Ground Currents - An article by Duane Dahlberg, Ph D with references

www.mikeholt.com/news/archive/html/17/Ground_Currents_09-18-2002.htm
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GROUND CURRENTS: An important factor in electromagnetic exposure

Duane A. Dahlberg, Ph.D.

INTRODUCTION

Life on this earth has developed and is maintained through the use of
both electromagnetic (EM) energies and chemicals. In general, both EM
energies and chemicals are required for the continued well being of
living organisms. In the modern industrial era we have also
experienced negative consequences from the intake of certain
undesirable chemicals and exposure to unwanted EM energies. The
acceptance and understanding of adverse effects from undesirable
chemicals is now quite universal; however, there seems to be a
reluctance to accept the possibility of adverse effects from
disturbing EM energies.

The stray voltage problem in the dairy industry has been helpful in
understanding the relationship between exposure to EM energies and
health. The term stray voltage is applied to certain electrical
conditions in the housing of confined livestock, and to associated
behavior, health, and production effects on dairy animals. Recent
investigations also show an association between the presence of stray
voltage problems and the health of people who live and work in these
livestock facilities. The source of the electricity involved in stray
voltage problems is the current entering the earth from the power
system and, more recently, from cellular transmitters. These currents
in the earth are intentionally present, because of the electrical
distribution system's use of the earth as a current-carrying
conductor, and also unintentionally present, in the case of electrical
problems on farms (Dahlberg and Falk 1995).

The issue of health effects from exposure to EM energies is mired in
controversy because of inconsistencies in research data and the
inability of present models to explain the empirically observed health
effects. From these inconsistencies it is tempting to draw the
conclusion that even if a connection may exist between EM energies and
certain types of health problems, that connection is weak and probably
requires little attention, given the large number of other
environmental health risks to which we are exposed. It would be
unwise, however, to prematurely minimize the effect of exposure to EM
energies. There are a number of factors that may seriously limit the
reliability of the existing research: EM energy exposure is very
complex and difficult to measure; clearly defined mechanisms are
elusive; the electric and magnetic systems of the human body are not
well understood; and a control space is in general unavailable.
Together these factors make research very difficult and increase the
potential for inconsistencies in research results. At the same time,
empirical evidence from field investigations continues to show
associations between a number of EM parameters and a disturbing number
of health effects in humans and animals.

GROUND CURRENTS
All living organisms are exposed to numerous sources of EM energy. The
earth-atmosphere system produces electric currents and electric and
magnetic fields. The most evident are the magnetic field of the earth
and the electric field of the atmosphere. These are continuously
present and especially the electric field of the atmosphere is
dynamic. There are also pulses of current in the earth from lightning
strikes, induced currents from the solar wind, direct currents from
galvanic processes in the earth, and currents from movements of the
earth's crust. The currents in the earth from these sources are, in
general, much smaller than those from technological sources. The
exceptions are currents from lightning strikes and occasional direct
currents, primarily induced at the geomagnetic poles by a surge of
solar, charged particles reaching the earth's atmosphere. The most
common term used for these currents is earth currents.

There is also increasing exposure to EM energies from technological
sources. Some of these sources are relatively predictable and easily
measured, such as 60 Hz magnetic and electric fields from distribution
lines and home wiring and appliances. Stray voltage investigators have
discovered that a major source of EM energy interacting with the dairy
cow is electric current in the floors of barns and in the ground
beneath the floors. The levels of these currents are difficult to
predict and very difficult to measure accurately. Researchers have
come to realize that livestock facilities are not the only place where
these currents exist. There is potential for all life to experience an
exposure to EM energies from these electric currents in the earth, in
addition to those from the more obvious sources mentioned above.

In this paper, electric currents in the earth that emanate from
technologically developed systems are called ground currents. Ground
currents are a mix of DC and AC, both of which can be continuous
and/or pulsed. The present discussion addresses ground currents that
arise both from distribution systems of the electrical utilities and
from electrical systems of consumers. These currents in the earth are
the product of the design of electrical systems and not specifically
associated with the use of underground electric cables. It is
important to emphasize that in limiting this discussion to ground
currents, this paper does not preclude possible effects from other
sources of EM energies. Clearly effects are related to the total EM
energy exposure.

