EMF ??


22 October 1999
18 February 2000

---------- Forwarded message ----------
Date: Sun, 13 Feb 2000 05:51:13 -0600 (CST)
From: "Roy L. Beavers" <rbeavers@llion.org>
To: emfguru <rbeavers@llion.org>
Subject: Re: Comment on "Stray voltage story (Beal)
(Kingsbury)(Lundquist).. (Dahlberg)..

.......Dr. Dahlberg has written a good summary comment to the "stray voltage" discussion of the past week, which included speculation about harmonics and transients causing the observed effects?.....  Particularly notice Dr. Dahlberg's mention of the "common occurrence" of a noticeable impact upon the immune system.....  (I am also adding this as an intro to the Stray Currents paper that is already posted on the website....)

Those who contend that "there is not an EMF health effect" are simply choosing to ignore the many examples of electric exposure effects on dumb animals in barnyards that have been documented around the world.  Those creatures cannot be accused of any "its all in your mind" psychosis.....

Cheerio......  (Many thanks, Duane....)

Roy Beavers (EMFguru)

It is better to light a single candle than to curse the darkness

People are more important than profits!!

---------- Forwarded message ----------
Date: Sat, 12 Feb 2000 18:28:54 -0600
From: "Duane A. Dahlberg" <dahlberg@cord.edu>
To: "Roy L. Beavers" <rbeavers@llion.org>
Subject: Re: Comment on "Stray voltage story (Beal)

Dear Roy

Regarding harmonics--radio frequencies and stray voltage on dairy farms:

Effects from electromagnetic (EM) energies are very difficult if not impossible to specifically nail down.  There are many issues:  Are the noted effects caused by electric currents, electric fields, or magnetic fields?  Are the effects related to frequency or independent of frequency? Are the effects from EM energies only biological, or do they also cause health problems?  These questions highlight the fact that it would be difficult for any one of us individually to have enough insight and information to reach our arms around this problem.

Stray voltage is but one of the subsets of the overall issue of EM exposure and possible effects.  Stray voltage does not involve a different entity, but mainly relates to how EM energy impacts the bodies of humans and animals.  The bottom line is that "stray" currents are in the materials with which humans and animals make contact.  That contact point is primarily the earth or floor of a building.  Of course there are also electric and magnetic fields, but the factor that best correlates with the effects on a dairy farm is the electric current that is free to enter the bodies of humans and animals through their contact with the floor of the barn.  Obviously if these currents are present in the floors of barns, they are also present in homes, schools, shopping malls, etc.

Throughout the 60-year recognition of stray voltage, the one predominant thread is electric current advertently or inadvertently entering the earth. During the past 20 years, numerous case studies have supported the association between electric current entering the earth and behavioral, health, and production problems of livestock. Although the currents entering the earth are mainly 60 Hz, the nonlinearity of the earth can distort the 60 Hz so that it becomes a very complex waveform.  This waveform can be represented by the harmonics of the 60 Hz frequency.  In addition, there are transients coming from different sources that can also distort the 60 Hz wave form.  Because of the large quantity of electric current that is shunted through the earth and the electrical nonlinearities of materials in the earth, the reservoir of EM energy in the earth is a complex and ever-changing array of frequencies and magnitudes.  One might conclude, therefore, that harmonics or transients are causing the stray voltage effects.  In some cases there are correlations that support this conclusion.

When considering radio frequency (RF) currents, it is important to keep in mind that these currents travel at the surface of the earth and on the outside surface of distribution and transmission lines.  What role these energies play in the health effects associated with stray voltage is difficult to assess.  Research from Eastern Europe has described a set of perceived effects from exposure to radio waves and microwaves that is quite similar to the human health effects experienced by dairy operators.  Based on this information, one could conclude that the perceived effects in the dairy barn are caused by the RF carried on the distribution lines and at the surface of the earth.

There is merit to both the RF explanation and to the harmonics and transients approach, but there may be other scenarios that have equally sound justification.  Exposures to differing EM energies can cause similar health problems.

In my investigations of the stray voltage problem I have found that electric conditions vary from one stray voltage dairy farm to the next. The level of RF in the ground and/or floor of the barn is quite variable. On some farms the levels are very low, whereas on other farms the levels are higher.  In general the electric field levels of the RF are much less than those of 60 Hz.  A number of the stray voltage farms on which I have made measurements and collected health and production data are near DC transmission lines.  On these farms one finds human health effects that are very similar to those caused by RF as presented in the Eastern European work.  Both the perceived effects in humans and the stray voltage effects in the dairy cows correlate with the activation of the DC line.  I would at least suspect that DC fields and/or perhaps the ions produced in the region of these lines played a role in the effects.

There is a body of information in the research literature detailing the chronic effects of electrocution.  Whether electrocution is caused by a high voltage 60 Hz source or a lightning strike, the chronic effects are similar to those occurring from RF and microwave exposure.

When I question electrically sensitive people, I find that they are affected by all forms of electrical energy.  There seems to be no type of electrical energy that stands out as a dominant cause for their perceived effects.

