I coauthored an official response to Mr. Zipse's paper entitled "Power Systems Grounding Perspective to 'Equipotential Planes, A Figment of the Imagination'" that was published in the proceedings of the same conference as Mr. Zipse's paper. It seems in the newsletter, the author fully misrepresented the content of the paper as a "regurgitation of the Agriculture Red book, Document 696." It is obvious that the author didn't read the paper. I would encourage those interested to obtain a copy. It discusses Mr. Zipse's opinions in the context of accepted standards and classical engineering concepts.

It seems correct. We dealt with this issue in electroplating with a conductive fluid. The system is not flat. With discrete electrodes, or even a solid electrode at the bottom, the distribution looked as a parachute.

The model is adapted 100+ years old from telegraph pole & wire system grounding calculations.

I would say the best bet would be to isolate the cows from the ground.

The river can do what it will but it won't affect bridge traffic unless it gets too high.

The superiority of multigrounded primary distribution has been proven over time. The multiple grounds reinforce each other to provide superior resistance to lightning. Multiple grounding of the neutral also permits the earth to serve as a backup neutral so that an open neutral will not toast transformers and houses and so forth.

The amount of current that flows into an equipotential plane is limited by soil resistance. Sure, the plane cannot have zero voltage difference between one end and the other, but the idea is to lower the voltage difference to harmless levels. An euipotential grounding grid is better than no defense and has beed shown in actual case studies to be very effective.

Ungrounded secondary systems such as 480 volts ungrounded have more than their fair share of damage from silent and invisible lightning such as Saint Elmo's Fire. Some people have actually bragged to me on job interviews about how many motors they replace each.

I have been shocked twice by picking up a 1.5 volt D cell by the ends. This was because I failed to wash my hands over several hours and allowed perspiration salts to build up. I can see why cows do not like the Cow Voltmeter Method.

I have also seen and felt first hand what happens when a failed 120 volt underground electrical line is leaking 7 amps into the soil DURING A DROUGHT! The stray voltage in this situation ( about 30 to 90 volts ) far exceeds what a multigrounded neutral system normally produces. This current flow partially energizes concrete basement floor and metal drain plumbing causing correctly grounded washing machines and faucets to have a nasty tingle voltage. Since bare feet are relatively insensitive to electric shock people think that the object that they are touching is what is hot, but it is their feet that are hot.

An equipotential grounding grid around and underneath a swimming pool is for the purpose of defending the pool against EXTERNAL threats such as failed underground wiring, downed power lines, and lightning current. Against a 13,200Y23,000 volt ground fault a city block away sure would push the limit of the #8 solid wire that National Electrical Code requires but nevertheless such a ground fault typically can find better grounding electrodes elsewhere to carry most of the current.

A consistent lie in NEC is that a nonmetallic in ground swimming pool does not need an equipotential grounding grid but that can be shown to be false. All insulators, including a theoretically perfect insulator, store charge, what is known as capacitance and therefore has capacitive reactance. Capacitive reactance is the ability to resist but not stop the flow of alternating current. One of my experiences with variable frequency drives is that water increases the capacitance of allegedly waterproof insulation ( THWN ) to the point that the 2,000 Hertz or so carrier shorts out even though the circuit is only about 40 feet long.

I have sworn off swimming pools because the 3 swimming pool contractors I have encountered do not understand why an equipotential grounding grid is needed. The 3 instances are:

1. The pool that I wired in 1988 in inherently unsafe because only the pool deck and metal walls down to about 4 feet are bonded and grounded. The concrete walls below the steel wall as well as the concrete floor have NO reinforcing steel. The pool has a plastic liner but as I pointed out above the liner is a home made capacitor.

Just a few weeks ago I saw a truck for this pool contractor so they are still in business.

2. The next instance was the Mikvah bath over at Revere Road Synagogue in Akron, Ohio which was built around 1999. After I pointed out to Rabbi Sasonkin what was wrong with the installation he made the concrete contractor grind out the concrete and expose a rebar so that the electrician ( someone else ) could bond the rebars to the pump and deck.

As a side note, the Summit County electrical alleged inspectors allow aluminum service entrance cable to supply a subpanel that supplies a pool in a new installation. NEC requires such a new feeder to be in conduit.

3. The Akron General Medical Center neuroscience building has a partially in ground hydrotherapy tub that has nonmetallic walls. There was no equipotential grounding grid around and underneath the walls to intercept an Ohio Edison ground fault from forcing current through the capacitive reactance of the pool wall. Asking how much current would be like asking how much a yellow jacket sting hurts. Ohio Edison has both 2,400Y4,160 volts and 13,200Y23,000 volts running underground in this area plus extensive 120/240 volt 120Y208 volt and 240 volt corner grounded underground lines in this area.

Neither the registered professional engineer not the city plans examiner not the electrical inspector could recognize what an ad hoc capacitor looks like.

To make things worse, the nonmetallic pool manufacturers talked NFPA into repealing the 2005 NEC requirement for an equipotential grounding around the contour of any in ground swimming pool. Nonmetallic in ground pools are again exempt by civil law from needing an equipotential grounding grid but not by the laws of physics and circuit theory.

