[terps530]

Hello All,
First Time Poster- I am so glad I found this forum today. I've read through several threads and there seems to be tons of great info, but I wanted to get a little bit specific on my issue and see what some of you think. I am a mechanical engineer so I have some electrical background (changed switches/outlets etc and understand basic wiring), but I'm not too comfortable messing with the panel yet etc.

Here is the kinda brief version, and then if you want the details, you can read the rest:
My water pipe main in (from the street to my basement), has had pinhole leaks 6 times in the 2.5 years since I've moved into my townhouse. 20 year old construction, no one else in the 200 units has had this happen once to their pipes. Water company thought it could be electrical related, so we tested last year and there was stray current in the earth.

I've borrowed a clamp meter and there is current that is on my water pipe (right where it exits the basement). When the furnace (forced hot air) kicks on, I get about a 1.2A spike on the pipe. When I plug in an appliance and it's pulling a load, the current is directly additive on the waterpipe. I thought it was a specific outlet, but I plugged a vacuum in about 10 different outlets in the house, and every time I see a spike of about 1.5A on the water pipe when it turns on.
The ground wire that is clamped to the water pipe was loose, and has been since tightened, but still the current goes all on the water pipe and none on the ground wire.

I've had an electrician check my panel and he said everything looked good there. Tightened everything up etc. We thought it was a neutral touching a ground wire somewhere in an outlet, but when it happens for every outlet, we thought it would be a faulty neutral return (from my panel to the transformer across the street. Wiring is underground. Had Con Edison (my electric provider) check it out and I replicated the issue for them, they did some tests and had said it was a faulty neutral so they put a shunt up while they waited to do permanent repairs (said they were going to dig and fix). Now, they tell me it's fixed, but they did no digging.

Current still exists on the water pipe when either the furnace goes on, or when I plug in anything.

a) What is going on?! How do I fix this??
b) If the ground is constantly taking current, does that make sense that it could act as a catalyst to cause the copper pipes to corrode, and thus keep getting pinhole breaks? FYI I had 3 in December this year, and that kind of kicked this into high gear. I had thought that A/C current shouldn't cause corrosion- only DC. Or is it possible that voltage is arcing to the pipe and causing a sudden pinhole break?
//////////////

Some more details:
We know the water pipe gets a leak when I hear a hissing noise in the basement. I currently have a leak but the town is waiting to dig it up until I get this electrical issue fixed. They want to install a dielectric union on the water pipe between their main and my pipe. This makes me nervous because Con Edison told me our zone is coded so that the water pipe is the primary ground. So they would break this path, and thus where would my ground go? The electrician said he could put in 2 more ground rods to make sure that I have a strong ground in place if they do this. I think this is a good idea, but is more a safety backup rather than fixing the problem.

The leaks always seem to show up when it gets cold out, but I don't think they are caused by freezing (since they are 4ft underground). My thoughts are that the furnace circuit is somehow bad and once that starts turning on, it accelerates the process, or starts creating that constant current on the water pipe, and maybe this stresses it till it pops.

I have replaced switches/outlets in the townhouse, as well as a few light fixtures, but I'm pretty positive I know what I'm doing and wired everything correctly. Pretty much one at a time, and just copy the previous wiring. I also do not think I caused this because i found out it happened before I moved in. Also all the lights/switches work, and I used a polarity tester and never showed anything flipped etc. Also there never is any dim/flickering lights or weird situations where the power seems not to be full.

I tried to isolate the circuit by testing different combinations on the breaker. That is how I found out the when the heat goes on, the current always spikes. I also so that when the drier was on, I get a spike, which then led me to test many appliances. Pretty much when anything goes on or is plugged in, and is pulling a load, that amperage shows up on the water pipe.
I've spoken to some EEs at work who I consider very smart. They say most likely that somewhere the neutral is bleeding to ground.

How can I tell if this is Con Edisons responsibility (bad neutral on their side), or if it is on my side somewhere.

Hypothetically if a light fixture wire nut wasn't tight and the neutral was touching the ground somewhere, could that be the cause of this? I thought only that circuit would show the effects of the current bleed onto the ground, or are all the neutrals tied together before the panel somewhere? I'm trying to figure out how every one of my outlets in the house causes current to go on the ground. There is no way they all are wired incorrectly.


I know it's long winded, but this has been quite a stumper. The electrician thought it was a bad neutral on Con Edison's side, but I don't know if he was being lazy and didn't check something on my side. I am capable of checking every switch/outlet in the house to find the problem, but I'd love to avoid that if I don't have to as it will be time consuming and annoying with some fixtures.

Thanks a ton in advance, and looking forward to any help/insight you can share.
-Dan

 

[AllanJ]

All of the neutrals for all of the branch circuits are tied together in the panel, together with the fat copper wire (grounding electrode conductor) to the cold water pipe and the main neutral in the feed (service conductors) from the utility pole.

The current flowing through your home wiring seeks to return to the pole transformer where it came from.

There are two ways from the panel back to the pole transformer, one via the neutral in the service wires and the other via the water pipe and the earth.