Many of those involved in the investigation of stray voltage have found that exposure to electrical energy appears to cause a stress on the cows that is connected to a progressive destruction of the immune system.  This finding is common on all dairy farms that have been treated as stray voltage cases.  There are also other effects that go beyond the breakdown of the immune system.  One of these effects is death by electrocution. There are documented cases of healthy cows dropping dead in the barn, and of healthy cows dying when lying at specific locations in the barn.

Since I am a systems person, my perception is that the body functions as a system.  As a system, health effects can be initiated either by something that interacts with the system as a whole, or by something that attacks a specific part or function of the system.  I think EM energy is capable of both.  When health effects are caused by a system interaction, the frequency of the EM energy may be a minor factor.  The major factor is likely to be exposure to a level of external EM energies that is capable of affecting the electric system of the body. This appears to be the best explanation for the fundamental health problems on stray voltage dairy farms. The kinds of stress observed in dairy cows affected by stray voltage suggest that electricity is negatively interacting with the entire electrical system of the animal.


Duane A.Dahlberg, Ph.D.
The Electromagnetics Research Foundation, Inc.
1317 6th Ave. N.
Moorhead, MN 56560-2118


Duane A. Dahlberg, Ph.D.


There is a problem in the dairy industry which has defied solution.  While it is most often associated with the dairy industry, it can also be found elsewhere.  Industry, dairy operators, and agricultural schools of universities have all struggled with the problem, searching for solutions.  Diverse models have been proposed to explain the cause or causes, and various mitigation procedures have been implemented to assist the dairy operators in managing their herds.   This specific problem is called stray voltage.

Stray voltage is perceived differently by the affected dairy operators and those investigating the problem.  Fundamentally, the term stray voltage is applied to a problem associated with electricity that affects the behavior, health and production of dairy cows.  As the problem has been studied more extensively, stray voltage has also been associated with effects on other animals and people.  For a period of over 50 years the dairy industry has been aware of the need to maintain a trouble free electrical system in the environment of the dairy farms.  Dairy cows are known to experience a set of behavioral, health and production effects when an electrical problem exists proximate to dairy farms where electricity is short-circuited into the earth.  Dairy operators perceive these effects to be a general attack on the well being of the cows.


Nearly all of the research related to stray voltage has been carried out at university dairy barns.  These efforts have focused primarily on how electricity might affect dairy cows, and the research has assumed that the cause of the problem is electrical shock.  A shock in the dairy barn is defined as a pulse of excessive electric current passing through the cow while the cow is standing on the concrete floor and touching another conducting  part of the barn.  The assumption has been made that the floor of the barn is a true ground connection.  The other conducting parts of the barn with which the cows can make contact are connected to the farm and the electric utility neutrals through the electrical grounding system.  Currents in the earth produce a potential difference between these points.  If that potential is sufficiently high, a pulse of current is momentarily present in the cow, causing the animal to pull away from the contact point and to demonstrate visible behavioral responses.  A physical response from the cow, such as a sound or a sudden movement of some part of the body, is considered as evidence that the electricity is affecting the cow.  It is further assumed that health and production effects will occur only if the electric potential is sufficiently high to produce an observable behavioral response  This approach is called the shock model for stray voltage effects.

Research based on the shock model assumes that cows in the research facility are not being affected by stray voltage if they are in a barn free of shock potentials.  Any other electromagnetic (EM) energies in the cows environment are, therefore, neither known nor monitored.  These assumptions lead to the preparation of a research environment in which the electric currents that can access the cows cannot produce a perceived shock.  In response to these research assumptions, the research dairy barns are built or renovated so that the electrical potential levels are within the range considered safe for the cows.  The most common adaptations of  the dairy barns are adding an equipotential plane, installing three phase electricity,  electrically connecting all conducting parts of the barn together, and sometimes electrically isolating the secondary and primary neutrals.  These alterations do not eliminate the cows exposure to EM energies; they only limit the possibility that the animals can be shocked as they touch two points at different electrical potentials.  EM energies include any energy associated with magnetic fields, electric fields, electric currents and microwave and radio frequencies.

Stray voltage research has primarily focused on the shock model, and in general it has been conducted in university dairy barns which are assumed to be shock free.  The research has been designed to test the possibility that electrical shock may affect the behavior, health, and production of dairy cows.  The experimental animals are exposed to intermittent 60 Hz electric potential  for periods of weeks and sometimes months.  Control animals are selected from among the other dairy animals in the university barn.  The number of cows in the experimental group is frequently less than 15.  Cows for the experiments are chosen very carefully.  Often cows late in the lactation cycle are used; the cows must have a record of being free of infections and diseases, and they must have all of the necessary vaccinations.  Because of the concern for the physical welfare of those handling the cows, cows that react too violently to electrical shock may be removed from the experimental group.