SOURCES
Farms, businesses, and homes have self-contained, closed electrical
systems except for the connection of the electrical utility (primary)
neutral to the user's (secondary) neutral. Several electrical problems
in the user's electrical systems can lead to aggravating ground
currents. Some of these problems are electrical faults, imbalances in
the user's electrical system, malfunctioning of motors, and wiring
errors. Each of these conditions can cause electricity to be in the
secondary grounding system and, therefore, cause electric current to
be in the ground. Because the neutral of the secondary system is
normally grounded, and frequently grounded through metal water pipes,
there is always the possibility of ground currents resulting from the
normal use of electricity. Since the user's electrical system is
structured to use wires to carry all the current, however, it will
produce minimal levels of ground currents. For some applications the
neutral and ground wires are totally separated from each other. If the
neutral and ground wires are separated, no current reaches the earth
from the secondary system unless an electrical fault exists.

Electrical distribution systems serving both urban and rural areas are
usually at 7200 V ac and connect the consumer to a substation. The
single-phase distribution lines consist of a high voltage wire and a
neutral wire; these two wires provide the complete path required in
any electrical circuit. These wires may be overhead on poles or buried
in the earth. When the distribution system was first conceived, it was
totally closed, with no connection to the earth. Early in the
expansion of the electrical distribution system in rural America
(during the 1930's), the utility industry made a decision to change
the originally ungrounded distribution system to a grounded system.
This change allowed a portion of the neutral current to return to the
substation through the earth. The neutral wire of the distribution
system is connected to ground rods and/or other conducting materials
in the earth (such as water pipes and systems)
in order to provide a path for the current to be able to get into the
earth. Grounding became a common practice in the utilities'
distribution and transmission systems.

In addition to causing some of the neutral current of the distribution
system to return to the substation through the earth, the grounding of
the neutral wire connected everything in and on the earth to the
distribution system neutral. During the intervening years since the
distribution system was first grounded, demands and loads have grown
rapidly, and currents in the wires have increased beyond their
designed capacity, resulting in an ever-increasing need for the earth
connection. Electric currents flow through wires, objects, and the
earth according to their respective conductivities. Today the earth
has a higher conductivity than the utility's neutral circuit return
wires, and therefore, carries the majority of neutral current
returning to the substation (Gonen 1986; Morrison 1963, Hendrickson,
Michaud, Bierbaum 1995). Consequently these neutral currents in the
earth are the largest contributor to ground currents

In providing electrical energy to the consumer, the utility connects
its system to the primary windings of a transformer, and the user's
system is connected to the secondary windings of the same transformer.
A transformer has the function of isolating electrical systems and
increasing or decreasing voltages. In this case, the transformer
reduces the 7200 V on the primary system to 120 and 240 V on the
secondary system. Both the primary and secondary electrical systems
are designed to function without any physical electrical connection
between them.

At some point in the expansion of electrical distribution systems, the
neutral wires of the primary were connected to the neutral wires of
the secondary electrical system. Thus the secondary system was no
longer isolated from the primary system. Today this is a common
practice throughout the electrical distribution network. The stated
reason for this connection is to provide a safer electrical system for
both the consumer and the electrical utility personnel. Certainly the
potential for electrocution is a significant safety concern to
electric utilities. An even more important reason for the
interconnection, however, may be to provide additional grounding
points for the utility neutral current to enter the earth for its
return to the substation. These additional grounds decrease the net
resistance of the earth path as compared to the resistance of the
neutral wire, and therefore increase the fraction of neutral current
in the earth. To solidify the earth connection, and to insure a
sufficiently low grounding resistance, the neutral has been connected
to water pipes and water systems. Present codes frequently require
water pipes to be part of the grounding system, and, therefore to
carry electric current, especially from the primary neutral. The
user's grounding network has become a fundamental part of the
electrical distribution system. The consequence of these practices and
code requirements is an increase in current entering the earth where
animals live and people live and work. It also increases the
connection of all living organisms to the electrical distribution
system (Raloff 1993; Burke 1991).

The conductivity of specific earth materials determines the locations
and magnitudes of current in the earth. Water saturated soils and
bodies of water, such as wetlands, lakes, streams, and rivers, are
likely to carry more current than dry soil. Conducting materials
buried in or on the earth have the potential of being formidable
carriers of electrical current. Natural gas and oil pipelines are good
conductors of electricity and are known to carry sizable currents
(Lathrop 1978). Ground currents traveling in these pipes also move on
and off of them, through the earth, to ground rods and other
conductors in the earth. The presence of these 60 Hz currents on
pipelines increases the need to apply direct currents to the pipes to
prevent corrosion. The consequence of protecting them from corrosion
is to increase the quantity of direct current in the ground current
mix. Substantial grounding grids are buried in the earth below
substations. Electric currents in the ground that emanate from the
grounding of the neutrals of the distribution lines and other sources
converge on these grounding grids. Consequently greater ground
currents are present near substations and in structures in their
immediate vicinity. Ground currents also have a greater probability of
being present in direct paths between large users of electricity and
between these users and the substation. Rural developments increase
the number of grounds on the utility neutral, and thus increase the
ground currents reaching nearby dairy operations.

