Trouble shooting customer getting shocked at hose bib

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Scenario description:
The customer stated that when she touches the hose bib in bare feet she gets shocked.
There are 3 buildings on this property with all meters for the three buildings being at the side wall of the main house
Building 1
Building 2
Building 3

There is a pad mounted transformer installed 50? to the left of the main house. Service to the main house is 400 AMP service. Connected to the main house meter is a 200 AMP meter with service delivering power to the garage apartment. Service to the pool house is a 200 AMP service from pad mounted transformer.

NOW TESTING
1. With power on the results were as follows:
? GARAGE APARTMENT
o Hose bib to dry asphalt 0 volts
o Hose bib to wet asphalt 32 volts
? MAIN HOUSE
o Hose bib in area of meter 0 volts
o Hose bib to earth 32 volts
o hose bib to ground rod 0 volts
o hose bib to metal meter box 0 volts
o Hose bib to neutral connection in
electric meter 0 volts

2. Turn off all power by pulling the meters out of the pool house, garage apartment and main house. I turned off main breakers in the main house.
? GARAGE APARTMENT
o Hose bib to dry asphalt 0 volts
o Hose bib to wet asphalt 0 volts
? MAIN HOUSE
o Hose bib in area of meter 0 volts
o Hose bib to earth 0 volts
o hose bib to ground rod 0 volts
o hose bib to metal meter box 0 volts
o Hose bib to neutral connection in
electric meter 0 volts

3. Reinstalling the meters in the following order I received the following results:
? Meter for the Garage Apartment was reinstalled and a reading of 0 volts from hose bib to earth at the main house.
? Meter for the Pool house read 8.5 Volts from hose bib at house to earth.
? Main house circuit breakers were closed. The reading at the Hose bib at house climbs to 32 volts.
? After reinstallation of all meters were completed, the Fluke meter leads were pushed into the ground about 6? apart and voltage read was 29. This was done in the electric meter location.

Of Note: During the testing phase, a contractor repairing the on-site sanitary system damaged the direct burial cable that ran from the meter location to the garage apartment. With the meter pulled, I repaired the damaged cable and during that repair the following was occurring:
To repair the cable, I spliced the cable and installed two underground connectors and a small jumper. I was getting shocked from both the meter and garage sides of the neutral conductor, prior to power being restored.

Any ideas? Am I overlooking anything?
 

Smart $

Esteemed Member
Location
Ohio
Was the testing done after fixing the DB feed to garage?

This is a process of elimination. You have covered some, but incomplete.

You read voltage with meter for garage and pool in, with none when only garage was in. You need to confirm the problem for this voltage is not occuring between garage and pool, so pull meter for garage while leaving pool in and check for change, and track down any voltage.

The method should be one in at a time, take readings, fix any aberrations, then two in at a time, and you should have located the problem before getting to putting all three in.

Of course as you narrow it down, all non problem feeders and circuits will be deenergized leaving only the ones supplying the voltage energized... and please be very careful... it appears the earth is the energized source where you are measuring. At the very least, wear EH-rated boots and avoid touching [direct skin contact] any conductive parts such as the hose bib, meter enclosure, etc.
 

hurk27

Senior Member
Go to the transformer and with all loads on, see what you have between the transformer case and Earth, use a rod of 2' to at least get down into the moisture part of the soil, if you have voltage here then you have lost the concentric neutral to the transformer this is common failure in older installations where the concentric is exposed, newer ones have a jacket around the concentric, if this proves true then also have the POCO check this neutral connection at the point of connection to the MGN back at the main pole, as this will cause the same problem. had the same problem several years ago and as time went on the water main went bad so they use a plastic pipe to replace the copper, this elevated the voltage to about 56 volts, loosing any more local Earth grounds will cause the voltage to go even higher as high as the primary, so do not remove any grounding if you have voltage to earth from the transformer case, if you don't have the voltage there then you likely have a bad secondary neutral problem and are pulling a return path through your grounding, this can be tested by placing an amp probe on each system grounding conductors.
 

hurk27

Senior Member
to explain your readings, is the reason the pool is giving you a lower reading then the main house is because the grounding at the pool probably is greater then the electrodes at the house or garage, if this pool has a equal potential grid, this would explain this, since you have two or more points of voltage with only the transformer as a common point then you need the POCO out there right away, because if you have a lost concentric neutral to that transformer, you have a dangerous situation.

DO NOT REMOVE ANY GROUNDING ELECTRODE CONNECTIONS OR SERVICE NEUTRALS, IF YOU HAVE VOLTAGE TO EARTH ON THE TRANSFORMER!!!!!
 