The results and conclusions of shock effect research up to about 1991 were published by the U. S. Department of Agriculture (Lefcourt 1991).  The general conclusions are that "Some moderate behavioral changes are seen in cows exposed to currents of between 3 and 6 mA.  If exposure to such currents occurs on-farm, the behavioral changes may require an additional investment of time from the dairy operator" (Lefcourt  7-1).  "Direct economic effects including reductions in milk yield have been shown for a small percentage of cows (7 percent) at cow contact voltages of 4.0 V and above" (Lefcourt 7-2).  In addition it is stated that, "Experiments involving long term (full lactation) exposures of cows have shown that cows  quickly become acclimated both physiologically and behaviorally to constant and intermittent currents below 6 mA" (Lefcourt 7-2).  These research results precipitated the assumption and the conclusion that any health and production problems are the result of the dairy operator's management of the behavioral problems.  No research is cited, however, that tests this conclusion.  Since 1991 research has expanded to include exposure to transients and 60 Hz magnetic fields.  The primary gauge for determining effects has continued to be the cows demonstration of an observable physical response.  Direct health and production effects have been shown to be caused only by transients, and at levels normally not present at points where cows can make contact.

The research summarized previously does not take into account all of the EM energies to which the cows are exposed.  Even if the assumption is correct that the research barns are free of electric shock, electric currents as well as electric and magnetic fields are always present in these barns, and the dairy cows are continually exposed to these currents and fields.  Most of the stray voltage research, therefore, is a comparison between the behavior, health and production of dairy cows in two different EM environments.  The experimental group is exposed to an additional electrical source.  As a consequence, the experimental results only provide information concerning the difference in effects between the ambient EM conditions and the same conditions plus the added electric current characterized as a shock.  The conditions in the assumed shock-free barn may still be producing stray voltage effects.  Assessing whether or not stray voltage is actually producing effects is complicated by the fact that many of the effects can have other causes, and synergism among causes can also exist.  The availability of a shock current varies from one point to another in the barn, and living organisms of the same species can have individual differences in their reaction to effects from any physical parameter.  With all of these conditions potentially capable of affecting the research results, large numbers of animals would be required to show any clear correlations between the cows experiencing the additional EM exposure and the control group.  Conclusions are limited, therefore, to potential effects from the added shock current for a select group of cows that may not be especially sensitive to shock, and are the healthiest among the dairy cows.

If the shock model provided an adequate explanation for stray voltage effects, then the extent of the behavior, health and production problems should show a relationship to the type of barn in which the animals are housed.  The physical characteristics associated with barn determine the availability of conducting parts which the cows can touch to experience a shock.  In the dairy industry, barns vary from all-wooden construction to a modern parlor system constructed of steel and concrete.  The possibility of the cows receiving a shock is different for each barn type.  If the shock were an appropriate model, a clear difference in stray voltage effects should be evident for the different barn types.  Neither the severity nor the type of stray voltage effects, however, correlates with barn type.

Without research information that assesses possible effects from EM energies other than shock, cows in an assumed shock free research barn may continue to experience stray voltage effects.  When one considers the strong possibility that the additional shock or other EM energy supplied to the experimental group is not the only EM cause of the stray voltage effects, stray voltage research at this time must be viewed as incomplete and cannot be expected to provide a clear picture of the effects of stray voltage in the dairy barns.  Possible effects from exposure to low level and long term electric currents are yet to be studied, as well as long term exposure to electric and magnetic fields.

Specialization, ease of analysis and simplicity in understanding tend to encourage the search for a single cause correlating with a specific health effect.  Consequently studies are undertaken which search for possible correlations between a decrease in milk production of dairy cows, for example, and intermittently exposing cows to an electric shock.  At times solutions are developed which appear to ameliorate the unwanted effects but may not actually address their real cause.  The following two examples are relevant.

An increase in calf illnesses resulting in a poor survival rate is a serious and reoccurring problem for many dairy operators.  There can be many causes for these conditions.  Since calves are housed in the barn in proximity to the cows, one possible cause is the air quality in the barn.  One mitigation procedure for improving air quality is to place the calves in hutches outside the barn.  For many dairy operators this procedure improves the survival rate and the health of the calves.  For others the survival rate in the hutches is still poor; improving air quality for the calves by housing them in hutches has not resolved the health problems.  In some dairy barns, including some university dairy barns, the calves in the barns are observed to have a higher survival rate and are healthier if they are raised up on straw or manure packs.  It is interesting that on stray voltage farms where the behavior, health and production of the dairy cows are adversely affected, often calves also have significant health problems and a poor survival rate.  Consequently, air quality may be only one of the factors affecting the survival rate of the calves.  Since the health problems for the calves continue even with improved air quality conditions, and since exposure to electricity and other factors can affect the calves, additional research is necessary to resolve the inconsistencies.

