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Old 01-19-2009, 10:51 PM   #16
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Amp meter Results - SE Cable Bad or Power CO


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Originally Posted by InPhase277 View Post
There is something screwy with the plumbing! What other paths are there between the panel and water line within the house?
I will have to do some testing to find out where the exact contact points are but some thing I would highly suspect include; metal duct work contacting copper pipes, EMT in contact with duct work, galvanized / copper drains. Again, not sure exactly how it is all connecting, but even the galvanized DWV in the attic has almost no resistance to the ground on an extension cord.

Now before I go any further; I just got home and tried the clamp meter on my water pipe and much to my surprise, I saw similar, but not as drastic results. I have one of the same electric heaters they do, and when I ran it I was seeing about 2.5A on my water pipe by my meter. On my "sub panel" (my cuttler CH panel that everything is connected to) the ground reads less than an amp, which I suspect is in the phantom voltage range. Then on the pushmatic panel, the ground from the sub, ground rods, water meter bond, and service neutral are all connected to the neutral / ground bar.

I am even more puzzled as to how I am seeing return on my own system, since it is really a pretty clean setup with everything grounded.

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Originally Posted by InPhase277 View Post
Somewhere neutral current is finding it's way to the water line. Where is the heater you are plugging in? Is it right by the panel, or a branch circuit in the house? And have you tried on different circuits?
Back to my parrents, I am plugging it into a utility outlet I installed right next to the panel, about 2 feet of 12 gage romex. I didn't try the heater anywhere else, but did flip on a heat press in the other room (different circuit), that is connected via 12gage thhn in emt and saw similar results with the clamp meter on the water pipe.

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I know I'm asking alot of questions, but we have to get to the bottom of this. Fill in the blanks in the pics, if you don't mind.
I am going to take new readings at my parents tomorrow to make sure I am putting accurate information into the drawing for you.

I can however go take readings here and fill in the drawing with numbers from my house. I don't want to complicate the issue, but it seems I maybe having the same problem.

Now I am so confused, as to why I am seeing this happen at my house also.

Thank You

Jamie

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Old 01-19-2009, 11:06 PM   #17
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Just so we're clear, though: I'm not saying there is a problem, necessarily. But several amps seems high to me. Usually, the resistance of the service neutral is so tiny compared to the earth ground that almost all of the neutral current takes that path instead. I would not expect but a fraction of an amp to flow along the earth ground, but I suppose that if you have an exceptionally good ground, it would be possible to have a couple of amps.

I have all PVC in my house, so I can't readily take a reading. But, I will check out the service at a commercial building I'm working in tomorrow. Maybe others will chime in with their own thoughts or results.
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Old 01-19-2009, 11:17 PM   #18
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Sorry to step in this late { my time zone is diffrent than yours oh well.,, it is 6 am as I am typing }

Jamie .,,

IIRC the city water system the older main water pipes were either cast iron or steel pipe but when they do upgrading the system they gone with plastic pipe now and it pretty hard to pinpoint where is bad source is.

When you do the test and try this one { make sure you have good flashlight or portable spotlight } and turn off the main breaker first and see if the current do drop or stay the same.

If still the same then you got netural current comming in somewhere else.

I am sure Stubbie may have good drawing somewhere in his computer IIRC i think he did make one { I may be wrong on that part so I will let Stubbie answer that question }

Merci,Marc
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Old 01-19-2009, 11:31 PM   #19
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IIRC the city water system the older main water pipes were either cast iron or steel pipe but when they do upgrading the system they gone with plastic pipe now and it pretty hard to pinpoint where is bad source is.
At my parents house, It is all copper inside, but joins up to Lead pipe just as it leaves the house in the basement. In my house, it is all copper to the street.


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When you do the test and try this one { make sure you have good flashlight or portable spotlight } and turn off the main breaker first and see if the current do drop or stay the same.
If still the same then you got netural current comming in somewhere else.
I did this at my parents, and there does not appear to be any current flowing in. I'd try it here at home, but every one of my flash lights are over at my parents.

I will post the numbers in respond to Inphase in just a minute.
Thank You.
Jamie
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Old 01-19-2009, 11:49 PM   #20
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Weird. Above drawing are reading I just took at my house with a 120v electric heater running. All copper pipes in my house to the street.

I don't really understand how the water pipes are offering a path of less resistance. Even if copper is a better conductor than AL service cables, it still has to find it's way from the copper water pipe back to the transformer.