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Smart $

Esteemed Member
Location
Ohio
...
This is a process of elimination. You have covered some, but incomplete.
...

...

Any ideas? Am I overlooking anything?
Additionally...;)

...wherever you read voltage from grounded part to earth, also check voltage line-to-neutral and line-to-earth. Deviation from nominal will show which probe location is the source of energy. And as Wayne mentioned, it will help confirm whether this is a result of a faulty neutral.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
100704-1411 EST

ctselectric:

You appear to have substantial current flow in the earth. I use screwdrivers for probes into the earth and alligator clips from the meter leads to the screwdrivers. I like the Fluke clips. I also use about 6 foot leads, meaning 12 feet between the test points. You can determine the direction of the current flow by changing the relative orientation of the probes. Minimum voltage occurs when the line between the probes is perpendicular to the direction of current flow. Maximum when parallel.

3. Reinstalling the meters in the following order I received the following results:
? Meter for the Garage Apartment was reinstalled and a reading of 0 volts from hose bib to earth at the main house.
? Meter for the Pool house read 8.5 Volts from hose bib at house to earth.
? Main house circuit breakers were closed. The reading at the Hose bib at house climbs to 32 volts.
? After reinstallation of all meters were completed, the Fluke meter leads were pushed into the ground about 6? apart and voltage read was 29. This was done in the electric meter location.
Where is the earth probe point relative to the house hose bib

Meter to Pool House was reinstalled and 8.5 V was read. Did the meter probe in the earth change position?

Scenario description:
The customer stated that when she touches the hose bib in bare feet she gets shocked.
There are 3 buildings on this property with all meters for the three buildings being at the side wall of the main house
Building 1
Building 2
Building 3
Are there three meters or two meters?


There is a pad mounted transformer installed 50? to the left of the main house. Service to the main house is 400 AMP service. Connected to the main house meter is a 200 AMP meter with service delivering power to the garage apartment. Service to the pool house is a 200 AMP service from pad mounted transformer.
What is the arrangement here? Is there a main house meter that only has load in the main house? Is the garage apartment meter fed from the main house meter? I doubt it.

I suspect what your a saying is that from the pad mounted transformer there are one or more drops from the transformer to three meters on the side of the main house. And no meter feeds a second meter. Logically I would assume these three meters are adjacent to one another.

One meter supplies power to the main house. One meter supplies the garage apartment. And one to the pool house.

If there is only one service drop to the meters, then there should be near 0 volts between the three neutral output lugs from the meters. Near 0 probably means less than 0.5 V with or without load and the same to the grounding electrode. If there are different service drops, then the voltage might be somewhat higher with load, but maybe less than 2 V.

When I know how these meters are wired and where they go, then I have more questions.

.
 

hurk27

Senior Member
I try to flag these post when I see voltage to Earth between two separate points and Earth with only the transformer as the common point between them I had this problem on an apartment building and after reaching the conclusion that it was in fact the primary concentric neutral, the line man tried to say it was the secondary neutral and thus removed under load this secondary neutral and quite an arc between this secondary neutral and the terminal and conductor he hooked it back right away realizing what I was saying was true, luckily he had his insulating gloves on, he just sat there and said wow, then said if we would have removed the main service neutral or grounding electrode bonding for the building the same thing would have happened at that end, and most likely the building would have been gone.

If you even have voltage between a pad mounted transformer and Earth immediately suspect the primary neutral, and get a hold of the POCO ASAP.
 

dbuckley

Senior Member
The first thing to note is that the 32V dissapeard when the meters were pulled, so this is something to do with this installation specifically (including the PoCO's transformer and wiring), not something attributable to external problems, such as a busted PoCo MGN. The stray current must ultimately be coming from one of the hots, so its either a high resistance leak from a hot, or a leak from voltage drop across a neutral.

Do I understand correctly that there are two services from the transformer to the main house wall; one that supplies just the garage through one meter, and the other supplies the house and the pool house through two meters. The N/G bonds are in the panels at each location, and each panel has a ground rod or two.

On to troubleshooting: Lets assume a leaky circuit.

On the main house panel, does switching on any breaker with a load on it cause the voltage to rise to 32V, or just some (or one) breaker(s)?

Identify a single breaker at the main house that when turned on causes the voltage to rise to 32V. Switch everything off, and identify that circuit's neutral. Depending on how tidy the panel is, that might be fun... Measure resistance (megger is best) from each of the hot and neutral conductors to the ground bar. In both cases you should read an open circuit. If its not then that circuit is leaking to ground, and that problem needs to be identified and fixed.