As the incidence of mastitis and the somatic cell count have increased in dairy herds, measures have been developed to mitigate the problem.  Mastitis is an infection of the udder associated with a number of pathogens.  Somatic cell count is monitored as an indicator of the health of the cow's udder and is frequently associated with incidence of mastitis.  Mastitis is mitigated both with various antibiotics and also with a number of management procedures intended to decrease the spread of pathogens to the individual cow and from cow to cow.  These procedures are beneficial in some dairy herds.  For other dairy herds controlling the spread of pathogens has no long-term beneficial impact on the dairy herd.  In addition, in some dairy barns all antibiotics for treating mastitis are ineffective.  When antibiotics are ineffective, dairy operators and some veterinarians are forced to try other procedures, such as reducing the protein fed to the cows with mastitis.  Another procedure is electrically isolating cows from the earth by housing them in a trailer.  In this complex world, the adverse activity of pathogens may be correlated not only with the presence and the movement of pathogens, but also with symbiotic conditions within the cow and the effect of other external stressors.  The underlying cause of the increasing incidence of mastitis may go beyond the presence and the movement of the pathogens.  As noted in the issues related to calf survival,  the inconsistencies in the results among dairy barns certainly suggest a need for additional studies to determine causes for the increases in mastitis.


The general procedure for investigating a perceived stray voltage problem is to check first on the farm for electrical problems that could cause electric current to reach the dairy cows while in the barn.  If no problems are discovered on the, farm the search is continued for sources of electricity that could reach the cows from off the farm  Throughout the investigation electrical changes are recommended for reducing the exposure of the cows to electric currents.  The mitigations recommended are primarily intended to reduce the possibility of the cows receiving a shock when touching a conducting part of the barn.

The study of stray voltage mitigation provides additional, vital information for assessing the stray voltage problem and its causes.  A variety of mitigation concepts have been used on dairy farms.  Among the most common of these are isolation, the equipotential plane, and the electronic grounding system.  Some results of these mitigation methods, as compiled by The Electromagnetics Research Foundation (TERF), are described and discussed in the following paragraphs.  (Dahlberg and Falk 1995)


The most common choice for mitigating stray voltage is isolation.  Isolation is the separation of the electric utility neutral from the farm neutral so that electric current from the utility neutral is unable to directly enter the farm electrical system.  The electric utility decides whether there is a need for isolation on the basis of the magnitude of the cow contact voltages which originate from the primary neutral.  Cow contact voltage is the electrical potential measured between the floor of the barn and some metal component of the barn with which the cow makes contact.  Individual utilities vary in the magnitude of the cow contact voltage used to determine the need for isolation.  Many have selected 0.5 VAC as the cutoff voltage.  If cow contact voltages are less than 0.5 VAC, the dairy operator is informed that there is no stray voltage problem on the farm.  Isolation is arbitrarily based on a measurement and not on the perception by the dairy operator, nor on the behavior, health, and production problems of the dairy herd.

In a study of 126 dairy farms with isolation devices, four farms had an increase in problems after isolation, 82 farms had either no overall change or a temporary improvement in the magnitude of the problem after isolation, and 40 had a small to significant improvement after isolation.  In general, research has shown that approximately 30% of the isolated farms experience a continued improvement in behavior and milk production.  For some of those farms there is also an improvement in the health of the cows and the people working in the dairy barn.  On the other 70% there is either no improvement or a short term improvement that lasts less than a year.  In studying the individual cases it becomes clear that more than one electrical factor was involved.  For farms near natural gas and oil pipelines, direct current (DC) transmission lines and sometimes alternating current (AC) transmission lines, the isolation devices were less likely to be effective.  If the farm was relatively isolated from other users or sources of electricity, the isolator was more likely to be effective.  Unfortunately even these observations are not conclusive, and exceptions occur.  The presence of open neutral underground distribution lines further complicate the picture.  Frequently problems are more difficult to control in regions where these lines are installed.


The equipotential plane is a metal grid, within and near the surface of the concrete floor, that is electrically connected to all other conductors in the barn.  With the floor and other conductors in the barn at approximately the same electrical potential, the possibility of a significant cow contact voltage is very small.  Of eleven farms that were identified to be using equipotential planes , three became worse, seven had no change, and one had an improvement that could have been the result of a number of other changes  made at the same time as the addition of the equipotential plane.  In nearly every case a short-term improvement was experienced, but this condition did not persist.  In order to continue milking cows on the equipotential plane, dairy operators discovered that it was necessary to disconnect all contacts between the equipotential plane and the primary or secondary neutrals.


The electronic grounding system (EGS) is a device designed to neutralize the cow contact voltages in the barn by introducing electricity into a grounding grid.  Of the 20 farms identified as having or having had the EGS, three had an increase in problems requiring the removal of the system, nine had either a temporary improvement or no change in the magnitude of the problem, and eight farms had small or a significant decrease in the problems.


The experiences of dairy operators and other field investigators differ from the results of the research associated with electrical shock.  Such differences support a need to consider additional research using different models.  Background information directed toward determining the appropriate research is provided in the following section.  The information is divided into three categories:  information derived from the perceptions of dairy operators and other investigators; experimental procedures on dairy farms; and additional models for describing the means by which EM energies can cause effects in the dairy barn.