There are ground rods on some if not all of the utility poles. These are connected to the transformer neutral using a shared neutral/ground wire about halfway up the utility pole. The path from your water pipe (or your ground rod) through the dirt (earth; ground) has much more resistance than the neutral wire in your service drop. So only a small amount of current, perhaps just a few milliamperes, will return to the transformer via the pipe and the earth when the neutral in the service drop is in place and in good condition.

 

[Jump-start]

Ok, I will type up a longer post but in a nut shell some current on a water pipe is normal however after some point it indicates a poor or open neutral connection.

How much current is normal depends on many things.

For starters, how many amps is the service? Is this over head or underground? How far away is the transformer from the house (if you know)?

Edit: You can test for an open neutral by turning off all breakers on the A or B phase but not both in addition to 240 volt loads. Plug in some space heaters and turn on lights across different circuits on the breakers that are on.

Next, measure the current on the incoming neutral vs the water pipe. If the difference is large such as more than 10% on the water bond vs the neutral something could be wrong. If more current is on the water bond then you defiantly have an open neutral.

Next, to rule out a neighbor problem trip the main breaker. With the main tripped measure the current on the neutral and water pipe. If you have more than an amp or more than a few amps something is wrong with a neighbor's neutral or a neutral out on the line.

 

[terps530]

All of the neutrals for all of the branch circuits are tied together in the panel, together with the fat copper wire (grounding electrode conductor) to the cold water pipe and the main neutral in the feed (service conductors) from the utility pole.

The current flowing through your home wiring seeks to return to the pole transformer where it came from.

There are two ways from the panel back to the pole transformer, one via the neutral in the service wires and the other via the water pipe and the earth.

There are ground rods on some if not all of the utility poles. These are connected to the transformer neutral using a shared neutral/ground wire about halfway up the utility pole. The path from your water pipe (or your ground rod) through the dirt (earth; ground) has much more resistance than the neutral wire in your service drop. So only a small amount of current, perhaps just a few milliamperes, will return to the transformer via the pipe and the earth when the neutral in the service drop is in place and in good condition.

Thank you Allan. That is what I want to tell the electric provider. A few weeks back when they were on site and determined there was a 'bad neutral'. They had flags and spray paint all over my grass to trace the line, and were supposed to dig and fix it. They arrived one morning and I went to work, and when I came back, nothing was dug up. A neighbor said they saw them sit in the truck for a few hours- then get out and walk around near some electrical access point, but definitely did not dig. Now they tell me it is fix, but they won't reveal to me what they actually did to fix it, or what the problem was in the first place...

I want to call them out and claim that the neutral is still bad and I have X, Y, and Z data to back it up. When the coffee maker, heat, toaster, and vacuum are all on, I had over 7 amps on the water pipe. I'm no expert but I believe this is very unsafe, because if anything interrupts that ground path on the water pipe, I could get major zapped touching a faucet who knows what.

Is it possible that they push back to say that my wiring is causing this? I don't see how that can be based on some of the things you and others have said, but that's why I'm here for help.

I have a picture of my water pipe in the basement, but it's not letting me post links/images yet.

Thanks

 

[Jump-start]

Thank you Allan. That is what I want to tell the electric provider. A few weeks back when they were on site and determined there was a 'bad neutral'. They had flags and spray paint all over my grass to trace the line, and were supposed to dig and fix it. They arrived one morning and I went to work, and when I came back, nothing was dug up. A neighbor said they saw them sit in the truck for a few hours- then get out and walk around near some electrical access point, but definitely did not dig. Now they tell me it is fix, but they won't reveal to me what they actually did to fix it, or what the problem was in the first place...

I want to call them out and claim that the neutral is still bad and I have X, Y, and Z data to back it up. When the coffee maker, heat, toaster, and vacuum are all on, I had over 7 amps on the water pipe. I'm no expert but I believe this is very unsafe, because if anything interrupts that ground path on the water pipe, I could get major zapped touching a faucet who knows what.

Is it possible that they push back to say that my wiring is causing this? I don't see how that can be based on some of the things you and others have said, but that's why I'm here for help.

I have a picture of my water pipe in the basement, but it's not letting me post links/images yet.

Thanks

In addition to a fire. Excellent questions!

7 amps is high, you do have a problem. Pictures of the main panel can help too. If I am not mistaken I believe you have to be over a certain number of posts to upload images.

 

[brric]

Ok, I will type up a longer post but in a nut shell some current on a water pipe is normal however after some point it indicates a poor or open neutral connection.

How much current is normal depends on many things.

For starters, how many amps is the service? Is this over head or underground? How far away is the transformer from the house (if you know)?

Edit: You can test for an open neutral by turning off all breakers on the A or B phase but not both in addition to 240 volt loads. Plug in some space heaters and turn on lights across different circuits on the breakers that are on.

Next, measure the current on the incoming neutral vs the water pipe. If the difference is large such as more than 10% on the water bond vs the neutral something could be wrong. If more current is on the water bond then you defiantly have an open neutral.

Next, to rule out a neighbor problem trip the main breaker. With the main tripped measure the current on the neutral and water pipe. If you have more than an amp or more than a few amps something is wrong with a neighbor's neutral or a neutral out on the line.

