Objectionable Current - Water main

[don_resqcapt19]

Right but in practice 99.9% of buildings will have rebar, so either the concrete people will end up doing electrical work or the electrician will end up doing concrete work.

Anyway, I don't see a statement about prohibiting neutral current flowing on piping systems to be in conflict with anything in 90.2 if they wanted to, which they don't because the organization is too far gone and a lost cause.

But the NEC could not require rebar to be installed in a footing to create a concrete encased electrode. They could require a copper wire to be placed in the concrete to be used as an electrode, but the code has not done that.

The installation of the rebar is not electrical work. The only electrical work with when you have re-bar used as a concrete encased electrode is the connection of the grounding electrode conductor to the re-bar and that is typically done by the electrician.

There are plenty of ways the code could be written to get rid of objectionable current without writing rules that are outside of the scope of the NEC.

 

[don_resqcapt19]

It also requires to use 10 feet or more of underground water piping as an electrode. So if the plumber were to put an isolating fitting between interior and exterior piping NEC would still require us to bond to both.

In my opinion, if the isolation fitting is on the street side of the water service entry to the building there would be no required GEC connection to that water pipe. There would be the required interior bonding if there is a metallic water piping system in the building.

 

[LarryFine]

In my opinion, if the isolation fitting is on the street side of the water service entry to the building there would be no required GEC connection to that water pipe. There would be the required interior bonding if there is a metallic water piping system in the building.

Don't forget that even things like well casings on the property are supposed to be bonded.

 

[don_resqcapt19]

Don't forget that even things like well casings on the property are supposed to be bonded.

Not bonded...the well casing must be used as a grounding electrode if it is metallic.

 

[LarryFine]

Not bonded...the well casing must be used as a grounding electrode if it is metallic.

That's what I meant.

 

[W@ttson]

If the problem is caused be current flowing along the pipe, and if there is a break in the pipe (say some sort of dielectric union is already present), then bonding around that break will remove the hazard. But you have not yet determined that this specific scenario is causing the problem.

My hunch is that there is current flowing in the soil from some source, and the pipes are creating concentrated regions of step potential. You will need to locate and correct the source of this soil current, or you will need to do major work to alter the shape of the step potential field. But that is a hunch, not a definite answer.

I'm with Hal. You need to measure what is happening before you try to fix anything.

Jonathan

So this seems to be similar to the Stray Voltage that Mike holt was talking about in his Stray Voltage video where he references he was on the Stray voltage foundation.

 

[W@ttson]

A band-aid solution might be equipotential bonding around the pipes, installing a tapering ground grid so that the soil near the pipes is bonded to them. However this just pushes the problem away from the pipes, it doesn't solve the problem.

Essentially 547.10 Equipotential planes that are used in agricultural buildings to mitigate the Neutral to Earth Voltage that livestock feel.

 

[W@ttson]

So I gather the following, and without testing its all a guess:

1. The pipe could be carrying current back to the source. This generally is not an issue, however, if there are disjointed portions of pipe or high resistance parts, there could be a voltage potential difference there and if someone touched the two separate sections, they could be a shock. Similar to disconnecting a home water pipe to change a meter.
   1. Solution would be to to bond across the full length of exposed pipe. Or more unrealistically, see where the objectionable current is coming from from one of the nearby electrical installations and correct it to have the current flow back on the neutral, not the back up neutral - the water pipe.
2. The water main is actually energized. Like how light poles could have a loose phase conductor come off and make contact with the pole. If that pole is not bonded by an EGC that pole can be energized.
   1. Solution would be to locate how that water pipe is being energized and correct it. Water pipe can also be bonded by an EGC from the local utility though I am not really sure how that will work since there is no OCPD on the utility end of things. This whole working outside of the electrical premises muddies things up nicely.
3. The same issue that livestock have and for the issues that Mike Holt explained in his "Stray Voltage" video which for some reason is now set to "Private", people can feel quite a bit of discomfort from even 2-3V of potential difference. He went on to talk about a case study where a gentleman called him to his house because he would be getting shocked when sitting on the pool concrete deck and putting his feet into the water. The reasoning is since there is a Neutral to Earth voltage potential, the earth is at 0V but the Neutral, and therefore, the bonded electrical entities on ones premises are at the potential higher, the NEV voltage. This could be a large range and it is constantly varying based on the load in the neighborhood. This pipe could be having a similar effect where the nearby earth is at 0V but this pipe is at some NEV potential difference.
   1. The solution to this is to bring everything to the same potential. Essentially, make us into the bird that can sit on the high voltage lines. If we do not have a potential difference, we can't get shocked. This would entail created a ground grid around the pipe, and then taper away from it with a voltage ramp, just like for livestock. Here is a sample of such a voltage ramp from one of Mike Holt's references.
   2. 
4. On the flip side, and on the same chain of though as number 3 above, it could be that the nearby utility phase conductor has deteriorated, and leaking current to ground. This will cause the same potential gradients as are present from the NEV instance. Except the difference is that the neutral is not causing the voltage drop and therefore the potential difference, but it would be the voltage drop through the earths resistance from the phase conductor being directly connected to it. This would create step potentials. The waterline being the mix of things, would bring these step potentials to the surface - pun intended.
   1. Solution would be to open up the electrical underground vault which is about 75ft from this waterline and investigate the condition of the transformers and the conductors in there. This is likely the first thing that should be done as is the most likely culprit of why someone may be getting a shock when touching this exposed above ground water main. If the transformers and the conductors are in poor shape, replace them. Replace feeders to the customers that they serve.