Dahlberg and Falk (1995) developed a questionnaire for gathering information about stray voltage on dairy farms, and to provide a basis for correlating various aspects of stray voltage.  The questionnaire was distributed among over 500 dairy farms.  Information from one or two farms, or even a dozen farms, would be considered case studies and could not be generalized to the entire dairy industry, nor would they provide a general understanding of stray voltage.  Surveys from well over 500 dairy farms, on the other hand, most of which are affected by stray voltage, can provide a significant quantity of statistical data and information.  A summary of this information has been published (Dahlberg and Falk 1995).  These questionnaires provide an additional level of information which extends beyond case studies and permits some statistical correlations to be developed.  On-farm investigations of the dairy operations can serve as a means of checking the questionnaire data.  First ¼ hand analyses of numerous dairy operations in many parts of the country have greatly assisted in the understanding and the interpretation of the statistical data.  Investigations of dairy farms have provided both specific and general information.

Observations of the actions and responses of cows in the dairy barns reveal that cows sense some adverse stimulus seeming to be continually present in the barn.  Frequently the cows also respond to a random event that appears to be present for only a relatively short period of time and then disappears.  These effects are observed in stalls where the only cow contacts are the hooves of the cows as the cows stand on the floor of the barn.  Noted especially is the appearance of effects from a continuous exposure which can impact the animal chronically.  Usually the effects include a sudden onset of a number of bacterial diseases as well as a gradual deterioration of the muscle and skeletal structure of the body.  In severe cases cows suddenly fall to the floor of the barn, and some of them die immediately.  The overall well-being of the animals tends to degenerate in direct relationship to time spent in the barn.  Housing the cows in elevated facilities which are electrically isolated from the earth significantly improves both the production and health of the dairy animals.

The cows in a stray voltage dairy barn appear to be under stress.  Medical records and veterinarian reports indicate what appears to be a failing immune system of cows in these barns.  Under acute conditions the cattle succumb to an apparent heart attack, in some cases attributed to electrocution.  In general, treatment centers on ameliorating the symptoms in order to restore the health of the animal.  However, treating the symptoms and not the cause has only short-term benefits, and sometimes the treatment is never able to eliminate the symptoms.  Some health problems are diagnosed as being caused by viruses for which vaccines are recommended, but on stray voltage dairy farms the vaccines may fail to restore the dairy herd to its former healthy state.  Another common effect is leg sores.  The cause is normally attributed to a bacterial infection and has a standard treatment.  On some stray voltage farms, however, veterinarians treating the sores are unable to find any treatment which will cause the sores to heal.

Health and production effects occur in all types of barns, whether small or large and whether constructed of masonry material, wood or steel.  The effects are also independent of the manner of housing and milking the cows.  Stray voltage problems occur for tie stalls, stanchions, and parlors.  Neither the type of milking system nor a specific brand of milker can prevent stray voltage problems.  Using milking buckets does not prevent the problem.  Upgrading from buckets to a milk line commonly increases the severity of the stray voltage problem.  Concrete barn floors are one consistent factor in all the stray voltage situations.  Although spending more time away from the barn and the concrete floor improves the health and production of the dairy cows, it does not eliminate the problems.

Upon entering a barn where stray voltage is a suspected cause of problems, the cows hesitate and place their noses at the floor surface.  That action appears to be the determining factor as to whether or not the cows enter the barn.  The same action is noted as a cow approaches the assigned stall.  The actions of the cows while standing in the stalls are indicative of an animal that not only would like to leave the stall but would also like to step off the floor.  They are uneasy, and are seen to "dance" in the stall.  Location in the barn is also associated with the degree of behavioral, health, and productions problems.  In general, end stalls are worse, as are occupied stalls next to or between empty stalls.  Other stalls may be uncomfortable without fitting into any clear pattern.

In a barn where stray voltage problems exist, proximity to any equipment using electrical power increases the problems.  It is interesting to note that in barns where stray voltage problems do not exist,  proximity to a piece of electrical equipment does not in itself cause problems.  Individual differences among the dairy cows is an important factor in the observed magnitude of stray voltage problems.  A significant factor is the greater impact of stray voltage on heifers when initially brought into the barn after freshening.  If the heifers survive the first lactation without any serious heath effects, the potential for surviving as a productive dairy animal is much greater.

Measuring EM energy exposure in the cow environment is important in assessing the manner by which electricity can cause effects.  Efforts to establish an acceptable measurement protocol has been a continuing process.  The traditional protocol concentrates on three measurements:  The AC voltage between the utility neutral and a remote ground rod (called the primary NEV); the AC voltage between the farm neutral and the same remote ground rod ( called the secondary NEV); and the AC voltage between the floor of the barn in a stall and some conducting part of the barn to which the cow can make contact (called the cow contact voltage).  These three measurements are a convenient protocol because they are easily measured and can be standardized for all types of dairy operations.  In this protocol the only measurement which has any relevance to the cows environment is the cow contact voltage, experienced by the cow only when the cow touches a conducting part of the barn.  A more complete protocol would include information concerning all electric currents accessing the cows, both AC and DC voltages, as well as measurements of electric and magnetic fields in the cows environment.  Measurements of short-duration voltages, fields and currents are also important.