Where do you get the notion that "some current" on a water pipe is normal?

 

[Jump-start]

Where do you get the notion that "some current" on a water pipe is normal?

Ohms law and kickoff's voltage law.

 

[brric]

Current on a water pipe is NOT normal. Why no current on the grounding electrode conductor?
Is your service stand-alone or is there a meter pack on the building?

 

[Jump-start]

Current on a water pipe is NOT normal. Why no current on the grounding electrode conductor?
Is your service stand-alone or is there a meter pack on the building?

The only time it would not be normal is if the utility transformer is not connected to earth and only feeding one home, ie the neutral comes from the utility totally ungrounded.

Current does flow on the grounding electrode conductor but often micro amps because the earth electrode is generally a high resistance. A water bond is not.

 

[brric]

The only time it would not be normal is if the utility transformer is not connected to earth and only feeding one home, ie the neutral comes from the utility totally ungrounded.

Current does flow on the grounding electrode conductor but often micro amps because the earth electrode is generally a high resistance. A water bond is not.

I respectfully disagree.

 

[Jump-start]

I respectfully disagree.

Explain your reasoning and I will explain mine.

 

[brric]

Will a 120/240 volt system operate without a grounding electrode system?

If so, where does the extra current go that you believe goes through the GES?

 

[Jump-start]

Will a 120/240 volt system operate without a grounding electrode system?

Yes, perfectly fine.

If so, where does the extra current go that you believe goes through the GES?

It goes to the neighbors (s) water bond, up through his or her neutral to the POCO pole MGN and back to the transformer. Less so, but still another path, municipal water mains are in contact with the earth for miles, the same earth that has hundreds or ground rods from the utility MGN and yards of bare neutral URD in contact with soil which again also connects to the MGN. That MGN connects to the supply transformer.


Even if the utility has no MGN (3 wire delta line) its not uncommon for a single transformer to feed several homes that share the same municipal water lines.


Current takes all paths, not the one of least resistance.

 

[terps530]

For starters, how many amps is the service? Is this over head or underground? How far away is the transformer from the house (if you know)?
Edit: You can test for an open neutral by turning off all breakers on the A or B phase but not both in addition to 240 volt loads. Plug in some space heaters and turn on lights across different circuits on the breakers that are on.

Next, measure the current on the incoming neutral vs the water pipe. If the difference is large such as more than 10% on the water bond vs the neutral something could be wrong. If more current is on the water bond then you defiantly have an open neutral.

Next, to rule out a neighbor problem trip the main breaker. With the main tripped measure the current on the neutral and water pipe. If you have more than an amp or more than a few amps something is wrong with a neighbor's neutral or a neutral out on the line.

The service is underground, and is 150A. Will check when I get home. The transformer is across the street. I would say about 75-100ft from the transformer to my service panel.
I will try these tests tomorrow during the day and report back. Thanks!

Current on a water pipe is NOT normal. Why no current on the grounding electrode conductor?
Is your service stand-alone or is there a meter pack on the building?

My service is stand-alone. It's wired/serviced just as a single-family home.

Also the units were all built 20 years ago so not relatively old.

 

[brric]

The service is underground, and is either 150A or 200A- I'm not positive. Will check when I get home. The transformer is across the street. I would say about 75-100ft from the transformer to my service panel.
I will try these tests tomorrow during the day and report back. Thanks!



My service is stand-alone. It's wired/serviced just as a single-family home.

Another possible test. Turn your main breaker off. If the issue is still present, the current is coming from the street side of your water service.

 

[terps530]

Another possible test. Turn your main breaker off. If the issue is still present, the current is coming from the street side of your water service.

I've tried this and I see no current on the pipe. It's only exists when there is a load turned on in my house. I'll double check tomorrow though.

Here's my basement water pipe IN, along with the ground wire. Tested points @ #1, #2, #3, and #4 and current shows up the same on all spots. Very little shows up on the ground wire itself. White part of pipe has no current on it.

 

[Jump-start]

I've tried this and I see no current on the pipe. It's only exists when there is a load turned on in my house. I'll double check tomorrow though.

Here's my basement water pipe IN, along with the ground wire. Tested points @ #1, #2, #3, and #4 and current shows up the same on all spots. Very little shows up on the ground wire itself. White part of pipe has no current on it.

Home fire sprinkler system? Awesome :thumbup::thumbup: (just saying its a great investment to have in any home)


If the current goes away with the main off then its caused by your neutral up to the home.

The ratio test is next (neutral vs the water bond).

 

[brric]

It's probably a crazy idea but, since concrete is conductive, you could try insulating those stand-offs from the copper pipe.

 

[ritelec]

Judging by your picture. I'm thinking a neutral somewhere is hooked to the water pipe. Especially since you say gec hardlie has anything on it.

Carefully. If you remove the gec that is attached to the water pipe and current is still there somewhere else is the connection.

At that point. Maybe the boiler I believe you said. Check circuits and those neutrals to find change.

 

[dmxtothemax]

it will take a trained electrician with a good understanding of neutral and earth systems to work out this problem.
It is not an easy DIY type fix
Please call an experienced electrician to sort it out ?
Please come back and let us know what happens ?