My Water Main is Hot

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Joethemechanic

Senior Member
Location
Hazleton Pa
Occupation
Electro-Mechanical Technician. Industrial machinery
I've been playing around with grounding and gradients in the back yard. Well I've got a good (below 4 ohm) ground rod driven in the middle of my back yard. So when this known good ground rod is connected to my water service I have 0.2 (+-) amps flowing. I thought I must have something coming from my house or the utility to make it hot, but I disconnected the bond and the current is still there. Even opening up my main breaker has no effect.


If I ground the electric service using only driven ground rods (and I got a bunch of them) I get zero current.


I've really never tested a water pipe ground before to see exactly what potential it is at before, but 2/10 of an amp flow to driven ground rods seems kinda high

All I can think is someone in this devolopment (built 1953 all copper water mains) must have some kind of serious ground fault issue.


Anybody else have any ideas?
 

iwire

Moderator
Staff member
Location
Massachusetts
All I can think is someone in this devolopment (built 1953 all copper water mains) must have some kind of serious ground fault issue.


Anybody else have any ideas?

Yeah, with all metal water lines the water line becomes a parallel neutral and will carry current.

Sometimes the current is because a neighbors neutral is open but even with everything perfect you can expect some current flow.
 

kwired

Electron manager
Location
NE Nebraska
It is bonded to service neutral as well as POCO primary neutral, making it an extension of both of these conductors. What you are measuring could (probably is) simply be voltage drop on the primary neutral.
 

iwire

Moderator
Staff member
Location
Massachusetts
What you are measuring could (probably is) simply be voltage drop on the primary neutral.

If I run a parallel set of service conductors would you call the current measured on one phase A conductor the result of VD on the other phase A conductor?
 

Joethemechanic

Senior Member
Location
Hazleton Pa
Occupation
Electro-Mechanical Technician. Industrial machinery
Well with nothing electrical at all connected to the water service in my house, and just a piece of 14 gauge wire coming from my ground rod array in the back yard (about 100' away). I have 2/10 of an amp flow give or take. Is that high, or normal? I understand the parellel neutral thing. It just seems higher than I thought.


This is the extent of the circuit. I have eliminated everything else.
 

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Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Joe-- I am curious what the voltage is from Hot to the rod at 100 feet away. I had one guy tell me he could run his drill that way but he was connected near the service.
 

PetrosA

Senior Member
It sounds pretty normal to me. Maybe an easier way to imagine what's happening is to visualize a two meter system (since you're in PECO territory, you're probably familiar with the off-peak meters). If you have the GECs going from both the main panel and the off peak panel to the ground rod, you will be able to measure current on them because you've created a parallel path for the neutral in the main panel to the neutral in the off peak panel and back to the transformer through your GECs. If you just had one conductor out to the rod and the off peak bugged to it, there would be current on the section between the main panel and the bug, but probably very little on the section going out to the ground rod.

Considering that PECO runs a ground rod down from the primary neutral every so many poles and at each transformer, the soil also becomes a parallel path for neutral current. Metal water mains also become a parallel path. Measuring between any two points in the soil or between soil and a neutral point will show some voltage and current.

If you measure voltage in your setup, you probably won't get more than 3-4 volts unless there is a damaged neutral someplace. 200 mA sounds like a lot, but as long as the voltage is very low, you probably wouldn't even feel a tingle if you completed the circuit yourself. Where it gets dangerous is when a neutral is lost or seriously damaged (high resistance) and the MAIN or ONLY return path is through a metal water pipe or earth ground.
 

Joethemechanic

Senior Member
Location
Hazleton Pa
Occupation
Electro-Mechanical Technician. Industrial machinery
An Ideal amp clamp.

I just checked it for the first time today, and it's down to 7/100 of an amp.

It was steady around that 2/10 of an amp reading for about 3 days since I first noticed it.


Although there are 2 major differences here now, It is about 30 degrees warmer out, the snow melted, and the ground is really wet now.

Not sure to attribute the lower reading to wet ground, or if there is a reduced load on the utility due to the warmer weather.


BTW, I got my driven ground rod array down to that low resistance by pushing pieces of copper tubing in the ground that had holes drilled in the sides, and pouring salt water in them.
 