Please let me know if I am off with my train of thought on 1-4 above.

 

[winnie]

I think you have a good list of possibilities.

IMHO the first testing should be to stick probes into the ground and measure the voltage between points points on the surface and the piping system.

You will need to measure both AC and DC voltage.

Let us know how it turns out.

-Jonathan

 

[garbo]

Beating a dead horse because I posted this concern a year or so ago. In my big city Exelon only runs one high voltage wire ( usually from 13.2 KV line ) so with the other side of primary is connected to grounded transformer case and center tap ( neutral ) of the 120 / 240 volt secondary I have found over 0.25 amps current flow on copper water services and steel pipe for natural gas service. Even when Exelon had three phase 13.2 KV on top of a pole they still only use one primary wire. My feeling is if they feed the primary of transformer with two wires current flow on every houses water & gas pipes if not eliminated would be greatly reduced. Like I previously posted I have measured over 0.25 amps travel back thru a copper water service with the meter pulled. Now that's its warm I plan to measure current on the ground rod running from a few transformers. Here in my large concrete jungle of a city where pole ground rods have a concrete / paved streets do not have any bare ( grass ) ground area with a 20' diameter doubt if ground rod resistance is even close to 250 ohms especially in the winter. Can remember one of my talented Vo Tech shop teacher telling us that the Brooklyn had over a hundred amps of current flowing thru it.

 

[kwired]

In my opinion, if the isolation fitting is on the street side of the water service entry to the building there would be no required GEC connection to that water pipe. There would be the required interior bonding if there is a metallic water piping system in the building.

How is this any different than requiring a bonding jumper around a water meter, water softener or any other isolating components?

If the isolating fitting were outside the building then I can see there not being a qualifying electrode present, yes interior piping still needs bonded if it is a metallic system.

 

[electrofelon]

Beating a dead horse because I posted this concern a year or so ago. In my big city Exelon only runs one high voltage wire ( usually from 13.2 KV line ) so with the other side of primary is connected to grounded transformer case and center tap ( neutral ) of the 120 / 240 volt secondary I have found over 0.25 amps current flow on copper water services and steel pipe for natural gas service. Even when Exelon had three phase 13.2 KV on top of a pole they still only use one primary wire. My feeling is if they feed the primary of transformer with two wires current flow on every houses water & gas pipes if not eliminated would be greatly reduced. Like I previously posted I have measured over 0.25 amps travel back thru a copper water service with the meter pulled. Now that's its warm I plan to measure current on the ground rod running from a few transformers. Here in my large concrete jungle of a city where pole ground rods have a concrete / paved streets do not have any bare ( grass ) ground area with a 20' diameter doubt if ground rod resistance is even close to 250 ohms especially in the winter. Can remember one of my talented Vo Tech shop teacher telling us that the Brooklyn had over a hundred amps of current flowing thru it.

Like I said before, getting rid of the MGN won't fix that, you would need to supply each premise with a dedicated transformer.