One electrical property that correlates with the probability of behavior, health and production problems is the conductivity of the earth and/or the concrete floor.  When a concrete floor is new, its water content is higher and therefore its conductivity is higher.  In construction of new buildings, carpenters are warned to not work on "green" concrete.  A similar higher conductivity exists in the concrete of the new dairy barn.  In the dairy industry, there is a phenomenon known as the "new barn syndrome."  For some period of time after the construction of a new barn, the dairy cows experience more problems in the barn.  Dairy farms in areas of high earth conductivity, often coincident with a greater water content of the soil, have a greater potential for problems.

One electrical characteristic of the cows environment has most frequently correlated with both the magnitude of the stray voltage problem in a specific barn and the locations in the barn of the most severe problems.  In some barns there are measurable currents in stall dividers and in other conducting parts of the barn, although they have no intentional connection to the electrical system on the farm.  They are, however, all connected in some way to the earth.  The AC currents can vary from a fraction of a mA to 100 mA.  Changes in electrical use, both on and off the farm, correlate with changes in the currents in these conducting members of the barn.  For farms with these electrical characteristics, stray voltage problems are present.  In general, the greater the currents circulating in materials connected to the earth, the greater the stray voltage problem.  In addition the cows in stalls with the greatest currents in the stall dividers are, in general, the cows that experience the most severe stray voltage problems.


Many experiments have been performed on the farms by dairy operators and stray voltage investigators.  In one type of experiment, AC is introduced into the ground to determine the impact on the cows.  Even though the number of trials is small, in all cases effects on behavior, health and production have been noted.  The health and production problems persist for a few days after the electricity is removed.  On some occasions DC has been introduced into the floor of the barn, with immediate behavioral effects.  With certain DC levels, production is improved for short periods of time, and there are improvements in behavior and in evenness of the milk let down.  Only an empirically determined DC level and polarity can produce this improvement.  Maintaining the improved condition requires continual adjustment of the DC potential.  If the cows are exposed to the DC source for a long period of time, however, negative effects begin to occur.

Over the past number of years dairy operators and electrical experts have measured significant electric currents reaching the dairy barn from the primary neutral, even when there is no electrical wire connection between the primary neutral and the barn.  These measurements have encouraged the dairy operators to take the desperate step of disconnecting the primary grounding on their farms, and sometimes even off their farms.  This mitigation method is not approved by the electric utilities and is not recommended by electrical experts.  Consequently, only a small number of cases are documented.  For 20 known cases, disconnecting the primary grounding wire had an immediate and beneficial effect on behavior, milk production, somatic cell count (SCC), water and feed consumption, and general health of the animals.  On a number of the farms records are available to document these changes.  Observations confirm a positive correlation between disconnecting the primary grounding wires and improved behavior and appearance of the dairy animals.  On some farms disconnecting the primary grounding wires has been the only means of preventing the death of the dairy animals.  Unfortunately on many dairy farms, the length of time the primary grounding wire has been disconnected is inversely related to the benefits of disconnection.  Thus disconnection of the primary neutral does not seem to be a permanent solution to the problem.

The earth has an electrical equilibrium determined by many factors:  the amount of electric current entering the earth, the relative conductivities of various regions of the earth, the location of electrical neutral connections to the earth, and the resistances of their ground rods.  When the sources of electricity are disrupted by disconnecting grounding wires, changes occur in the electrical equilibrium in the earth.  These changes, in turn, can affect the electrical currents accessing cows in a specific barn, resulting in the improvement observed by dairy operators after disconnection of grounding wires.  With time, however, the earth has a tendency to return to its long-term electrical equilibrium, and the stray voltage problem may reappear.

On one farm the Minnesota Environmental Quality Board performed an experiment to determine the benefits of disconnecting the primary grounding wires.  The results of this experiment have been interpreted differently by the dairy operators and the engineers from the electric utility.  Dairy operators noted a small but clear improvement in water consumption and milk production after the disconnection of the grounding wires, whereas the engineers concluded that no changes had taken place.  The Minnesota Environmental Quality Board chose to interpret the results similarly to the electric utilities.  The problems and the subtleties of this experiment are presented in a report prepared by the dairy operators and their consultants (Dahlberg, 1993).

Between cow contact points in dairy barns DC voltages ranging from 0.3 and 1.0 volts are common.  Experimental work in dairy barns has shown that continuous exposure to DC can affect the dairy cows either positively and negatively.  These results have encouraged dairy farmers to experiment with the use of DC for mitigating stray voltage problems.  Dahlberg and Falk (1995) identify five farms that have used batteries or DC power supplies to neutralize the DC in the ground.  Empirical methods were used to determine where and how to connect the DC source in order to produce beneficial effects.  Inappropriate connections could and did cause adverse effects.  In all cases when the appropriate connections were made improvements in milk let down, SCC, behavior and milk production were noted.  Only in one case, however, did the benefits persist.

