Paralleled service neutrals

[karl riley]

I was called to do an EMF survey of a house where an average of about 2.5 amps of neutral was running through the grounding electrode conductor to the water service pipe. The conductor path took it under a child's bedroom where a four-hour data logging showed a magnetic field average of 4.6 Mg. This was a concern since the WHO has verified that large studies show a doubling of childhood lekemia at 4 mG and above. A current of 5 amps produces a magnetic field of 10 mG at one meter from the conductor.

This is just an introduction to my real question: there are two main panels in the basement. They are bonded by a conductor between their grounding busses. The neutral and grounding busses are bonded in both panels. Thus the neutral current is paralleled back to the meter box. So it seems that the hots are not paralleled but the neutrals are. Any comments? The maximum net currents on the two service cables measured between a 19 amps and 15 amps.

One GEC from one panel goes to the ground rod outside, and the GEC from the other panel goes to ther water pipe clamp.

Karl

 

[bob]

This is just an introduction to my real question: there are two main panels in the basement. They are bonded by a conductor between their grounding busses. The neutral and grounding busses are bonded in both panels.

You know the rule. The neutral and GEC are bonded only at the main switch.
Do the panels both "tap" the service conductors and have a main Sw?

Thus the neutral current is paralleled back to the meter box. So it seems that the hots are not paralleled but the neutrals are. Any comments? The maximum net currents on the two service cables measured between a 19 amps and 15 amps.One GEC from one panel goes to the ground rod outside, and the GEC from the other panel goes to the water pipe clamp

Does the service have a neutral and GC or 2 neutrals? If not, I do not see how the "neutral current is paralleled back to the meter".
Most installation have a GEC to the gnd rod then to the water pipe or vise versa. Electrically this installation is the same. The 2.5 amps are not necessarily
from this load. Some of it could be from a neighbors load returning to the utility. You can pull the meter and find out.

 

[karl riley]

Each of these twin panels are fed by 2 hots and a neutral. The neutrals and grounds are bonded in each. Each has a main switch. At the bottom of the panels a bonding conductor runs between panels, from the grounding busses. Thus the neutral is paralleled but the hots are not.

I haven't seen this before, where the neutrals are paralleled but not the hots.

Yes, the neutral traveling on the water pipes can be coming from a neighboring service as well as from this service. When the mains are open there is still some current on the neutral. Of course it is always fluctuating.

Karl

 

[roger]

At the bottom of the panels a bonding conductor runs between panels, from the grounding busses.
Karl

Karl, why not just remove this conductor, it appears to me this is the root of the problem.

As far as the GEC, it should be from only one panel or the meter and all the other GE's should be jumpered to this (first) GE to form the required GES.

I know the NEC and Soars say it's okay to do it other ways, but it seems to me that is just asking for problems.

Roger

 

[ramsy]

Each of these twin panels are fed by 2 hots and a neutral. The neutrals and grounds are bonded in each. Each has a main switch.

If there's a svc.disconnect or meter socket before these panels, isn't that where the neutral should be bonded, not in load-side panels? NEC 250.24(A)5.

..a four-hour data logging showed a magnetic field average of 4.6 Mg.

Karl, what instrument was used to measure EMF @ 4.6 Mg in the childs bedroom? If calculated from an energized bonding path under the floor, don't forget all EM energy is an inverse-square, the magnitude is halved for each diameter of distance away from the source.

A 1" pipe measured @ 4.6 Mg, in a crawl space below, would be 0.46 Mg 10 inches away (10 times weeker), and the bedroom floor may be > 1ft above that pipe.

 

[roger]

Ramsey, I think Karl Riley has a pretty good understanding of EMF's

Roger

 

[karl riley]

Roger R., magnetic field strength from a single conductor weakens directly with distance, not by the square. The field from a full circuit, including power lines, weakens with the square of the distance, as long as there is no net current from neutral traveling in other paths. The field from "point" sources such as transformers weakens with the cube of the distance.

Net current also weakens directly with distance. In the case of this house, the amps that are on the water pipe give to the service cable that same amperage as net current. In other words, the neutral is robbed of part of its balancing current, or in the case where a neighbor's neutral is coming in and using your service cable to get back to the transformer, it would be an excess of neutral.

Roger, yes I believe the GECs should have originated outside at the meter box. But given what is there, I guess what I am asking is whether the NEC allows two service entrance cables landing in two service entrance panels to have paralleled neutrals. I don't usually deal with these questions as an EMF consultant, and I was not authorized to make changes. I am mainly curious.

Karl

 

[karl riley]

About the data logging gaussmeter that was used: it is the EMDEX Mate made by Enertech in CA. In the four hours it collected 28,808 measurements. It not only gives you max, min and average. It gives the standard deviation as well as the percentage of measurements in each category of under 0.5, under 1, under 2, under 5 (mG) etc. Though the average was 4.6 mG, the max was 10.3 mG.

Karl

 

[ramsy]

..whether the NEC allows two service entrance cables landing in two service entrance panels to have paralleled neutrals.

Arn't parallel neutrals 300-3(A)1, > #1, OK if not objectionable paths (not using EGC or GEC). 250.6(A-B)?

Karl, many thanks for the EM details. Never thought there was any difference in how those fields weaken.

 

[George Stolz]

I think the configuration is legal but shouldn't be.

I'd remove the conductor between, and reroute the GEC to the ground rod to the panel containing the GEC for the water pipe. Done.

Although (as I slide on my devil's advocate hat):

Could it be argued that 250.24(A)(1) is calling for an individual point where the grounding electrodes are connected to the service? So connecting in two seperate handles of the service could be illegal?

