Grounding

[dnem]

I am curious now, in your opinion what does violate 250-32(B)(2) #(2)?

There's several different things being discussed here.

First, your question. . I don't doubt that a communication jacket bonded at both ends is a "continuous metalic path bonded to the grounding system in each building or structure involved". . What I'm saying is that I'm not willing to be the only inspector in northern Ohio that applies 250.32(B)(2) to communication wiring. . I haven't met an Ohio inspector yet that applies a communication jacket to 250.32(B)(2).

Another item discussed is multiple bonding of the current carrying grounded conductor instead of also having a separate fault current only equipment grounding conductor.

I believe an equipment ground always results in a better safer installation. . But I don't believe that all installations have the same cost vs benefit. . There are broad categories that have very different cost/benefit balances.

I would list the broad categories as:
1] inside
2] separate buildings/structures both on the same SDS
3] line side of the service but still load side of the SDS/utility transformer
4] line/utility/primary side of the SDS/utility transformer that supplies a service

As far as #4] goes, I don't see enough benefit to adding a fault current only conductor on utility runs that go from transformer to transformer. . Running it down the street would be extremely expensive and your current carrying grounded conductor potential to ground would increase significantly as you travel miles away from the single bonding point [which would undoubtedly be at the secondary of the supplying transformer at the substation.]

As far as #3] goes, running an equipment ground from the top of the pole or ground resting transformer that supplies the service to the building isn't a bad idea but it would add considerable expense to some large and long service laterals plus you would have to reach beyond the NEC to get it required. . That'll get into utility "turf" and they are going to be dead set against it.

As far as #2] goes, 250.32(B)(2) is gone for new installations and I don't disagree with that decision to get rid of it. . My only point was that it isn't as critical as requiring an equipment ground inside a building.

As far as #1] goes, we crossed that bridge a long time ago. . The only remnant is replacing existing stuff that never had an equipment ground.

So now that 250.32(B)(2) is gone, 250.32(B) looks alot like 406.3(D)(3). . The elimination of 250.32(B)(2) was a good change but the requirement of an equipment ground inside a building is more important and more of a safety issue than the building to building.

David

 

[M. D.]

I know this is a little off topic but someone raised article 547 ,this is just a bit of the proposal ,.. it was rejected . 547.10 is also a good read,. in my opinion.​

Report on Proposals A2007

? Copyright, NFPA NFPA 70

19-5 Log #2418 NEC-P19​

Final Action: Reject​

(547.2)​

____________________________________________________________​

Submitter: ​

​

Donald W. Zipse, Zipse Electrical Engineering, Inc.​

Recommendation: ​

Delete definition for Equipotential Plane.​

Substantiation: ​

For additional substantiation, please read also 547.10​

Proposal.
​

​

​

​

The definition of ?equipotential plane? is a complete misunderstanding
and misconception as there is​

​

no such item as an equipotential plane that​

prevents a difference in voltage from developing within the plane.
​

​

Ohm?s Law states that​

​

Voltage = Current X Resistance​

Unless the buried in concrete metal mesh is at or near absolute zero

temperature, the mesh will have some resistance. Any current flowing over and
through the mesh will produce a voltage per Ohm?s Law. This has been proven
by testing as will be described below.
Cow Contact (cc) is defined as any two places on a cow that can encounter
an energized ?conductor? or conducting surface. For example, a cow drinking
from a water trough that is energized standing on the earth would have a
cow contact from the water through the tongue through the legs to the earth
completing part of the circuit.
With the approval of Code Making Panel # 5?s acceptance of the dangerous
and hazardous multigrounded neutral distribution system, stray current has
been measured flowing within dairies.........