 

[don_resqcapt19]

Beating a dead horse because I posted this concern a year or so ago. In my big city Exelon only runs one high voltage wire ( usually from 13.2 KV line ) so with the other side of primary is connected to grounded transformer case and center tap ( neutral ) of the 120 / 240 volt secondary I have found over 0.25 amps current flow on copper water services and steel pipe for natural gas service. Even when Exelon had three phase 13.2 KV on top of a pole they still only use one primary wire. My feeling is if they feed the primary of transformer with two wires current flow on every houses water & gas pipes if not eliminated would be greatly reduced. Like I previously posted I have measured over 0.25 amps travel back thru a copper water service with the meter pulled. Now that's its warm I plan to measure current on the ground rod running from a few transformers. Here in my large concrete jungle of a city where pole ground rods have a concrete / paved streets do not have any bare ( grass ) ground area with a 20' diameter doubt if ground rod resistance is even close to 250 ohms especially in the winter. Can remember one of my talented Vo Tech shop teacher telling us that the Brooklyn had over a hundred amps of current flowing thru it.

Would be interesting to find out. It would be my opinion that most of the current on the water pipe is from the parallel paths on the low voltage side of the transformer.
Not sure why there would be current on the gas line. The gas utility has been using an isolating fitting on the street side of their gas meters in this area for many many decades.

However with both gas and water there is almost no metallic piping being installed around here. Even high pressure gas, up to 600 PSI is run in PE pipe.

 

[LarryFine]

Not bonded...the well casing must be used as a grounding electrode if it is metallic.

I should have said "bonded to" as an electrode.

 

[garbo]

Would be interesting to find out. It would be my opinion that most of the current on the water pipe is from the parallel paths on the low voltage side of the transformer.
Not sure why there would be current on the gas line. The gas utility has been using an isolating fitting on the street side of their gas meters in this area for many many decades.

However with both gas and water there is almost no metallic piping being installed around here. Even high pressure gas, up to 600 PSI is run in PE pipe.

In my area all of the houses older then maybe twenty years old have gas meters installed I doors with no isolation fitting. When I cut & threaded a few pieces of 3/4" steel gas pipes to my new furnace I went to a local plumbing supply house and asked for a 3/4" insulating union. First they told me they did not have the female by female type but have female fitting with one side and male pipe threads on other side but that also was out of stock so just reused the 3/4" union. Houses on my block were built in 1964 and less then10 years later the underground steel pipe to 6" main ( believe it or not is located under our sidewalk ) started to leak. They pulled a plastic pipe thru leaking steel pipe. Have to dust off my 600 amp Amprobe to take a measurement kenny gas service. While talking about gas furnaces at an IAEI meeting years ago somebody asked if there is a canvas sound isolation section that air passes from heater to main supply metal duct work should or must this be bonded. NEC does state something like anything that be energised should be bonded.

 

[LarryFine]

NEC does state something like anything that be energised should be bonded.

Not can be, but likely to be, which is usually covered by the EGC of the source.

 

[garbo]

Not can be, but likely to be, which is usually covered by the EGC of the source.

Somebody asked if the kitchen sink was metal with plastic waste line & PEX water lines with or without a garbage disposal must the metal sink be bonded. Think it must be bonded but would be best if the sink came with a threaded stud or other means to provide a reliable low resistance connection. For bathtubs with a whirlpool would go the extra mile and run the solid copper wire from the cold copper line to the motor then to hot water line to metal drain pipe then back to the cold copper line. That way if this wire somehow broke or got disconnected motor would still be bonded.

 

[retirede]

Somebody asked if the kitchen sink was metal with plastic waste line & PEX water lines with or without a garbage disposal must the metal sink be bonded. Think it must be bonded but would be best if the sink came with a threaded stud or other means to provide a reliable low resistance connection. For bathtubs with a whirlpool would go the extra mile and run the solid copper wire from the cold copper line to the motor then to hot water line to metal drain pipe then back to the cold copper line. That way if this wire somehow broke or got disconnected motor would still be bonded.

IMO, a kitchen sink is not “likely to be energized.”

 

[don_resqcapt19]

from the NFPA NEC Style Manual.

"likely to become energized -- failure of insulation on"

That would mean you would have to have electrical equipment or wiring in contact with the object so that if the insulation on the equipment or wiring fails the object could become energized.

 

[garbo]

IMO, a kitchen sink is not “likely to be energized.”

Thought the same thing but if a toaster,coffee pot etc ( even with short cords ) on a GFCI protected circuit thought the GFCI would have a faster response time if sink was bonded. If a toaster that was plugged in but not on being they only have a two wire male plug ( no ground wire ) the GFCI might not trip and sink could be energised.