Amperage on Ground Wire

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Ondarc

Member
Location
New York
Ok so purely by accident while working on a buddies residential panel I found an errant amperage on his water pipe ground. It is only on the street side of the water meter, zero amps on the house side of the water meter. The amperage seems to range from .2 amps to 3 amps or so. It seems to runs up or down with the imbalanced load on the Neutral. The closer to the household load being balanced, the lower the amperage goes. The electrical service is brand new, a month or so old from the weather head down. Upon finding the issue I re tightened all of the connections in the new panel figuring that could be the issue. Nope. Household wiring is probably 80 percent new. There is some old knob and tube and old romex that will be going away as he renovates and so my first thought was bad neutral somewhere in the house. Shutting off the old circuits OR any new circuits, does not clear the problem, it only increases or decreases the amperage depending on the imbalance in load. I next disconnected both the ground from the water pipe and the ground rod expecting to find a voltage between ground and water service. I found zero volts between water pipe and ground wire and zero volts between ground rod and ground wire. Next I checked for voltage between Neutral and both grounds. Again zero volts. I then checked the water pipe with my clamp meter and as to be expected, found zero amps. Upon hooking the grounds back up, it's back. I then began turning off breakers, that is when I noticed it changing. As the house moves further out of balance, the greater the amperage to ground. I had him give the local utility a call, they came out, pulled his meter, and apparently plugged in a socket tester and told him the line up to the transformer was good. I'm stumped. Any help or insight that anyone can offer will be greatly appreciated. Thanks in advance, Dave.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
If you're referring to the Grounding Electrode Conductor (GEC) with a public metal water piping system some current on the GEC is normal.
 

MAC702

Senior Member
Location
Clark County, NV
Next call would be the water utility. If they don't like it, they may have more pull to the electrical utility to do something about it.

Are there neighbors with similar set-ups, perhaps even on the same transformer? Can you see what happens on theirs?

The really weird part, to me, is the zero amps on the house-side of the meter, but the current on the utility side being related to the electrical load at the house. How can we verify that zero current on the house-side? Is there anything else connected to the water meter itself?
 

KundaliniZero

Member
Location
CL
I think neutral and earth were joined and earth is not well connected to soil. So neutral=earth and when a load is connected and working so current is returning using the earth cable.

Enviado desde mi TA-1039 mediante Tapatalk
 

GoldDigger

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Location
Placerville, CA, USA
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Retired PV System Designer
In a typical residential neighborhood you have several houses connected to the same transformer secondary. Each house returns its own unbalanced current on its neutral wire.
But the POCO transformer secondary is also connected to an array of ground electrodes, so some of the current on your neutral will actually return over the parallel path through the grounded water pipes.
In addition, the water system effectively links all of the houses connected to it metallically so that there is a very low resistance path among their GES to neutral bond points. That means that some of your unbalance will actually go through the water pipe to your neighbor's neutral and back to the POCO transformer that way.
If a neutral anywhere gets compromised, then the water pipe connection to the neighbors' neutrals ends up carrying all the current. That is potentially dangerous.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
In a typical residential neighborhood you have several houses connected to the same transformer secondary. Each house returns its own unbalanced current on its neutral wire.
But the POCO transformer secondary is also connected to an array of ground electrodes, so some of the current on your neutral will actually return over the parallel path through the grounded water pipes.
In addition, the water system effectively links all of the houses connected to it metallically so that there is a very low resistance path among their GES to neutral bond points. That means that some of your unbalance will actually go through the water pipe to your neighbor's neutral and back to the POCO transformer that way.
If a neutral anywhere gets compromised, then the water pipe connection to the neighbors' neutrals ends up carrying all the current. That is potentially dangerous.


That's why it's normal to see a small amount of current on the GEC. :)
 

kwired

Electron manager
Location
NE Nebraska
Current takes all possible paths, if the metal water piping is a possible path then you should expect current to flow on it. How much current flows in a potential path depends on resistance of each possible path, but a metal water system that is continuous with no insulating joints and has multiple grounding electrodes tied to it throughout a neighborhood is possibly lower resistance then your service neutral conductor is.
 