Could the power co have somehow bonded / grounded there transformer to the cities water system, making this a favorable return path?

I wonder if anyone over on Holt's site would know anything about this.

Thanks
Jamie
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Old 01-20-2009, 12:02 AM   #21
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Jamie.,

Any chance you have modern gas meter at your house ?

I did take a hard look and I am pretty sure your gas system is bonded with water pipe so grab that clamp on ampmeter and read the bonding conductor to the gas pipe and see what you come up with it.

Other wise there one way but I know it will tick off the water department with their seal on the water meter but you will have to set up a day when you are off from work and shut off the water main and literally disconnect the water pipe from the system.

WARNING Myself I could do that but My main conderastion with your situation with 3.7 amp running thru the megabuck queston is when you disconnect the water pipe it may build up voltage pretty fast how high that part I don't know it can be few volts or in 200's whatever in that range. I rather you wait until other members here suggest a safe manner to verify it.

Merci,Marc

P.S. when you did the reading was the main breaker was on or off when you got the 3.7 amp running ?

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Old 01-20-2009, 12:17 AM   #22
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Originally Posted by jamiedolan View Post
Attachment 7530


I wonder if anyone over on Holt's site would know anything about this.

Thanks
Jamie
No more than any of the pros here would, I can assure you. And the kind folks here will actually help instead of beat you about the head with falsely enlarged testes.

Jamie, this is a dilly of a pickle. What I want to know, and what we're slowly getting to the bottom of, is where the current on the water line is coming from. We know it originates from within the house, but we don't know is how it finds it's way back to the water line. So, it must go something like this: current leaves the load, goes to the neutral, then across the main bond jumper, out on a branch circuit ground wire, and across some piece of equipment in contact with or bonded to the water line.

Or, there is some neutral problem that allows current to flow through the path described above. The only way to know for sure is to un-bond the neutral and see what happens to the readings then. If you remove the bond jumper (screw, strap, etc), and the current persists, then there is a branch neutral leaking somewhere. If you remove the bond and everything goes wacky and unbalanced, then the service neutral is bad. If you remove the bond and nothing happens and the readings go to zero, then we are looking at a natural occurance.
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Old 01-20-2009, 01:57 AM   #23
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No more than any of the pros here would, I can assure you. And the kind folks here will actually help instead of beat you about the head with falsely enlarged testes.
No offense intended to you at all. My comment might have come off wrong. I had heard of Holt as having written "the book" on grounding and bonding. Thats the only reason I even thought of it.

Quote:
Originally Posted by InPhase277 View Post
Jamie, this is a dilly of a pickle. What I want to know, and what we're slowly getting to the bottom of, is where the current on the water line is coming from. We know it originates from within the house, but we don't know is how it finds it's way back to the water line. So, it must go something like this: current leaves the load, goes to the neutral, then across the main bond jumper, out on a branch circuit ground wire, and across some piece of equipment in contact with or bonded to the water line.
I should perhaps do these things when I am more awake. I spent some time looking for where my water pipe contacts other metal and putting cardboard between it and the ducts, emt, and other pipes. Only to realize, that the copper pipe is connected to the water heater that is connected to the gas pipe that is connected to the furnace that is connected to emt.... So short if removing gas pipes or emt that are installed, I am not going to be able to isolate the water pipe atleast not in my house.

Quote:
Originally Posted by InPhase277 View Post
Or, there is some neutral problem that allows current to flow through the path described above. The only way to know for sure is to un-bond the neutral and see what happens to the readings then. If you remove the bond jumper (screw, strap, etc), and the current persists, then there is a branch neutral leaking somewhere. If you remove the bond and everything goes wacky and unbalanced, then the service neutral is bad. If you remove the bond and nothing happens and the readings go to zero, then we are looking at a natural occurance.
At my house, I could remove the ground connection from the sub panel. I could also disconnect the bond to the water meter in the main SE panel (the pushmatic). But no matter what I do electrically, that furnace and water heater are still going to be connected to the gas pipe and the water pipes.


So it become not as much of a question of how it gets to the water pipes, but why go there at all when it would appear a path of less resistance is available. Also my ground rods that I know are in well, don't seem to want to carry out any of the amp. So the only thing that comes to mind for me at all is if the powe co bonds to the water pipes thus causing them to be a favoriable return path.