Could this really be called a "parallel neutral", and illegal by 310.4?

 

[bob]

Roger R., magnetic field strength from a single conductor weakens directly with distance, not by the square. The field from a full circuit, including power lines, weakens with the square of the distance, as long as there is no net current from neutral traveling in other paths. The field from "point" sources such as transformers weakens with the cube of the distance.Karl

Karl I am not an expert in this area but I do not understand why field strength weakens at different distances for different sources. I did a little google searching and several articles indicated that the strength decreases with the sq. of the distance from the source.

 

[ramsy]

I think Bob's onto something here.

The field from "point" sources such as transformers weakens with the cube of the distance.

If Karl was being facetious, then he's a sick man. Almost as sick as Mr. hot-pepper roger, "Hot lips".

Ramsey, I think Karl Riley has a pretty good understanding of EMF's

This "Karl Riley" URL is a store front for Magnetic Sciences; no sign of Karl, unless he works there, and I doubt that.

 

[roger]

ramsey, you're up to late, you must be drinking. Scroll down the page to the Books and DVD's. It must be the smoke in your eyes.

No sign of Karl uhh?

"Tracing EMFs in Building, Wiring and Grounding" book by Karl Riley
"Tracing Magnetic Fields in Building Wiring[FONT=Helvetica, Arial, sans-serif]" DVD or video by Karl Riley[/FONT][FONT=Helvetica, Arial, sans-serif]


[/FONT]
Roger

 

[roger]

I think Bob's onto something here.If Karl was being facetious, then he's a sick man. Almost as sick as Mr. hot-pepper roger, "Hot lips". This "Karl Riley" URL is a store front for Magnetic Sciences; no sign of Karl, unless he works there, and I doubt that.

BTW, I don't think Karl was being facetious, and I don't mind being in Karls sick company.

Roger

 

[ramsy]

I think the configuration is legal but shouldn't be. I'd remove the conductor between (panels)

George we might want to see this installation for ourselves. If we found a disconnect in that meter box outside, and more than a few inside feet of SE cable feeding one of those inside panels, it would be considered a sub panel. If so, those panels would need an EGC between them.

 

[ramsy]

ramsey, you're up to late, you must be drinking. Scroll down the page to the Books ..No sign of Karl uhh?
"Tracing EMFs in Building, Wiring and Grounding" book by Karl Riley
"Tracing Magnetic Fields in Building Wiring[FONT=Helvetica, Arial, sans-serif]" DVD or video by Karl Riley[/FONT][FONT=Helvetica, Arial, sans-serif][/FONT]

Wow, am I relieved. LMAOL. Thought you & Karl were really pullin my leg.

The instrument Karl described wasn't one from "Magnetic Sciences," and fields weakening with "the cube of the distance" sounded prety ridiculous. No offense to Karl, but I think I "will" have a few drinks now.

 

[karl riley]

I woke up this morning to see all these interesting posts. I will try to clear them up.

I discovered the rates of weakening of the 3 types of magnetic field sources by repeated measurements. Measurements don't lie. Later I found that these rates were verified and understood by electrical engineers who had experience with measuring magnetic fields. I also found that a lot of engineers and electricians had misinformation in their heads that had assumed the proportions of reality, such as you see in some of these posts.

Early on I set up laboratory conditions to make very exact measurements of these conditions. As a consultant I use the rate of weakening to help identify the sources. The "point" source is actually a coil source such as a transformer or motor. So a small coil like a plug-in transformer gives you a neat weakening by the cube of the distance. Dimmer switches are typical for this.

A large power transformer weakens by the square when you are close to it and by the time you are out about 8' or so it shows the cube weakening from then on. Power lines show the square rate but when some of their neutral is traveling in the earth or water pipes there is a net current component so that part of the field is weakening directly with distance. As you get farther out the square component fades out and the net current component is still there.

So I would advise any sceptics to get a gaussmeter and start measuring. There is nothing like reality to chase away presumptions.

About Magnetic Sciences. I formed this company when I designed, manufactured and marketed the MSI single-axis gaussmeters and their sensors. I also retailed a few other gaussmeters that I had tested and found accurate. I finally sold the business to a friend. I continue consulting under the name of ELF Magnetic Surveys.

The Emdex meter is produced by Enertech. Their Emdex II has been a favorite of the Utilities for decades.

I am still uncertain about that double set of service entrance panels that I also believe should have been treated as sub-panels. Maybe I will start a new thread under Grounding and Bonding and try to keep my question simple.

Karl

 

[ramsy]

So I would advise any sceptics to get a gaussmeter and start measuring.

I would not be entirely surprized with discrepecies between actual measurements and conventional wisdom.

I believe conventional electric-theory text books have taught for years that current flows from - to + in a DC circuit, regardless of later measurements showing the opposite.

Anyone who invests an effort in measurement and proof may have more influence with reproduced and peer reviewed evidence, but that process may not always change conventional wisdom.

Karl, many thanks for translating this effort so I could understand it, and for sharing what must be a substantial investment in time and original work with EM measurements.

 

[karl riley]

Ramsy, you are most welcome. I learn more from this forum than I contribute.
Karl

 

[karl riley]

I am looking at these posts again since there were so many good ideas. George, you asked if the neutral going back to the Tfrmr by the water pipe path could be considered a parralel neutral and so violate 310-4.

I thought about this too. It's an unusual situation. One parallel conductor, the GEC and the section of the water pipe inside the house would be under the NEC. The other conductor is in the SEC which is under Utility control. So could we make a case that the NEC paralleled conductor is disallowed since it is under NEC control? It certainly violates 310-4.

Karl