My only defense against liability then is to swear off in ground swimming pools. None of these so called experts recognizes why an equipotential grounding grid is needed.

Mike Cole mc5w at earthlink dot net Telephone: 216-524-2185 450 Meadowlane Road Seven Hills, Ohio 44131

I forgot to mention that on a well balanced 3 phase 4 wire multigrounded system the neutral current at the substation is a small fraction of the phase current. 50% or even 80% of a small current flowing through the earth is more or less innocuous. If during a peak demand period a feeder is carrying about 400 amps per phase because power has been rerouted, the neutral current may only be 50 amps or even less. I would not be surprised if the total neutral current under noraml conditions is more like 10 or 20 amps at the substation.

Primary voltage capacitors are typically connected phase to neutral which helps to get rid of triplen harmonics from fluorescent lights plus the normal capacitance to ground plus series inductance acts as an ad hoc low pass filter.

Feeders are normally loaded to only 50% capacity both to increase longevity and to reduce "magic square" type problems when power needs to be rerouted.

It is on long and heavily loaded single phase branches that stray primary voltage gets to be a problem. One of the dilemmas in rural and suburban distribution is that the customers who are farthest from the substation are the ones that need all 4 primary wires the most. The customers who are farthest from the substation are the ones who also need for 3 horsepower and larger motors to be 3-phase the most.

A comprise on long rural branches is to run 2 primary hot wires and a neutral. You would then connect single phase transformers phase to phase creating a mixed multigrounded/ungrounded system. These single phase transformers could then supply single phase to 3-phase converters.

Single phase to 3-phase conversion technology has inproved in recent years. Ronk makes a rotary phase converter that uses a tapped autotransformer and a programmable controller to adjust phase conversion to match actual load better. Mirus International also makes a unit that is both a harmonic filter and static phase converter that operates 3-phase input variable frequency drives off of single phase power.

I think it's good to challenge the long held assumptions. If they are good, they'll survive. If not, they'll fall by the wayside.

regarding making a capacitor, to discharge same, you need a conductive path to the stored charge. Often this is not hard to obtain...

regarding the measurements done, both in the article and elsewhere, measurements can be wrong if everything isn't taken into account.

I've seen too many basket case buildings that appear to have been wired by the Dad in "A Christmas Story." Farms have the problem of asset-rich, cash-poor business. They can't afford professional service so they do it themselves.

It will be interesting to see how this plays out.

I was disappointed in this. I downloaded the paper and looked it over. It may explain the problem, or it may not. It was too encumbered with blather. I got tired of wading through the BS and dumped it. I would like to see a cogent explantion of the problem and possible solutions, but it isn't here.

We have discussed this very issue several times on the Forum.

The current requirements in the NEC actually places normal operating current on the grounding system and exposed non-current carrying metal parts.

The NEC seems to be obsessed with producing the lowest resistance to earth possible on the electrode system. At the same time, the NEC permits the reduction of the grounded (neutral) conductor which is responsible for return of all normal operating current back to the source.

With the NEC mandated "super-low" grounding electrode earth resistance and NEC permitted higher impedance neutral return path. Simple OHMS LAW clearly shows that as the resistance of the neutral path increases, while at the same time the grounding path resistance decreases, more current will flow back on the grounding electrode system.

Throw a pool into the mix, and it and it metal components effectively become a grounding electrode. If excessive current is flowing over the grounding electrode system, that same current can and will also be seen on the pool structures.

So even if the galvanic action can be suppressed by proper bonding, and even if the utility stray currents are reduced or eliminated, the current grounding requirements of the NEC will still produce potential lethal currents on a pool's equipotential grid.

It would make the argument easier to understand if you separate 60 cycle current from everything else. Do I understand the the point being made? I am not sure, but it seems there is a claim that a very large percentage of return current flows though soil back to it's source. Ok, the source is different if we are discussing a home powered by a pole mounted transformer, or a distributions substation powered by a generator miles away. Also, you must keep in mind that soil resistivity is not homogenous, in fact, nothing could be further from the truth. Soil resistance is different both at depths as well as distances at the same depth. It all depends on the contact resistance of many particles, all working together like a matrix of resistors. Get across this matrix of resistors at two given point, and you will measure a voltage. The voltage will be the produ ct of whatever current is flowing and the resistance of the circuit created by the two contact points. If anyone is interested, I have a simple device one can use similar to a metal detector, but it is designed to measure ac voltage as low as 1 volt in soil or in concrete, street, roads, etc. The device is immune to surrounding voltages, and only measures voltage in one direction. If anyone is interested in this device, contact me at the address above.

The paper discusses the stray current from the substation. NOT the local transformer. All multiple conncetion of the secondary side of the local transformer are fixed so that there is only one connection to the earth on the secondary side and /or the secondary side is 480 volts ungrounded delta.

The proble is not the secondary side of the local transformer, but the distribution circuit.