should the utility check it? | Thanks
Scenario 1:
There should be a connection between the neutral on the bus wires between the poles, and the transformer neutral terminal, as well as a ground wire to earth at the pole the transformer is on. If the connection between the bus and the transformer is broken, then the only return path for imbalance current is through earth. Since every house should have the neutral that comes off the pole grounded, each one of those serves as a parallel path through earth back to the earth ground wire at the transformer.
Scenario 2:
A neighbor has a broken or loose neutral in their service drop, but their neutral in the panel is still grounded (perhaps through the water pipe). Their current imbalance is flowing out the earth ground (maybe water pipe) and using parallel paths back to the transformer, some through the ground wire at the transformer, and some through each neighbor (and you) entering via the ground and going back up the service drop to the transformer.
Scenario 2B:
Same as scenrio 2, but you are the one with the broken or loose neutral in the service drop.
Scenario 3:
The neutral wire of the medium voltage distribution circuit connected to the transformer primary is typically connected to the secondary neutral, and both connected to ground. Thus, there is a metallic path between your neutral wire and the neutral of the medium voltage distribution wires. If there is a broken neutral between the transformer primary and the distribution, either at the transformer, or further down the line, then the primary current trying to return to the upstream source will flow through the ground wire on the pole, and find parallel paths back to the source. In the simplest case, the neutral is broken at that transformer, and each service drop, plus the pole ground, are parallel paths through earth to other service drops of houses on other transformers with OK neutrals, providing a working return path. At medium voltages, typical earth resistances divided by all these parallel paths can still result in a working system with little voltage drop.
Reply to
phil-news-nospam
???? Most distribution transformers in the US are fed from line to neutral, not line to line.
Charles Perry P.E.
Reply to
Charles Perry
I shut off the main breaker and checked current through the ground lead. The current dropped a little, but is still considerable, 1 amp. There is another ground line that runs out to a ground rod. It looks properly connected, but shows no current flow.
Since any conductor has resistance, there is a voltage drop across the neutral line. This means the voltage on the neutral can be slightly different between me an my neighbor's house if the neutral bus is carrying a significant load. Since the neutral is bonded to the water line in each of our houses, any potential difference on the neutrals between our houses will be conducted through the metallic water supply line. There could be other reasons, but considering the system has no faults, this is the best theory I have. -S
Reply to
SimonLW
I shut off the main breaker and checked current through the ground lead. The current dropped a little, but is still considerable, 1 amp. There is another ground line that runs out to a ground rod. It looks properly connected, but shows no current flow.
Since any conductor has resistance, there is a voltage drop across the neutral line. This means the voltage on the neutral can be slightly different between me an my neighbor's house if the neutral bus is carrying a significant load. Since the neutral is bonded to the water line in each of our houses, any potential difference on the neutrals between our houses will be conducted through the metallic water supply line. There could be other reasons, but considering the system has no faults, this is the best theory I have. -S
Reply to
SimonLW
| I shut off the main breaker and checked current through the ground lead. | The current dropped a little, but is still considerable, 1 amp. There is | another ground line that runs out to a ground rod. It looks properly | connected, but shows no current flow.
That suggests the broken neutral is on the pole between the LV bus and the transformer. The transformer neutral is still connected to ground and the bus is getting back to the transformer via each service drop's ground electrode.
Reply to
phil-news-nospam
| | | I shut off the main breaker and checked current through the ground lead. | | The current dropped a little, but is still considerable, 1 amp. There is | | another ground line that runs out to a ground rod. It looks properly | | connected, but shows no current flow. | | That suggests the broken neutral is on the pole between the LV bus and | the transformer. The transformer neutral is still connected to ground | and the bus is getting back to the transformer via each service drop's | ground electrode.
Let me add that the transformer neutral would still be grounded even if the ground wire on the pole itself is broken as part of the neutral being broken. Since the neutral is connected between secondary and primary, the return path to the transformer can very well be through earth to other secondary systems (neighbors down the road on a different transformer) and run back through the neutral wire of the primary lines.
There is an old saying "electricity takes the path of least resistance". That's not true. The correct statement would be "electricity takes all paths in parallel in proportion to the inverse of resistance of each path".
Reply to
phil-news-nospam
Since the current through the water pipe is 1 amp but the current through the ground rod is nil, I would have guessed that someone else's house has a broken neutral, and its neutral current is going through their water pipe ground, through the water piping, the O/P's water pipe ground and through the O/P's neutral back to the transformer. And the other ground is poor.
To the O/P: Does the current vary on its own even when you don't switch anything on/off yourself? Also, if you switch a large 120V load (space heater or something) on and off does the current change by the current drawn by the device (rated wattage divided by 120) ? Experiment with plugging it into outlets using different hot legs if possible.
Reply to
Michael Moroney
| snipped-for-privacy@ipal.net writes: | |>| |>| I shut off the main breaker and checked current through the ground lead. |>| The current dropped a little, but is still considerable, 1 amp. There is |>| another ground line that runs out to a ground rod. It looks properly |>| connected, but shows no current flow. | |>That suggests the broken neutral is on the pole between the LV bus and |>the transformer. The transformer neutral is still connected to ground |>and the bus is getting back to the transformer via each service drop's |>ground electrode. | | Since the current through the water pipe is 1 amp but the current through | the ground rod is nil, I would have guessed that someone else's house | has a broken neutral, and its neutral current is going through their | water pipe ground, through the water piping, the O/P's water pipe ground | and through the O/P's neutral back to the transformer. And the other | ground is poor.
That could very well be. As the pipe is likely metallic all the way, it would be a good path between neighbors.
But the water pipe can also have a lot lower impedance to earth than a single electrode, too, especially if it is leaking a slight amount.
Reply to
phil-news-nospam

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.