......The Electric Power Research Institute (EPRI) an organization of utilities companies states that 40 to 60 percent of the return neutral current from the high voltage electrical circuit returns over or through the earth. We have measured as high as eighty-eight (88) percent of the neutral current returning over the earth and thus through the dairy, back yards of homes through hot
tubs, swimming pools, etc.
Mr. Lawrence C Neubauer has conducted investigations and has measured
stray current in over 600 ? 800 dairies. To prove there is a voltage in an
equipotential plane Mr. Neubauer took a large plastic container, which is an
insulator. He placed a coil of bare copper under the bucket in intimate contact
with the concrete. Next, he placed a coil of copper in the bottom of the plastic
bucket. A milliammeter was connected between the coil in the bottom of the
bucket and the coil of copper ?connected? to the concrete holding area where
the equipotential plane had been installed.
The plastic bucket was filled with water. As the cows entered they attempted
to drink out of the plastic bucket, however, it was evident they received an
electrical shock as they jerked their heads out of the water. When two or more
cows drank the voltage divided between the cows and they continued to drink
The electrical circuit was from the equipotential, which supposedly prevents
a difference in voltage from developing, up the legs of the cow, through
the body to the tongue, into the water, through the copper in to bottom of
the plastic bucket, to the milliammeter and finally to the copper which is in
intimate contact with the concrete equipotential plane. Readings of over a
milliamp were recorded on VHS.....​

.......​

.........THERE IS NO BENEFIT IN ANY WAY, SHAPE

OR FORM FROM EQUIPOTENTIAL PLANES, ONLY HARM. ​

The​

concept was based on erroneous ideas and conclusions and mis-understanding

of electrical principles.​

​

​

The dairy farmers in Wisconsin long ago deleted from the state adopted​

NEC the sections on equipotential planes as they realized the danger and
hazards equipotential planes presented to dairy farmers. Now if only the
WI PUC was as smart.​

​

​

____________________________________________________________​

​

​

​

​

​

 

[M. D.]

From the Rocky Mountain chapter IAEI

1. I have a detached garage served by common service from dwelling. I have a phone wire installed between the two buildings. Am I required an equipment grounding wire to be installed with the feeder from the dwelling to the accessory building?

Panel Response: Yes, Article 250.32(B)(2) permits using a feeder without an equipment ground only where there are no continuous metallic paths, such as the one likely presented by the phone line.

 

[M. D.]

....First, your question. . I don't doubt that a communication jacket bonded at both ends is a "continuous metalic path bonded to the grounding system in each building or structure involved". . What I'm saying is that I'm not willing to be the only inspector in northern Ohio that applies 250.32(B)(2) to communication wiring. . I haven't met an Ohio inspector yet that applies a communication jacket to 250.32(B)(2).


David

David I'm not sure what to make of these statements ,... I give you credit for the honesty of them though

 

[dnem]

M.D.

In your post of the ROP about deleting the equipotential plane, it stated in the conclusion:

"The dairy farmers in Wisconsin long ago deleted from the state adopted NEC the sections on equipotential planes as they realized the danger and
hazards equipotential planes presented to dairy farmers"

Am I drawing the right conclusion that the claim is that the equipotential plane is creating a lower resistance/impedance path than the earth itself for the unbalanced current that the utility is dumping into the ground to head back to the plant ? . Is the claim that the equipotential plane is subjecting the cows to current flow they wouldn't otherwise be in contact with if there was no equipotential plane ?

David

 

[M. D.]

This is from the same proposal

....What happens is the equipotential plane is such a good, efficient low
impedance contact with the earth that the equipotential plane acts as a ?sink?
for the majority of the stray neutral current flowing through earth in the
vicinity. It becomes a magnet for collecting the stray current. This equipotential
plane is connected to the equipment grounding conductor which is connected
to the neutral service entrance conductor which, is connected to the utility
power company?s transformer which has the secondary neutral connected to the
primary neutral thus completing the connection to the primary electrical circuit
back to the transformer.
What should be done is to connect all conductive metallic surfaces that can
become energized to the grounding system through bonding conductors. No
more, no less just as would be done in a home or industry.
If equipotential planes were such a great idea, why not require the basements
and garage floors to have equipotential planes in case someone walked on the
floor in their bare feet? Now watch some panel think that this is a great idea. A
fool is born every code cycle.
No doubt, someone will make the comment that equipotential planes must do
some good, must have a little advantage or may afford some help. That person​

needs to face the facts ?

