Mike:

Stray voltage, even according to all your information, has to do with ground and neutral currents relative to DISTRIBUTION lines or premises wiring. So why does your email article on stray voltage include a picture of a 765-kV TRANSMISSION line. Heck, a transmission line doesn't even have a neutral!

I wouldn't expect this kind of sensationalism from you!

That is precisely the point - HV distribution relying on the ground as the neutral is the major contributor to stray voltage!

Mike, are two separate problems. The first is that as I have repeatedly said in these forums: The neutral is not at ground potential unless your point of reference of the neutral is earth grounded without interfering impedance. No great mystery, just common sense and an inkling of electrical knowledge. Now, the farmer may have a neutral to ground current problem but he may also be having an induced current problem-a whole different animal. Powerful alternating magnetic fields can under certain circumstances induce high voltage current in objects along their transmission path.

just a little story of my experiance with stray voltage. i worked on a dairy farm for years and every time i put my hands in the water to was the milkhouse i got a small shock. i told the owner he didnt beleive me cause he always had rubber boots on. i grabbed the multi meter and sure enough 10 volts in the water. so he called the local electric comp. and it ended up being the cable company used the ground so it was traveling into the barn. problem fixed milk production raised 9 percent the next day.

It's about time Being a farmer with an electrical background bonding is the key. It takes a little extra time and material to protect the heard but it's worth it.

Hi Mike—I reviewed your video presentation on stray voltage (NEV) and am highly curious about a few of your comments and would like to bring a few points to your attention. 1. Mastitis is an infection of the mammary gland of the dairy animal (actually humans as well). Mastitis is caused by more than one factor; however, it is normally associated with a pathogen that is not cleared in a normal fashion by the immune system and the white blood cells or somatic cells which cause a rise in the somatic cell count (SCC) of the dairy cow. Incomplete milk out, trauma, inflammation and numerous other circumstances can exacerbate the pathogenic affect. A dairy animal with an immune system that is not compromised by stress can normally clear the infection, however a stressed dairy animal does not clear the infection as well which in turn causes a downward spiral that the dairy animal may not have the ability to overcome. In this situation the use of intermammary infusions (IMMI) may help the dairy animal clear the pathogen (the use of IMMI and other therapies are used according to the prescriptions written and authorized by the consulting veterinarian providing the health care to the dairy operation}. If this does not clear the infection even stronger therapy may be required and only with the knowledge of the consulting veterinarian. If this does not clear the infection, death or severe health complications may result. In severe cases this may lead to death in hours not days! As you stated so very accurately being shocked when being milked leads to abnormal behavior and if it is severe enough the person can get the “H” kicked out of him or her. This abrupt movement may cause pathogens to be “injected” into the mammary gland due to high velocity teat end impacts due to the negative pressure used in the milking process. When the cow moves it can cause liner slips or noises which allows air flow directly into the streak canal, into the milk cistern and mammary glands of the dairy animal which in turn causes mastitis. (We didn’t have this problem with milking by hand). 2. Anything that upsets the normal daily routine of the dairy animal such as shocking when walking, resting, eating or drinking may cause additional stress and should be avoided to the extent possible. This type of stress may lead to displaced stomach (the dairy animal has 4) which may very likely require surgery to correct (insert very costly) and you can have complications from the surgery as well which may be exacerbated if the dairy animal does not eat or drink as well as they should. The above are only a couple of the complications that may be associated with undue stress from stray voltage in the dairy animal’s environment. You have made excellent points in your presentation on the electrical distribution serving dairy farms and most parts of the US. However, you seem to be leaving out some crucial points in your presentation and PLEASE correct me if I am incorrect. Your schematic shows a delta feed (I assume Transmission) into a grounded wye distribution without having down grounds at a minimum of 4 down grounds and ground rods per mile, as well as the grounding required by the NESC in addition to the 4 per mile on a multi-grounded neutral wye distribution. Your presentation actually more closely represents a uni-grounded wye system with the primary neutral bonded to the secondary neutral on the dairy farm (utility) transformer. You have stated the following in the intro to your newsletter: “The term stray voltage has been used for the past 40 years to describe a special case of voltage developed on the grounded neutral system of a farm. If this voltage reaches sufficient levels, animals coming into contact with grounded devices may receive a mild electrical shock that can cause a behavioral response. At voltage levels that are just perceptible to the animal, behaviors indicative of perception such as flinches may result with little change in normal routines. At higher levels avoidance behaviors may result.” If you are intending this to reflect only, “developed on the grounded neutral system of a farm” and want to exclude earth currents associated with the grounding of the “electrical distribution to the dairy farm”, then your presentation reflects a more accurate description; if however, that was not your intent then you need to address the grounding and bonding associated with the NESC for multi-grounded neutral wye distributions and the creation of stray currents and potentials associated with multi-grounded neutral wye distributions systems. A publication of the National Rural Electric Cooperative Association (NREAC) makes a number of clear statements that I agree with, see if you agree. 1. “Stray Voltage Fundamentals and Sources” In a multi-grounded distribution system, there will always be stray voltages and currents. At the customer’s facility, these voltages result from the interaction of multiple parameters of the primary and secondary systems. Some of the most influential parameters include unbalanced loads, neutral wire sizes and lengths, and grounding electrode systems. Basically, the magnitude of N-E voltage depends on the current flowing in the grounded neutral paths and their impedance. This N-E voltage ultimately determines the current flow and resulting earth gradients in the customer’s facility.” 2. Ground Rod Purpose “Grounding Electrode System 60 Hz Resistance of Grounding Electrode System. Low-resistance grounds are necessary to ensure the proper operation of equipment during abnormal circumstances, such as lightning strokes and phase-to-ground faults, as well as to meet appropriate codes and standards.”