Does electricity need to return to the same transformer that it came from or could it return to a different transformer if there was less resistance to another one?

Jamie
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Old 01-20-2009, 02:07 AM   #24
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Quote:
Originally Posted by frenchelectrican View Post
Jamie.,

Any chance you have modern gas meter at your house ?

I did take a hard look and I am pretty sure your gas system is bonded with water pipe so grab that clamp on ampmeter and read the bonding conductor to the gas pipe and see what you come up with it.
Yes, at both my house and my parents there is gas service. However, I am almost positive that both are fed from the street with Pex. My system was never bonded to the gas pipes directly nor was my parents. I know I need to add a bond to my gas pipes, one more upgrade I have been meaning to do. I figured that it was fairly well bonded since there is EMT to the furnace than the furnace has gas on it.

Quote:
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Other wise there one way but I know it will tick off the water department with their seal on the water meter but you will have to set up a day when you are off from work and shut off the water main and literally disconnect the water pipe from the system.

WARNING Myself I could do that but My main conderastion with your situation with 3.7 amp running thru the megabuck queston is when you disconnect the water pipe it may build up voltage pretty fast how high that part I don't know it can be few volts or in 200's whatever in that range. I rather you wait until other members here suggest a safe manner to verify it.

Merci,Marc

P.S. when you did the reading was the main breaker was on or off when you got the 3.7 amp running ?
I can turn off the water and pull the meter at any time. I have grounding rods in place, so wouldn't it be likely that the return would flow out via the grounding rods or the service neutral before anything harmful happened? If I try that at my parents tomorrow, I'll treat it as live until proven otherwise.

When I read the 3.7 here that was with the power on and my little 120v heater running. I found a flashlight here and turned off the power. I get almost nothing when the power is off, maybe .15 to .20 A, phantom readings I would kind of guess.

I really doubt there is a problem with the setup at my house since I have re-wired much of it and there are no signs of a loose neutral. It just puzzles me as to why it chooses the water pipe for a return.

I am more concerned about my parents setup after the short last week and the disco and reconnect. I am thinking it is more likely that they could have a bad / loose connection somewhere.

Thanks
Jamie
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Old 01-20-2009, 08:35 AM   #25
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No offense intended to you at all. My comment might have come off wrong. I had heard of Holt as having written "the book" on grounding and bonding. Thats the only reason I even thought of it.
I wasn't taking wrong, I knew what you meant. Sure if you talk to Mike himself you may get some help. But the rest there seem to sidetrack on the smallest quibbles and run a thread to 25 pages arguing the difference between potato and potatoe. It's quite ridiculous.



Quote:
I am not going to be able to isolate the water pipe atleast not in my house.
Right, not from the ground bus anyway. What I was saying is to completely isolate the ground from the neutral. The neutral and ground are bonded together. If we can separate this bond, then we can tell what the current path is. In other words, we need to unground the neutral completely so that there is no intentional electrical connection to the ground wires of the branch circuits.

If most of your branch circuits now originate from your new CH panel, and not the pushmatic, it would be as simple as disconnecting the ground feeding your CH panel.



Quote:
Does electricity need to return to the same transformer that it came from or could it return to a different transformer if there was less resistance to another one?

Jamie
Unless two transformers share a secondary neutral connection somehow, then current can only return to its transformer.
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Old 01-20-2009, 12:10 PM   #26
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The problem with measuring currents in very low impedance circuits is
V/R = I.
If I is 1A then V could be 120v (and R = 120 ohms) or
V could be 1V (and R=1 ohm) or
V could be 100 mV (and R=100 milliohms).

And which way is the power flowing?

If V on one side of an opened circuit is 1V higher than the V on the other side, with 0.1 ohm the current can be 10A (but the power is always flowing in the direction from high potential to lower potential.

To figure pass/fail specs you need a diagram: of every bolt, length of wire, length of copper pipe (what wall thickness?), corroded connection, etc.

Without special test equipment you will need to calculate, infer and assume. You may not have a problem at all, or these currents may vary due to factors outside your house.

If, when we're done it still doesn't make sense, then you need to haul out an O'scope.

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Old 01-20-2009, 12:25 PM   #27
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Lets start with the diagram below




I didn't read all this but I am assuming we determined that all the current is leaving the house over the water pipe main line?

As you can see there can be a somewhat low impedance path to the transformer via the water pipe to your neighbors plumbing then to the service neutral at his house via the water pipe bond at his home.