An experiment¸ was performed in a barn with an equipotential plane in which the cows were experiencing considerable discomfort and a variety of health and production problems.  The negative terminal of a low voltage, variable DC power supply was connected to the steel grid of the equipotential plane and the positive terminal to a remote ground rod.  As the voltage output of the power supply was varied between 6 and 8 volts, a specific voltage could be found that would improve the milk let-down of the cows.  Each cow required a specific voltage setting, usually different for each cow, and voltage settings frequently had to be changed during the milking of an individual cow in order to maintain a satisfactory milk let-down.  Leaving the power supply connected and on for longer than a few hours caused an increase in discomfort for the cows.  If the positive terminal of the power supply were connected to the grid of the equipotential plane and the negative terminal to the remote ground rod, the cows were negatively affected and also demonstrated behavioral problems associated with stray voltage.  A possible explanation for these results could be that the added DC either neutralized or enhanced the DC already present in the barn from other sources, and the change in the DC environment had a positive or a negative effect on the cows.

Dairy operators have discovered that raising animals off the floor and increasing the electrical resistance between the animals and the floor can have beneficial effects.  Two specific methods have been used.  One involves the buildup of a straw pack for dry cows and calves, thus electrically insulating them from the concrete floor.  In another strategy the cows are placed in a trailer that is electrically isolated from the earth and some distance (1-2 m) above the surface of the earth.  Both of these methods have been quite successful in reducing the loss of calves and improving the health of dairy cows.  The straw pack method has been used successfully for calves in university dairy barns; it has also been useful for both calves and dry cows on a number of dairy farms.  One dairy operator has recorded success in significantly increasing milk production and improving the health of cows by using a trailer electrically insulated from the ground.  In fact, this operator has had greater success in treating mastitis by housing the sick animal on the trailer without medication than by treating the animals with antibiotics in loafing pens.  Other dairy operators have also used this method for improving calf survival and growth.  Even though the positive impact of this procedure is sufficient to encourage its use, the cost in dollars and time is too great to make it realistic on a commercial scale.  This procedure does not provide a solution to the problems on the dairy farm; it only mitigates the problems for the isolated animals.  Perhaps the greatest significance of these experiments is the  clear relationship they show between the health and production of the dairy animals and their exposure to ground currents.

An electric current trap was developed experimentally by Vulcan Engineering for the purpose of controlling ground currents on dairy farms.  The determination of trap location is based on the measurements among five copper-clad steel grids buried in the ground.  The currents measured between each pair of grids provide information on the direction of major current flow in the earth.  Once this direction has been determined, a large wire grid is buried in the earth in the path of the current flow toward the farm.  The grid is a series of wires which appear to be able to create a resonant effect for the 60Hz frequency and its harmonics.  The traps are not connected to the neutral of any electrical system; they are free-standing units not connected to any EM energy source.  When functioning as designed, the grid absorbs the electrical currents as in a resonant circuit, resulting in an increase in grid temperature.  When the grid functions as designed, grass does not grow above it and cattle will not cross it.

Of five farms reported to have a trap, three experienced an unusual improvement in the behavior, health and production of the animals after the trap was installed (Dahlberg and Falk, 1995).  The length of time that these improvements persisted ranged from a few months to approximately one year.  On two of the farms additional traps on different sides of the farm were added in the path of lesser electric currents in the earth.  Each time an additional trap was installed there were renewed improvements.  Again these improvements did not persist for more than a few months.  The fact that this approach has had some success suggests that the current traveling through the earth is accessing the farms and affecting the dairy animals.

In their attempt to maintain a profitable dairy operation, dairy operators have also experimented with burying a vertical conducting grid for redirecting the current in the earth.  They have tried trenching around animal housing and installing sheets of plastic vertically as a barrier to the electric currents in the earth.  The burying of vertical conducting grids has provided only occasional improvements.  The overall impact of the plastic barrier is still under investigation.

 The dairy operators have experienced their own health deteriorating as they work in the barn, and they have noticed the health of their families being negatively impacted.  An analysis of data from at least 400 dairy farms revealed that the greater the stray voltage problem for the dairy herd, the greater the health problems for the people living and working on the farm.  Other research shows that  similar health problems affect people all over America who live and work in EM environments, such as near power lines, substations, cellular transmitters, and radar installations (Dahlberg and Falk, 1995).  It is also the perception of dairy operators with stray voltage problems that EM energy is not only affecting people in other EM environments; it is also affecting them and their families.


Models for explaining cause and effect for EM energies in humans and animals are just beginning to develop.  Until now models have not provided a means of correlating measurements of electromagnetic parameters to the effects perceived by people or observed for animals in specific EM environments.  Research results have been mixed.  Some research has found correlations between an effect and an EM parameter and other research has not.  The large number of cases of perceived effects associated with close proximity to EM energy sources certainly attests to the existence of effects.  Throughout the development of the electric industry these perceptions have been extensively presented and described by the affected people and investigators.