THERE IS NO BENEFIT IN ANY WAY, SHAPE​

OR FORM FROM EQUIPOTENTIAL PLANES, ONLY HARM. ​

The​

concept was based on erroneous ideas and conclusions and mis-understanding​

of electrical principles.​

 

[M. D.]

David I did not post it all because it is quite long ,... the other proposal 547.10 is also very interesting. Mr. Zipse has written articles regarding the issue of stray current. A google search on his name should lead to them . He is very aggressive and passionate about this issue.

 

[M. D.]

I think this shows a bit of frustration peeking through.​

19-30 Log #2420 NEC-P19

Final Action: Reject​

(547.10)​

____________________________________________________________

​

Submitter: ​

​

Donald W. Zipse, Zipse Electrical Engineering, Inc.​

Recommendation: ​

Delete the whole Section 547.10.​

Substantiation: ​

For additional substantiation please read 547.2 also.​

How did the misunderstood equipotential planes get into the NEC? In the​

early 1980s it is opined that some agriculture professors read IEEE Standard 80

and being familiar with cow shit and not electrical engineering, misunderstood
IEEE Standard 80. Four Ag professors wrote three papers on equipotential
planes and dairies........​

​

​

 

[M. D.]

here is a link to a newsletter ,.. there is a link at the bottom I have not read the whole paper ,.but it is very interesting and compelling.

http://neccode.com/newsletters.php?action=reply&inResponseTo=3449&letterID=211

 

[dnem]

If equipotential planes were such a great idea, why not require the basements
and garage floors to have equipotential planes in case someone walked on the
floor in their bare feet? Now watch some panel think that this is a great idea. A
fool is born every code cycle.

I love that section of your post !

David

 

[M. D.]

Mr. Zipse said It, I just cut an pasted it. Did you read the paper found via the newsletter??

I like this one ;

Donald W. Zipse, Zipse Electrical Engineering, Inc.​

....1980s it is opined that some agriculture professors read IEEE Standard 80

and being familiar with cow shit and not electrical engineering.....​

 

[wwhitney]

....What happens is the equipotential plane is such a good, efficient low impedance contact with the earth that the equipotential plane acts as a ?sink? for the majority of the stray neutral current flowing through earth in the vicinity. It becomes a magnet for collecting the stray current. This equipotential plane is connected to the equipment grounding conductor . . . thus completing the connection to the primary electrical circuit back to the transformer.

Would inserting an appropriate resistor between the equipotential plane and the EGC system relieve the stray current problem without hurting the "equipotentiality"?

Cheers, Wayne

 

[M. D.]

I think the point is there is no "equipotentiality" and the solution , as far as Mr. Zipse is concerned, is to stop the primary to secondary neutral to ground connection.

EQUIPOTENTIAL PLANES, A FIGMENT OF THE IMAGINATION
Prelude to the Institute of Electrical and Electronic Engineers? (IEEE) paper​

Copyright Material IEEE​

Paper No. ICPS-06
Donald W. Zipse, P.E.
Life Fellow, IEEE​

Electrical Forensics, LLC​

PO Box 7052
Wilmington DE 19803-0052
USA​

don.zip@ieee.org​

Panel 5 needs to recognize the dangers and hazards​

associated with the multigrounded neutral electrical
distribution system and to remove the acceptance of this
electrical distribution system from the NEC.
The above action will reduce the potential for electric
shocks emanating from multigrounded neutral electrical
distribution systems, but will not remove them. Only by the
elimination over a period of years of the multigrounded neutral
electrical distribution system will North America become safe
from stray neutral distribution current and the shock
consequence of uncontrolled flow of stray current over the
earth.​

 

[dnem]

What exactly are the alternatives to multigrounded neutral electrical distribution system ?