Joethemechanic

Senior Member
Location
Hazleton Pa
Occupation
Electro-Mechanical Technician. Industrial machinery
Joe-- I am curious what the voltage is from Hot to the rod at 100 feet away. I had one guy tell me he could run his drill that way but he was connected near the service.


I was going to try to measure it, but I need new batteries for the meter. I got that last reading from heating up the old batteries in a cup of hot water and then putting them back in the meter. lol


I kinda think I should shunt the volt meter with something so I'm not just picking up some darn false reading
 

Joethemechanic

Senior Member
Location
Hazleton Pa
Occupation
Electro-Mechanical Technician. Industrial machinery
Dennis,

Yes, one hot wire (120V) and a driven ground rod approximately 100' away from any ground rods or underground water pipes will run my Milwaukee 3/8" drill. Not sure how much power, but I couldn't hold the chuck still with my hand.


My own little SWER lol
 

Joethemechanic

Senior Member
Location
Hazleton Pa
Occupation
Electro-Mechanical Technician. Industrial machinery
Must be a great clamp, I often read a few amps clamped on nothing.

I just don't have much faith in clamps at those low currents.

Well after my radio shack trip tomorrow, I'll hook up something hard wired inline and see what kind of readings I get
 

hurk27

Senior Member
Well after my radio shack trip tomorrow, I'll hook up something hard wired inline and see what kind of readings I get

Joe, way back in the late "70's" when I was doing some lightning/grounding studies at the University of Florida, Gainsville, I did many experiments like this and quit a few others. A member who was on the forum allot did some of these same experiments and found many of the same results I have found, although he has not been on here in a while, he did leave a vary good thread along the same lines as what you are doing which might be a good read, also look at the link in the first post to the thread that started his wish to do these experiments:

http://forums.mikeholt.com/showthread.php?t=116358
 

SG-1

Senior Member
Check for DC too

Check for DC too

Joe, while you are measuring voltage be sure to check for DC also. I was checking the farm for stray voltage a while back & found some low level DC between the service & remote earth.
 

the blur

Senior Member
Location
cyberspace
My house is similar, but it's about 3 amps ground current. I was playing with it a few years ago. I turned off the main, and I still had ground current. The reason is someone in my neighborhood has a bad neutral. and the pot serves 5 houses. also it was determined I have the best service entrance in the neighborhood, a 2o copper service, so I am the path of least resistance. The problem was never solved, and no one really cares.

I never thought about harvesting the power. 3 amps is alot, and I'm sure it could power my fish tanks.

I also tried this experiment at the shop with a 208Y, and the ground current is 0. We have our own pad mount. :cool:
 

kwired

Electron manager
Location
NE Nebraska
If I run a parallel set of service conductors would you call the current measured on one phase A conductor the result of VD on the other phase A conductor?

Yes. If voltage drops the same on both conductors of the set then the current will be equal on each, if one has a higher resistance (even a little bit) the other one is going to carry more current. Isn't that why they are supposed to be same physical properties when paralleled?

In OP situation each parallel element is not same resistance therefore different voltage drop across each path and different current level in each path.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
110126-1946 EST

Some general comments:

The meters I usually use are a Fluke 27, 87, and a Beckman 4410. In some ways the Fluke 27 is a better meter because on AC it has a lower internal noise level. Reads 0 with the terminals shorted. The 27 is average reading, the other two are also averaging meters but the averaging is done in the RMS measurement.

Voltage measurements between two points in the ground with high input impedance meters are not erroneous measurements, but rather an indicator of ground current. I typically space two screw drivers 12 ft apart for this voltage measurement to sense ground current.

To prove that you are not measuring a magnetically induced voltage connect another insulated wire between the two probe leads at the 12 ft distance, but not connected between the screwdrivers so as to simulate the one turn loop created by the test leads and the earth. I have always read zero. In other words no induced voltage of importance.

Across the probes in my backyard I get readings of maybe 10 millivolts to several hundred millivolts. The readings are direction, position in the yard, and time sensitive. I have not done the experiments with any tuned filters.