As scientifically defined at present, the perceptions of effects from EM energies have been separated into five categories.  First is perceived effects  from exposure to 50 and 60 Hz electricity and primarily from the 50 and 60 Hz magnetic fields.  Of particular significance is the proximity of affected people to transmission and distribution lines.  Second is the perceived effects associated with micro- and radio-wave EM energies from radar systems, microwave transmission, radio and television transmission, and cellular systems.  Third is a well known effect referred to as electrocution.  Electrocution occurs when a large, usually short duration electric current passes through a living organism, often causing immediate death.  The fourth perceived effect is called stray voltage and has been associated with effects on both humans and dairy animals, primarily within the confines of the dairy barn.  The actual EM energy associated with the effects may include exposures to currents as well as to electric and/or magnetic fields.  The fifth category is associated with the DC transmission lines used in a few areas of the world.  Living and working in proximity to these lines has been perceived by many as causing a number of health problems.

From a quantum energy perspective, none of these EM energies can ionize atoms or molecules.  For that reason these EM energies are called non ionizing.  When molecules are not ionized, the probability for destructive effects is small.  Except for microwaves, the mechanism for effects is limited to something other than quantum interaction.  Microwaves can excite molecular energy levels and be absorbed by certain molecules in the body, causing a heating effect.  As a consequence mechanisms other than quantum interactions need to be considered.  Other mechanisms which have been suggested involve molecular polarization, which can change the charge characteristics of cells, and magnetic interactions, some of which are related to nuclear magnetic resonance and some to synergistic relationships to the variations in the earth's DC magnetic field.

Every living organism depends upon certain levels of electric currents and electric and magnetic fields for good health.  It is possible that the fields and currents in the living organism that result from the influence of external sources may change the fields and currents normally present.  According to the work of Nordenstrom (1983) this condition results in an unhealthy state.  In fact the actual interactions of internal and external electric and magnetic fields and electric currents may be very complex, quite unpredictable for a particular organism and at times very damaging.  Models for describing how EM energies are impacting the dairy cows require consideration of the various EM energies in the cows environment, the interaction of the external EM energies with the internal EM system of the cows, and the resulting effects.  Measurements of the EM energies in the cows environment reveal a complex group of electric currents and electric and magnetic fields.  Within the cow a complex EM system is required to facilitate the basic life processes.  Models for describing the interactions between the external EM energies and the cow's internal EM system are also expected to be complex.  In fact, no one model may be sufficient to explain all of the interactions.


 EM energies are vital to the functioning and well being of living organisms.  World wide research spanning nearly the entire 20th century has identified correlations between exposure to  EM energies and numerous health effects for many different living organisms.  In addition a large number of cases of perceived health effects for both animals and humans have been reported that suggest an association with the near proximity to EM energy sources such as power lines and electronic equipment.  Scientific models that support the experimental findings and research activities of practitioners have been slow to develop.  The traditional models of shock and heating have been unable to account for the research findings or the perceived health effects from exposure to various EM energies.

For stray voltage, shock is the traditional model.  The shock has been assumed to be the only electrical cause of the behavior, health, and production problems present on stray voltage dairy farms.  Dairy operators and stray voltage investigators have determined, however, that the behavior, health, and production problems of dairy cattle and the health effects for humans are present whether or not the electricity in the barn is able to produce a discernible shock.  When an existing model fails to correspond with physical reality, new models are required for consideration.  Given the information available and the complex electrical system of the cows, more appropriate models must take into account the means by which external EM energies can affect the cow's internal electrical system, and the impact of these effects on the behavior, health, and production of the cow.

The information from studies of stray voltage suggests that external EM energies interact with the cows electrical system in ways capable of producing similar effects in an entire herd, specific effects in specific cows, and multiple effects in numerous cows.  The shock model is unable to explain these interactions.  An interaction model may be more appropriate for understanding stray voltage.  The direction of future research should be toward the development of methods for studying the EM environment of the dairy cow, possible mechanisms of interactions of external EM energies with the cow's internal electrical system, and resulting effects on behavior, health, and production of the cow.

 Over a period of at least 20 years dairy operators have documented a connection between the deterioration of the health of dairy cattle and people and the electricity that is intentionally placed in the earth by the electrical distribution system.  Perhaps the greatest contribution that stray voltage discoveries by dairy operators can have is to provide for all people a picture of how a major source of EM energy can impact all of society.  No one escapes the continuous physical connection to the entire electrical system and the resulting continuous flow of electric current within their bodies.


Dahlberg, Duane A. 1993. Effects on Dairy Herd Health and Production Resulting From Primary Neural Grounding Practices: Interpretations of the Measurements on the Lusty Farm. The Electromagnetics Research Foundation. presented to the Minnesota Environmental Quality Board.

Dahlberg, Duane and Laurence Falk. 1995. Electromagnetics Ecology: Stray Voltage in the Dairy Industry. The Electromagnetics Research Foundation, Inc. January 1995..

Lefcourt, A.M., ed. 1991. Effects of Electrical Voltage/Current on Farm Animals. U. S. Department of Agriculture, Agriculture Handbook No. 696.

Nordenstrom, Dr. Bjorn. 1983. Biological Closed Electric Circuits: Clinical, Experimental, and Theoretical Evidence for an Additional Circulatory System. Stockholm.

Prepared 1997

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