DESIGN DECISIONS
A substantial quantity of information has been generated from studies
of electrical problems in both urban and rural areas to substantiate
the presence of ground currents in structures in and on the earth, and
the fact that both humans and animals are exposed to these currents.
This exposure of living organisms to ground currents has come about
primarily because of engineering design decisions. A number of factors
have influenced these design decisions.

One factor is a concern for the dependability of the electrical
system. If only one power source were providing the electrical energy
for the distribution system, failures in the power source could, of
course, disrupt the availability of electricity. Therefore, the
majority of electrical utilities in the United States are connected
together, allowing power to be transferred among utility systems.
interconnecting power sources and individual distribution systems
requires careful matching of the phases of the various sources and the
users. As individual electrical utilities join together, transferring
electricity according to demand and availability, the earth becomes a
common reference. As a common reference, the ground, requires that all
neutrals be interconnected, thus increasing the potential for ground
currents.

Economy of scale has also been applied in the generating of
electricity, resulting in larger power plants capable of providing
electricity to a larger numbers of users and at a lower cost. There
are numerous changes required in the national distribution of
electricity in order to utilize the larger power plants. In some cases
the larger power plants do not easily change power levels to
accommodate changing loads. Additional smaller plants are required in
the system to provide for changing demands. In the case of 60 Hz
electrical power, storage is not feasible. If the demand for
electrical energy falls below the output of power plants, it may be
necessary to shunt some electric current into the earth until the
output is adjusted to match the demand. Current that is shunted into
the earth adds to the ground current.

A second factor is associated with the economics of electrical
distribution. According to utility engineers, the resistance of the
neutral wire causes significant voltage drops along the lines,
requiring frequent voltage adjustments. As the demand for electricity
has increased and as the number of users has grown, the distribution
lines have been extended to supply the increased number of users. The
greater the electrical current on these lines, obviously the greater
the loss of electrical energy and the greater the voltage decreases.
Experience indicates that using the earth to carry a portion of the
current reduces the losses and consequently reduces the need for as
many voltage adjustments. Thus the previously ungrounded electrical
distribution system has become a multi grounded system which uses the
earth to carry a fraction of the neutral current (Mairs 1994).

A third factor influencing design decisions is the expressed
requirement for having an electrical distribution system safe from
electrocution or other bodily harm. Electric utilities are especially
concerned about the potential for electrocution from fallen electric
lines and the effects of lightning strikes on electrical distribution
systems. With a well-grounded neutral, the current from a fallen line
will travel in the earth, causing a circuit breaker to open and
disconnecting the high voltage line from its source of current. Since
the ultimate destination of the current in a lightning strike is the
earth, a well-grounded neutral is most likely to attract the bolt of
lightning, and the grounding wires provide the path into the earth.
The need to protect people and property is an important issue; of
equal importance is the fact that the grounding of the neutral wire
changes the role of the high voltage wire. Anyone who is directly or
indirectly connected to the earth will certainly be killed if contact
is made with the high voltage wire, and a continuous electric field is
established between the earth and the high voltage line. Therefore,
the present multi grounded distribution system requires that everyone
must avoid any contact with the high voltage wire, and all living
things are constantly exposed to this electric field. In contrast, a
totally ungrounded system has the advantage that a person could stand
on the ground and touch either the neutral or the high voltage wire
(but not both) and not be electrocuted, and the electric fields are
more confined the region of the two wires. For the previously
ungrounded system, lightning arrestors were used to alleviate the
destruction of electrical equipment in a lightning strike. The
lightning arrestor connected the electrical distribution lines to the
ground if a lightning strike should occur, and shunted the current to
the earth to prevent damage.

GROUND CURRENT INTERACTIONS
The grounding practice in the utility industry forces all living
organisms to be continuously in physical contact with the electrical
distribution system. The extensive grounding of the neutral in the
distribution system also forces electrical currents to be present to a
greater or lesser degree in all materials making up the environment of
living organisms. Of course the living organisms, since they are
themselves conductors of electricity and in contact with materials
carrying electric currents, are basically plugged into the electrical
circuitry of the distribution system.