From thousands of miles away on the net, this smells like there might be multiple problems, so this could take a while.
 

hurk27

Senior Member
The first thing to note is that the 32V dissapeard when the meters were pulled, so this is something to do with this installation specifically (including the PoCO's transformer and wiring), not something attributable to external problems, such as a busted PoCo MGN. The stray current must ultimately be coming from one of the hots, so its either a high resistance leak from a hot, or a leak from voltage drop across a neutral.

I don't understand the reversal ot the two statements (above in red)

One say it can be the wiring of the transformer, which would include the transformer connection to the MGN.

And the other States it can't be?:confused:

And with a pad mounted transformer, it sure can be, because anytime you loose the concentric neutral connection between the transformer and the MGN everything bonded to this neutral which includes the secondary neutral and all the grounding done at the house, pool, garage, will become a return path for the primary current of the transformer, this will elevate the voltage on this grounding proportionally to the resistance of the pathway and the current being drawn on this pathway.

The higher this resistance gets, the higher the voltage can get, all the way to the full voltage of the primary, which here would be 7200 volts.
 
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Shocking hose bib

Shocking hose bib

Thank you all for your advice and suggestions. I am happy to report that after a long consult with the POCO (PECO Energy Company) last night we discovered it was the concentric neutral from the pad mounted transformer to the pole. It has been temporarily resolved and your advice was very helpful.

Thank you again!
 
trouble shooting customer being shocked by hose bib

trouble shooting customer being shocked by hose bib

Thank you all for your advice and suggestions. I am happy to report that after a long consult with the POCO (PECO Energy Company) last night we discovered it was the concentric neutral from the pad mounted transformer to the pole. It has been temporarily resolved and your advice was very helpful.

Thank you again!
 

hurk27

Senior Member
Thank you all for your advice and suggestions. I am happy to report that after a long consult with the POCO (PECO Energy Company) last night we discovered it was the concentric neutral from the pad mounted transformer to the pole. It has been temporarily resolved and your advice was very helpful.

Thank you again!

Glad you got to the bottom of this and got it taken care of, as I said, this condition could be very dangerous, and a un-knowing electrician could have come along and un-knowingly disconnected the electrode connections or service neutral in the testing process and would have had the primary voltage sitting in his hands.

Anytime you see voltages over 10 volts to Earth from the grounding system, suspect a lost transformer neutral to MGN connection, very rare on a pole mounted transformer but it does happen, more common on a pad mounted transformer.
 

dbuckley

Senior Member
I don't understand the reversal ot the two statements (above in red) One say it can be the wiring of the transformer, which would include the transformer connection to the MGN. And the other States it can't be?:confused:

Ok, let me try and explain where I'm coming from....

In a typical installation there are two possible sources of stray current.

One is attributable to leakage from "stuff" relating to that installation itself, and for this type of problem the stray current goes away when you open breakers and remove meters. This type of stray is usually attributable to a genuine fault (ie something has gone wrong and it can be fixed to make the problem go away), or by less than good design, but a design still in full compliance of the NEC.

The other is type unaffected by breakers and meters, and is still present when the meter is missing, the disco off and all the breakers open, and you've ripped the hots off the weatherhead. I call this type "ground versus ground" leakage. For this category, the currents are sourced from outside of the immediate installation, often attributable to voltage drop along an MGN between poles and transformers. There is no fault to be fixed for this type of problem, it is a feature rather than a fault. You have to "work around" the problem.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
100708-0804 EST

Consider the following experiment:

An insulated box 1 mile long, 100 ft wide, 10 ft deep. At each end of the 1 mile length put a 10 ft x 100 ft conductive plate. Fill this box with a uniform earth material. Apply 1000 V 60 Hz between the two end plates.

There will be an interface impedance between the end plates and the earth material, but assume this voltage drop is nil.

Because of the uniformity of the structure and the contained material there is uniform current density throughout the earth material. The voltage drop over a 10 ft distance in the long direction is 1000*10/5280 or 1.89 V, and over 3 ft (1 step) it is 0.57 V.

Next bring an insulated conductive wire from one end plate to the 1/2 mile point. What is the voltage between the wire and the earth?

Then drive two rods in the soil spaced 50 ft apart and lined up in the long direction of the experiment. What is the voltage difference between the two rods?

Shift the orientation of the 50 ft spaced rods so the orientation is perpendicular to the long direction of the experiment. What is the voltage between the rods?

.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Was this supposed to be tough?