The set of readings you took on your house would be correct assuming zero amps on the water service prior to turning on the 12.5 amp heater. It simply means that 1.2 amps of the heater is returning on the water bond and 2.6 amps is returning on the cold water pipe culminating with approx. 3.6 amps on the main after the water bond clamp. so it is safe to say that the currents on the water pipe bond and cold water pipe are adding and in the same direction otherwise the main line before the clamp (water service side) would be less than the total amps flowing as shown in your diagram. So basically I'm saying that it certainly appears that the amperage is on the same leg and directly related to the heater. You could do the same by operating your toaster.

The question now is why is the current on the water pipe before the clamp (house side) for the water pipe bond greater than the water bond conductor #4 itself?

I would expect it to be the opposite. And because of that I would say this is not a common expectation, other wise I would just tell you to move on that all is normal.



Can you get a amp reading at the cold water line at the hot water tank?

Can you get a reading at the hot water pipe at the tank?

In some homes the cold and hot are bonded by a jumper at the hot water tank just a heads up.

BTW...you flirted with death by removing the water pipe bond. By this I mean had you touched the water pipe bond with one hand after you disconnected it and the main water pipe with the other hand you put yourself in series with the low impedance and that current will flow thru you to the water pipe. Always connect a jumper between the the two before you disconnect them. Many plumbers have discovered this the hard way.
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Old 01-20-2009, 03:01 PM   #28
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It simply means that 1.2 amps of the heater is returning on the water bond and 2.6 amps is returning on the cold water pipe culminating with approx. 3.6 amps on the main after the water bond clamp. so it is safe to say that the currents on the water pipe bond and cold water pipe are adding and in the same direction otherwise the main line before the clamp (water service side) would be less than the total amps flowing as shown in your diagram. So basically I'm saying that it certainly appears that the amperage is on the same leg and directly related to the heater. You could do the same by operating your toaster.

Hello;

Thank you for responding, I will answer you in more detail and provide the tests results later on this evening, I just have a moment now.

After much more testing at my parents house this am. I have come to find the following:
With service off: no amps on water pipe
With service on only to one 12 A heater and nothing else (metered the BC and have 12A going out and 12A coming back on the neutral); I'll see a return on the service neutral of about 9 amps and on the water pipe I see about 4.5A.

Some how I have an extra 1-2A of return, where could this possibly be coming from?

After extensive invlovement from the power co and engineering, we do not have any answers. The Service drop cable tested good, I removed the SE cables and inspected and put nolox on them and reinstalled them.

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Originally Posted by Stubbie View Post
BTW...you flirted with death by removing the water pipe bond. By this I mean had you touched the water pipe bond with one hand after you disconnected it and the main water pipe with the other hand you put yourself in series with the low impedance and that current will flow thru you to the water pipe. Always connect a jumper between the the two before you disconnect them. Many plumbers have discovered this the hard way.
Klien makes great insulated tools. I treated it as live until my meter proved it to be dead.

Thank you again, I will get the other meter readings this afternoon and post a more complete update then.

Thank You

Jamie
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Old 01-20-2009, 04:45 PM   #29
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Quote:
Klien makes great insulated tools. I treated it as live until my meter proved it to be dead.
When you disconnected it your meter should go to 0 amps. So a zero reading only means you opened the connection. The minute you touch both the conductor and the water pipe you close the connection and the current flows again.

If your speaking about voltage then that can be true but remember you would not get appreciable voltage readings from neutral current.
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Old 01-20-2009, 06:13 PM   #30
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I'll see a return on the service neutral of about 9 amps and on the water pipe I see about 4.5A.
So the pipe has a higher resistance than the neutral, assuming they are paralleled?

Some how I have an extra 1-2A of return, where could this possibly be coming from?
Check the accuracy specs on your ammeter; usually it's a percent of full scale [+/- a few digits for a digital readout]. These specs are sometimes hard to figure out but this may be measurement error. You have a link to your meter's specs?

If I haven't made an arith. error, 3/4" pipe with 1/16" wall thickness and 7/8" O.D. has a cross-section equal to a round wire 450 mils in dia.

Calculating the AC resistance due to skin effect of a tubular conductor like this is beyond me but there is at least one company who makes tubular conductors and from their data I think the AC resistance of this pipe is 14% higher than what you'd expect from a solid conductor 0.45" in diameter.


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