I'm thinking of 2

1] Run a fault current only EGC down the street from substation to transformer to transformer. . Right now the utilities try to dump their neutral currents into the ground to return, it would be quite an accomplishment to get them to just run a neutral. . Does anybody think they're going to ever run another conductor in addition to the neutral ? . You might as well forget that option.

2] Get the utilities to install neutrals on every single wye distribution and bond them to an electrode conductor at the source transformer secondary only. . Each source transformer secondary would then have a local electrode that would connect it directly to the earth underneath it.

#2 sounds good but I see one drawback. . With a single point neutral bond at the source / secondary end and not at its destination / primary end, if a primary phase conductor comes in contact with the transformer enclosure, the only path back to the source would be down the electrode conductor into the earth, thru the earth back to the location of the source transformer, and up the electrode conductor to the source transformer. . So would the destination transformer have any effective OCP for a primary conductor fault to the enclosure ?

David

 

[M. D.]

Zipse and co. found that the insertion of a neutral blocker worked pretty well for dairy farmers , however they are not always installed properly .

....the insertion of a neutral blocker (a​

form of a lightning arrester) between the primary neutral and
the secondary neutral reduces the amount of stray current by
40 to 60 percent. Usually, as soon as a neutral blocker is
installed or better yet a transformer that isolates the primary
neutral from the secondary neutral is installed, the milk
production increases and the health of new, fresh cows does
not deteriorate.​

​

 

[dnem]

Would inserting an appropriate resistor between the equipotential plane and the EGC system relieve the stray current problem without hurting the "equipotentiality"?

Cheers, Wayne

A resistor connected to a fault current only conductor will have no voltage drop, therefore potential to earth with remain at zero on both sides of the resistor. . This sounds good theoretically but do we know of any unanticipated consequences that might happen during the fault ?

If hard data exists for this option, then a code change could be proposed and might get serious consideration especially noting that Wisconsin has already taken action against the current setup of the equipotential plane. . The resistor idea could make its appearance in 547 for 2011 and, if successful, expand to 680 [and 682] for 2014 [altho I hope they scrap the equi plane from 682 completely].

David

 

[M. D.]

Would inserting an appropriate resistor between the equipotential plane and the EGC system relieve the stray current problem without hurting the "equipotentiality"?

Cheers, Wayne

I don't think so because stray current will flow through the equi grid regadrless on it's way back to the supply.

 

[wwhitney]

A resistor connected to a fault current only conductor will have no voltage drop, therefore potential to earth with remain at zero on both sides of the resistor. . This sounds good theoretically but do we know of any unanticipated consequences that might happen during the fault ?

If I understand correctly, the equipotential plane isn't designed to clear faults itself, i.e. it is not necessary that a phase conductor shorting to the equipotential plane trip the OCPD.

For a fault elsewhere, the equipotential plane provides a parallel path to the service: instead of EGC to service neutral, we have EGC to equipotential plane to earth to GES to service neutral. Admittedly this is a much higher resistance path; adding a resistor as suggested will only increase the resistance of this undesired secondary path.

Cheers, Wayne

 

[wwhitney]

I don't think so because stray current will flow through the equi grid regardless on it's way back to the supply.

My understanding is that stray current will take all paths back to the source. Then the problem that the equipotential grid creates is that it is a much lower resistance path back to the source, so alot of the stray current takes this path back. Increasing the resistance of the path through the equipotential grid should reduce the stray current through it back to "background" levels. Or do I misunderstand?

Cheers, Wayne

 

[don_resqcapt19]

I don't see how the fact that the equipotential grid is a lower resistance path for the stray current really makes any difference. If you have an equipotential grid, then for all points on the grid, the only voltage potential is that caused by the voltage drop across the grid itself. I would expect that this voltage drop would be very small....well under a volt.
Don