I would like to create a setup with 8 probes. Two for NS, two for EW, two for SW-NE, and two for SE-NW. Then make simultaneous average readings with filtering at 60 Hz, and separately at 50 Hz, if 25 Hz still exists, then at that frequency as well. Also do similar instantaneous measurements without filtering.

One day I took a ride in the country to an isolated area somewhere near the Waterloo Recreation Area, and found a place where the 345 kV lines crossed the road and there was some parking space. In fact this was probably at the interconnect point between DTE and Consumers Power. I was looking to see if there was a current component that looked like it was associated with the transmission lines. What I found was the maximum current direction was somewhat perpendicular to the power lines. I did not pursue the experiment further.

In my front yard at home I have a 100 ft or so of copper water supply line from the city water line to my basement. I believe the city pipe is cast iron. About 20 ft from the street the direction of current flow in the earth is perpendicular to my copper pipe. This is to be expected. It should be noted that I am supplied by an ungrounded delta primary. It is probably a Y at the substation and grounded there about 3/4 to 1 mile away. Only two houses, and two street lights are on my transformer. My neighbor and my house are at the end of a block. His house faces a street that runs perpendicular into my street. His house faces the long part of the block, mine the end of the block. My water does not come from the front of the house, but from the south end. I don't believe there is a city water connection at my end of the block, or my water would have come from the front, not the end. Thus, connection via city water line between our houses is probably over 3000 to 4000 ft. But we are obviously connected by the same power company neutral. I do read current to the water pipe.

Presently I see no value in putting a low impedance shunt between two probes in the ground and measuring the current. I do not know that this value would be of any importance. Does anyone have reason that this should be important? But current measurements to ground rods and water pipes that connect to a service are important.

I should point out that by using a high impedance meter to the probes basically eliminates the effect of probe to ground resistance on the measurement. A few hundred ohms compared to 10 megohms is of no great importance.

.
 

hurk27

Senior Member
You know Gar, it is getting harder and harder to find any location that doesn't have any electrical installation that is more then a few miles away without going out west or maybe down in the middle of the Everglades about anywhere I go around here you always seem to be able to spot a power pole some where on the horizon, I wish I had the resources to get another low frequency spectrum analyzer and the time to just see what is being pumped through the earth, I can remember years ago using a spectrum analyzer just by connecting it to a couple driven pipes you would see peeks at 60hz, and 50hz and a few others that was explained to me of the submarine communication carrier frequency's, but it did show that the 50hz came from the power grids of Europe, this was done outside of Gainesville, Florida in a remote area north east a few miles out off state road 24.

Also the voltage you are reading is just like measuring current and the earth is the shunt, the problem is that you are not just measuring one current but many, some in phase some out, some that cancels each other, the other thing is that the earth is not just one path between two points, but many paths in all directions, you are connecting your two probes to just the outside of a very large 3D conductor something like a very large conductive solid ball with current flowing through it and you touch your probes at two points on this ball to read the current flowing between the two points, a good experiment would be to inject a current at a dead band frequency (one that is not used by another source) then design a voltage probe that is notched to only this frequency, and then test to see the current flow pattern 360? around the injection point, this would isolate that you would only be receiving and measuring this one current that you injected?
 
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Joethemechanic

Senior Member
Location
Hazleton Pa
Occupation
Electro-Mechanical Technician. Industrial machinery
Ok, for right now I'm stalled, Reason #1 it's raining

Other reasons are, I got to get some more scrap copper tubing for ground electrodes, The tubing works the best because I drill a few pin holes in the sides and fill them with salt water. Salt water makes a huge difference.

I got to get some cheap, or maybe scrap wire. I am not using up any more of the MTW from my truck. I'll end up on a midnight emergency and be 2 feet short of what I need the way my luck goes.

I want to take a trip to my buddy's scrap yard. I want to find some transformers for boost buck, and Isolation. I also want to find some small 3 phase motors, capacitors, and whatever else looks interesting.

BTW, Dennis

With a 4 foot length of 3/4" copper tubing sunk to a depth of about 3 1/2 feet, filled with a strong salt water solution, and one 120V hot wire,,,,

AND hooked to a boost-buck hooked to boost @ 32V. My 3/8" Millwalkie drill runs as close to full power as I can tell. That is when the rain started and I gave up
 
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