3. NEC (The NEC Section numbers may have changed but I will quote them as stated.) “Article 547 Agricultural Buildings, Section 547.9 Electrical Supply to Building or Structures from a Distribution Point and Section 547.10 Equipotential Planes and Bonding of Equipotential Planes. With the intent of reducing the N-E (neutral to earth) voltages, Section 547.9 (B) (1) allows isolation between the neutral bus and the ground bus in the distribution panel serving agricultural buildings. However, the following constraints are listed: • The equipment-grounding conductor shall be the same size as the largest supply conductor, if of the same material, or shall be adjusted in size in accordance with the equivalent size columns of Table 250.122 if of different materials. • The equipment-grounding conductor shall be bonded to the grounded circuit conductor at the disconnecting means enclosure at the distribution point or at the source of a separately derived system. • A grounding electrode system shall be provided in accordance with Part III of Article 250 and connected to the equipment-grounding conductor at the building(s) or structure(s) disconnecting means. • The grounded circuit conductor shall not be connected to a grounding electrode or to any equipment-grounding conductor on the load side of the distribution point.”

To this dairy farmer, the above describes a 4 wire single phase secondary distribution on a dairy farm or a 5 wire 3 phase secondary distribution for a dairy farm. It is my understanding that the NEC has changed the code to require this configuration in new installations on dairy farms and with what I believe to be excellent reasoning, see if you agree with my reasoning. By installing a separate conductor for the neutral (grounded conductor) and the ground wire (grounding conductor) you have eliminated secondary neutral voltage drop as a contributor for NEV on the dairy farm because the neutral conductor is forced to carry the neutral current back to the X2 or X0 of the transformer and the grounding conductor is then dedicated to function as a “safety wire”. Monitoring can be installed to alert a dairy farmer to the presence of an elevated voltage or current on the grounding conductor and the dairy farmer can then take the appropriate measures to correct the situation before situation is severe enough to cause a behavioral response by the dairy animal. In the above configuration, the secondary farm distribution would not have any contribution to a stray voltage condition unless the dairy farm is not isolated from the primary distribution which is specifically allowed in the NESC. If the isolation provides highly effective isolation from the primary neutral and associated earth currents, why would you want to inject electricity (insert energize) directly into every single space a cow may have the unfortunate displeasure to be confined to? To this simple dairy farmer, this is simply absurd!! In reality what we are discussing is the utility using the dairy farm grounding to act as a conductor to allow primary neutral current to access earth in its (insert earth currents) path back to the source (insert substation in this situation). There are far better options available to prevent the primary neutral current from accessing the dairy cow’s environment and you have mentioned a transformation from one type of distribution to a different type of distribution and its advantage to preventing NEV that too is addressed in the NRECA document, as follow in part under system grounding methods. “Solidly Multi-Grounded or Four Wire Grounded Neutral System“ ¬¬¬“Disadvantage – Results in a neutral to earth (N-E) voltage, which can contribute to stray voltage.”

“Ungrounded Systems” “Advantage - It does not contribute to stray voltage”.

“Solidly Unigrounded Systems” “Advantage – It does not contribute to stray voltage.”

“Resistively or Reactively Grounded System” “Advantage – It does not contribute to stray voltage”

“Resonant Grounded System” “Advantage – It does not contribute to stray voltage.”

Bottom Line: “In a multi-grounded distribution system, there will always be stray voltages and currents.” However, they do not have to get to the dairy animal, her environment and dairy farmers should not have to spend additional dollars to try to alleviate a utility problem. Spend your dollars for highly effective isolation and do not take one of the most hazardous properties –electricity -- and spread it out all over everywhere—confine it to the electrical conductor and complete the circuit back to the source, on the wire. This will resolve the NEV and maintain the integrity of a simple electrical circuit which is simply out to the load and back on the intentionally designed electrical conductor. This eliminates normal NEV on the dairy farm. Chuck Untiedt –just a dairy farmer