City water network creates parallel neutrals (parallel conductors)

[EMFExplorer]

I don't know anything about "ghosts" Not my field lol.

Everything we do is AC magnetic fields. K&T as you mention is usually horrendous since the conductors are so far apart. All current will cause some fields since the conductors can't physically occupy the same physical space. But when the conductors are right next to each other in NM for example (well almost, sometimes the ground in the middle) they are pretty small.

When a load on a cable isn't balanced, then the fields cover a large area. Or if you want to look at it another way, the fields are much "stronger" - the readings are much higher. Fields from balanced cables/conduit drop off very rapidly. Fields from unbalanced cables/conduit do not drop off rapidly as you move the meter away from them.

This is the problem with the water pipe bonding...it creates an imbalance on the electrical service, the wire going to the pipe, and the pipe itself all the way back out to the street. There is an imbalance everywhere and a field everywhere. Break the pipe and all of that disappears instantly. No more transformer effect.

 

[don_resqcapt19]

A number of us have been bringing this issue to light for some time. When a home or other building is connected to city water via copper water supply pipe, and the electrical service is bonded to this pipe, the pipe becomes a secondary neutral current-carrying conductor. Rather than just be present in the temporary event of a fault, it is actually a current-carrying conductor that is operating 24/7/365.

It is my opinion this is very inappropriate and actually violates sections of the NEC. Yet it is also required. I think the code should be updated, and it should be standard practice to electrically isolate the city water network and only use ground rods or other electrodes. When we interconnect all buildings via the water, we create countless paths for circuit current to take that are NOT along the appropriate path - the intended circuit current-carrying conductors - wherein the current should be confined. Using pipes for carrying circuit current should be prohibited.

There have been a number of proposals to prohibit the use of the metal underground water pipe as a grounding electrode, but they have all been rejected by CMP5. The best way to make a change is via the plumbing code requiring a section of non-metallic pipe before the water service enters the building.

 

[wwhitney]

That is true, but it will return based on impedence of each path with more allocated toward the lower impedence in ratio to the impedence of each.

Precisely.

So let's say you're in a city with 3/4" copper type K water laterals, and a metal water main. The water main will be ferrous, but quite large, so let's make the guess that its resistance per foot is comparable to the 3/4" copper. 3/4" copper type K has an OD of 0.875" and an ID of 0.745". That means it's equivalent in cross-sectional area to a conductor of diameter sqrt(0.875²-0.745²) = 0.459". That's a 4/0 Cu conductor!

Take a worst case where all the plumbing joints have low electrical resistance, and let's assume the distance from the house to the water main is the same as from the house to the POCO transformer. If you share a transformer with two neighbors, now there are 3 parallel paths for your grounded service conductor current: through your service, and through 2 lengths of 4/0 Cu equivalent to a neighbor's service, times two.

I doubt for a residence the grounded service conductor will be a 4/0 Cu conductor, let's call it a 1/0 Cu conductor for ease of computation (1/2 the cross-sectional area, so twice the resistance). Then the 3 paths have relative resistances of 2, 4, and 4. That means the total relative resistance is 1, and half the current goes through your grounded service conductor, a quarter through each of your neighbors. For the case that each of them has no grounded service conductor current of their own.

Obviously I made a bunch of assumptions in this example, but it does show that the water pipe parallel paths can easily carry a big fraction of the grounded service current.

Cheers, Wayne

 

[Geber]

Metallic water systems are becoming rare so not much of a concern anymore but here is an illustration to go with your post.

View attachment 2570070
Please update your profile to include a little more accurate location.

This diagram would be equally true even if the neutral in the service drop to house 1 were not open, if the potential on the neutral in house 1 were a little higher than in the other houses.

 

[petersonra]

I looked his web site. He sells stetzer.

His web site also says this:

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But you can protect your family
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[rambojoe]

neutral current on the primary side of the transformer? What's your question?

How and where do you measure neutral current on the primary side of a utility transformer? Fair question...

 

[EMFExplorer]

How and where do you measure neutral current on the primary side of a utility transformer? Fair question...

I do not measure current on the primary side of a utility transformer. I don't measure current at a utility transformer, period, with the exception of conduit in which case I would be measuring the entire conduit for an imbalance in current.

Forgive me for not understanding your question. Just as there is current on the secondary side on the grounded and ungrounded conductors, there is also current on the primary side on the grounded and ungrounded conductors. It is measurable in amps/milliamps.

 

[jaggedben]

I do not measure current on the primary side of a utility transformer. I don't measure current at a utility transformer, period, with the exception of conduit in which case I would be measuring the entire conduit for an imbalance in current.

Forgive me for not understanding your question. Just as there is current on the secondary side on the grounded and ungrounded conductors, there is also current on the primary side on the grounded and ungrounded conductors. It is measurable in amps/milliamps.

Neutral current flowing on parallel ground paths on the secondary of side of a utility transformer does not say anything about whether primary current flows through the ground. Primary and secondary are galvanically isolated.

 

[jaggedben]

..

It is my opinion this is very inappropriate and actually violates sections of the NEC. ...

Actually the NEC is quite carefully written such that current flowing through grounding electrodes is not a violation. Avoiding current flowing through the ground (and therefore metal pathways underground) is also fundamentally inconsistent with the idea of grounding electrical systems. Grounding electrical systems is a very strong tradition in this country and NEC rules and all the rules around most electrical safety devices in this country are built around it. It's not a simple change you're asking for.

When we interconnect all buildings via the water, we create countless paths for circuit current to take that are NOT along the appropriate path

The paths on a metal water distribution network might save one house with an open neutral from burning down for every plumber they expose to a shock hazard. It's a tradeoff, in my opinion.

I think the code should be updated, ...

BTW, instead of changing the NEC why not make it mandatory for plumbing codes to install a dielectric connection to the house. Even if the NEC removed the requirement to use the metallic water piping as part of the GES it would still be connected due to inside bonding be it purposely or accidental.

I agree with Roger that this would be better addressed by the plumbing code. However, the dielectric connection creates the potential for a shock hazard across the union if not all of the houses connected to the utility transformer get updated at the same time.

 

[jaggedben]

A properly operating and installed system should not be putting any primary/secondary current onto the GES of a structure.

That is not correct with respect to secondary current from a utility distribution transformer.

 

[don_resqcapt19]

Neutral current flowing on parallel ground paths on the secondary of side of a utility transformer does not say anything about whether primary current flows through the ground. Primary and secondary are galvanically isolated.

The utility primary neutral conductor to a transformer and the secondary neutral conductor are physically connected to each other at the transformers. Often with single phase line to neutral transformers, the utility will use a single conductor as both the primary and secondary netural.

 

[rambojoe]

Forgive me for not understanding your question. Just as there is current on the secondary side on the grounded and ungrounded conductors, there is also current on the primary side on the grounded and ungrounded conductors. It is measurable in amps/milliamps.

if you never measure grounded conductors installed by the utility, how would one know its there? Even if its a neligable amount of milliamps?
I got from the other posts the reference to primary and secondary... just wondering.

 

[LarryFine]

I think of the MGN and the local metallic water piping as a large grounding mat or grid.

It collectively defines the grounded distribution system neutral and zero-volts reference.

Currents within that grid are largely unavoidable and, in a way, are none of our business.

These thoughts are all based on an intact service neutral conductor and current pathway.