Next bring an insulated conductive wire from one end plate to the 1/2 mile point. What is the voltage between the wire and the earth?
500v

Then drive two rods in the soil spaced 50 ft apart and lined up in the long direction of the experiment. What is the voltage difference between the two rods?
9.45v

Shift the orientation of the 50 ft spaced rods so the orientation is perpendicular to the long direction of the experiment. What is the voltage between the rods?
0.0v
 

hurk27

Senior Member
While I under stand the physics of this Gar, I just don't understand where this come into play in the real world?

current takes all paths, not just the path between two points, the Earth is a 3-dimensional globe, and current will take all paths in this globe to reach the other point, and this includes down into the Earth, if we remember the experiments Gary carried out, it clearly shows that when he placed the rods at two different directions to the injected site, the voltage drop off was in for most account equal in both directions once you leave the relative high resistant area of Earth next to the injection point, placing the rods in equal points 360?s around the rod will still result in the same answer, the current flows equally in all directions from the injection point, this has been proved by experiment using an isolated current source, and a return path rod placed out of the Sphere of influence, (about 26' away) voltage drop off was equal in all directions from the rod at more then 4' distance, at 3 feet 75% of the voltage will be reduced, at 26' 99.9% of the injected voltage will be gone.

This why I say stray voltage almost always comes from a source very close to the affected area, in this case, the grounding because of the lost concentric neutral on the primary side had 32 volts above Earth, the voltage was not because Earth was at 32 volts, but because the grounding was at 32 volts above Earth.

Do we call this "stray voltage" ? well we could, but in the sense of traveling through earth no, no more then we could call the 120 volts we could measure between a hot and Earth "stray voltage" to me when we speak of stray voltage we are speaking of a voltage that is coming in from a source through the earth, but every time I stick my probes into the ground I find its DC, or a different frequency then the 60hz we are trying to say it is coming from?

If injecting a 120 volt current into a rod in Earth will drop almost all its voltage at no more then 26' away from the injection point, how can a grid system that all power systems in the US use that is referenced to Earth at every ? mile cause a voltage to be detectable at a great distance from the problem area point? I've seen the test and done test in this area, and even helped direct Gary in doing one right here on this site, I just don't believe all that is being said by just a few people.
 

hurk27

Senior Member
Ok, let me try and explain where I'm coming from....

In a typical installation there are two possible sources of stray current.

One is attributable to leakage from "stuff" relating to that installation itself, and for this type of problem the stray current goes away when you open breakers and remove meters. This type of stray is usually attributable to a genuine fault (ie something has gone wrong and it can be fixed to make the problem go away), or by less than good design, but a design still in full compliance of the NEC.

The other is type unaffected by breakers and meters, and is still present when the meter is missing, the disco off and all the breakers open, and you've ripped the hots off the weatherhead. I call this type "ground versus ground" leakage. For this category, the currents are sourced from outside of the immediate installation, often attributable to voltage drop along an MGN between poles and transformers. There is no fault to be fixed for this type of problem, it is a feature rather than a fault. You have to "work around" the problem.

I agree with these two sources of voltage on the service neutral/grounding, but are they really that different? the voltage is real just as the voltage we measure from a secondary hot and Earth is real, the only thing that has changed is the source of the voltage, the voltage is still being brought in to the premises grounding through the service neutral, which if it were removed from the terminal in the meter or at the transformer (which as I said before is not the thing to do), this voltage would also be removed, this would show that it is not the Earth that has voltage on it, but that the grounding of the premise that has the voltage on it.
 
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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
100709-0834 EST

Larry:

Very good. Hopefully this will help others get an insight into some general concepts.


hurk27:

I created a very controlled experiment in my example so as to obtain a uniform current density to demonstrate a concept that with two voltage probes spaced a short distance apart you can estimate the direction of current flow in the earth.

When you have point sources or line sources and you want to calculate the voltage or current distribution, then you need to create field maps. We spent a whole half semester in A. D. Moore's class hand sketching various field maps, two dimensional, of various geometries.

Even though the major voltage drop around a vertical ground rod occurs close to the rod I can estimate the directional location of that rod at some distance from the rod with two probes and a voltmeter.

.
 

hurk27

Senior Member
While A.D. More was a great pioneer in electro static research and most of his work was written down in a very easy to understand scrips, and he did do many experiments on electrostatic fields upon the Earth, much of this was done using electro-static generators which product very high voltage products with a very high frequency by-products, this in no way will behave in the same manner as dynamic current will in the Earth, one thing is because of the high frequency nature of electro-static current will tend to follow the surface of the conductor, I.E. Earth, and this will tend to cause straight line paths between two points, but dynamic current will not, as in the many experiments will show it will follow all paths between two points, so while your thinking is right on with electro-static energy, dynamic current will not act in this way. fundamentals of what we now know about lightning can be based upon some of Mores work.
 
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