Ondarc

Member
Location
New York
Thanks for all the replies guys. Much appreciated.



Next call would be the water utility. If they don't like it, they may have more pull to the electrical utility to do something about it.

Are there neighbors with similar set-ups, perhaps even on the same transformer? Can you see what happens on theirs?

The really weird part, to me, is the zero amps on the house-side of the meter, but the current on the utility side being related to the electrical load at the house. How can we verify that zero current on the house-side? Is there anything else connected to the water meter itself?

I have thought about calling the water department, I may. I checked the house side of the water meter with my Fluke clamp on, there is nothing else connected to the water service electrically that I can speak of. Whats weird to me is that there is zero amps to earth ground right outside of the house.



In a typical residential neighborhood you have several houses connected to the same transformer secondary. Each house returns its own unbalanced current on its neutral wire.
But the POCO transformer secondary is also connected to an array of ground electrodes, so some of the current on your neutral will actually return over the parallel path through the grounded water pipes.
In addition, the water system effectively links all of the houses connected to it metallically so that there is a very low resistance path among their GES to neutral bond points. That means that some of your unbalance will actually go through the water pipe to your neighbor's neutral and back to the POCO transformer that way.
If a neutral anywhere gets compromised, then the water pipe connection to the neighbors' neutrals ends up carrying all the current. That is potentially dangerous.



That's why it's normal to see a small amount of current on the GEC. :)


The potential for a dangerous situation with losing the Neutral is my main concern. I am suspicious of the line back to the Transformer and of the grounding at the transformer itself. I have never seen this before, then again I don't ever recall checking the GEC in a residential setting for amperage either, 3 amps on the GEC seems significant to me, but when the guys from the utility showed up, they apparently didn't seem worried. What would be considered a small amount?
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
The potential for a dangerous situation with losing the Neutral is my main concern. I am suspicious of the line back to the Transformer and of the grounding at the transformer itself. I have never seen this before, then again I don't ever recall checking the GEC in a residential setting for amperage either, 3 amps on the GEC seems significant to me, but when the guys from the utility showed up, they apparently didn't seem worried. What would be considered a small amount?

A lost neutral can reek havoc on electronics and other appliances if the voltage goes very high on a circuit(s) so in that instance it's probably better if the water pipe ends up carrying the neutral current when the neutral opens. I've seen drops from the pole where the neutral was lost and the house was operating normally. IMO 3 amps on the GEC is normal since it's a byproduct of how electrical systems are designed and are installed in accordance with the NEC.
 

ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC
.. IMO 3 amps on the GEC is normal since it's a byproduct of how electrical systems are designed and are installed in accordance with the NEC.
Could 3 amps also be normal for ground rods only, ABS/PVC water lines, plastic drain pipes, and no neighbors?

Or, must it take metallic water-service lines (regardless of plastic drains) to approach ~3 amp electrode returns, not just ground rods?
 

GoldDigger

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Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Could 3 amps also be normal for ground rods only, ABS/PVC water lines, plastic drain pipes, and no neighbors?

Or, must it take metallic water-service lines (regardless of plastic drains) to approach ~3 amp electrode returns, not just ground rods?
Three amps is probably high for a GES with a resistance of more than an ohm in parallel with a normally functioning neutral.
Especially since the OP measured close to zero volts with the GEC bond open.

Sent from my XT1585 using Tapatalk
 

kwired

Electron manager
Location
NE Nebraska
Could 3 amps also be normal for ground rods only, ABS/PVC water lines, plastic drain pipes, and no neighbors?

Or, must it take metallic water-service lines (regardless of plastic drains) to approach ~3 amp electrode returns, not just ground rods?
Ground rod will have higher resistance path back to the source, which will limit how much current it will carry. There will still be some current but it may be so low it is negligible.

The metal water pipe electrode can possibly be connected to multiple services in the neighborhood giving it a very low resistance path(s) back to the source. Some cases it may even be lower resistance then the service neutral, in which case it will carry more current then the service neutral does.
 

ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC
Three amps is probably high for a GES with a resistance of more than an ohm in parallel with a normally functioning neutral.
Especially since the OP measured close to zero volts with the GEC bond open.

Am I beginning to see the light of Ohms law, by Metering a lifted GEC to Neutral.

Current flowing on GES = Voltage / Resistance I=V/R
 

Ondarc

Member
Location
New York
Am I beginning to see the light of Ohms law, by Metering a lifted GEC to Neutral.

Current flowing on GES = Voltage / Resistance I=V/R


I was thinking the same way in terms of ohms law. The problem I have with that is the lack of voltage anywhere once the GEC is lifted and measured to the water service and ground rod. Neutral or GEC to water pipe ground = zero volts. Neutral or GEC to ground rod = zero volts. When re-connected, Amperage on section of ground wire to ground rod = zero amps. Amperage on section of water pipe on house side of water meter = zero amps. Amperages on street side of water meter OR GEC to street side of water meter range from .2A all the way to 3A depending on unbalanced load on the Neutral. It definitely makes sense though that the water piping may have a better return path considering that the house is several houses away the nearest transformer, the service drop from pole to house is well over 30 years old and the POCO did not want to change it when I did the service. It is just really strange to see anything on a ground wire when, as an electrician, we are trained to not want to see anything on the GEC.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Realize also that you could be measuring current coming from the neighbors house returning to the source on the water pipe>GEC>MBJ>service neutral.
 

Ondarc

Member
Location
New York
Realize also that you could be measuring current coming from the neighbors house returning to the source on the water pipe>GEC>MBJ>service neutral.


I definitely agree, also from an element on a neighbors electric hot water tank, I have read, can cause this. I would even think that could possibly be the case in this instance except that I can reduce the current to zero by opening the main. I would think that in opening the main breaker I would still see something coming in on the ground ? I'm still pretty much stumped in how to remedy this. I think he will have to live with it if the POCO doesn't get involved more.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I definitely agree, also from an element on a neighbors electric hot water tank, I have read, can cause this. I would even think that could possibly be the case in this instance except that I can reduce the current to zero by opening the main. I would think that in opening the main breaker I would still see something coming in on the ground ? I'm still pretty much stumped in how to remedy this. I think he will have to live with it if the POCO doesn't get involved more.

I can understand your concern but IMO you're concerned about nothing. As for living with it well there are millions of installations just like this that have current on the GEC without any problems. If you really want to solve the problem change the water pipe to plastic.
 

Ondarc

Member
Location
New York
Ha! He'd flip if I told him to have his water service redone lol. Anyways, thanks for all of the info and help guys. Greatly appreciated. :)
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I was thinking the same way in terms of ohms law. The problem I have with that is the lack of voltage anywhere once the GEC is lifted and measured to the water service and ground rod. Neutral or GEC to water pipe ground = zero volts. Neutral or GEC to ground rod = zero volts. When re-connected, Amperage on section of ground wire to ground rod = zero amps. Amperage on section of water pipe on house side of water meter = zero amps. Amperages on street side of water meter OR GEC to street side of water meter range from .2A all the way to 3A depending on unbalanced load on the Neutral. It definitely makes sense though that the water piping may have a better return path considering that the house is several houses away the nearest transformer, the service drop from pole to house is well over 30 years old and the POCO did not want to change it when I did the service. It is just really strange to see anything on a ground wire when, as an electrician, we are trained to not want to see anything on the GEC.
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?

With a common metal underground water piping system, and a common utility transformer, it would not be unusual to see 20% or more of the grounded conductor current flowing on the water pipe. As long as the service neutral is not compromised, there is not a serious shock hazard when a plumber disconnects the water pipe on the street side of your grounding electrode conductor connection. Often the water pipe is a good enough conductor that you will not see any symptoms of an open service neutral. The neutral current all flows on the water pipe. However that condition is a very dangerous one for the plumber. Many plumbing contractors have their guys install a temporary bonding jumper around the underground water pipe if they are cutting it.
 
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