The use of water pipes and other conductors in the earth to carry the
neutral current of distribution systems has the effect of decreasing
the current in the neutral wire. In addition, when unshielded
distribution wires are buried in the earth, the neutral slowly
corrodes, also increasing the amount of the neutral current in the
earth. If the neutral and the high voltage wires carry the same
current, the magnetic fields in the vicinity of the lines are
relatively small, because the magnetic fields of the two lines nearly
cancel each other. When the current in one wire is much less than in
the other, the magnetic field is only partially canceled. This
condition greatly increases the magnetic field in the area of
distribution lines and enhances the range of these fields. In homes
and businesses there is also an increase in the 60 Hz magnetic fields
from the ground currents in water pipes and other conducting material.
This condition is very effectively presented in a paper prepared for
Austin, Texas {Preston, 1989)

Alternating current in the ground sets up alternating electric and
magnetic fields. These electric fields give rise to electrical
potentials that can induce currents in living organisms in contact
with the ground. Alternating magnetic fields, by their very nature,
also produce currents in conducting materials. Electric currents in
living organisms, regardless of the mechanism that may produce them,
are indistinguishable from one another. The currents simply access the
body differently. In addition to the possibility of inducing an
electric current in the body of living organisms, the electric and
magnetic fields may independently or synergistically interact with
parts of the body. Complicating the understanding of the interaction
of these ground currents with living organisms is the effect of earth
materials on the 60 Hz current entering the earth. The non-linear
characteristics of the earth distort the 60 Hz sine wave, even
affecting the natural processes that produce direct current in the
earth. Thus ground currents from the power system are transformed
into some combination of 60 Hz, harmonics, and direct currents.

An assumption has been made, in the design of the electrical
distribution system, that the grounding of the system creates a
constant electrical potential on the earth's surface. This is called
an equipotential plane in the dairy industry. Using that assumption,
all living organisms are living on an equipotential plane, connected
to the neutral of the electric distribution system. To justify this
ground connection, it is also assumed that an equipotential plane is
an electrically safe place to be. The stray voltage problems in the
dairy industry, however, have shown that when the neutral of the
distribution system is connected to the earth, the earth is neither a
plane of constant electrical potential nor an electrically safe place.
Livestock producers are especially aware that lightning or a fault in
a distribution line can kill animals if they happen to be in the path
of the electric current in the ground. Dairy operators are frequently
required by state codes to construct equipotential planes in their
barns as a means of avoiding electric shocks for the cows.
Unfortunately the equipotential plane is a good conductor which
attracts a greater percentage of the ground currents, causes the cows
to be exposed to greater continuous currents, and frequently increases
stray voltage effects (Dahlberg and Falk 1995).

Surveys and farm evaluations and investigations have provided a
significant body of information concerning the effects of ground
currents (Hartsell, Dahlberg, Lusty, and Scott 1994; Dahlberg and Falk
1995; Marks, Ratke and English 1995; Kelly 1998). As mentioned
previously, the main documentation of electrical effects in dairy
barns historically involves ground faults. When electric current
enters the earth from a high voltage wire, the event is called a
ground fault. The high voltage wire can be from either the primary or
the secondary system. Usually discussions of ground faults center on
problems in the secondary system. Well-known effects from ground
faults include behavioral, health, and production problems for
confined livestock, such as dairy animals, and both human and animal
electrocution (Dahlberg and Falk 1995).

On dairy farms, current in the ground is associated with behavioral,
health and production effects in cows. It is very important to carry
this association to the next step, which is the determination of how
these currents interact with the cow to produce the physical effects.
The presence of ground currents implies long-term, continuous exposure
to low-level electrical currents. Worldwide research and
investigations of both animal and human health problems in dairy barns
have demonstrated that small continuous currents (as low as a fraction
of a microamp) can affect well being. Bjorn Nordenstrom, among others,
has suggested models that portray the bodies of living organisms as
having electric circuits with small currents actually controlling life
(Nordenstrom 1983). Appropriate electric currents of small magnitudes
within the circuits of the body are vital to good health. The bodies
of living organisms generate these currents and naturally provide the
magnitudes that afford good health.

Using Nordenstroms models, one can imagine that exposure to an
electric and magnetic environment could affect the currents in the
circuits of the body, either positively or negatively. The medical
community has utilized this positive potential in a number of ways.
Negative changes caused by these currents, however, would require the
body to correct the change. Such an event could be classified as a
stress on the body. It would be logical to conclude that exposure to
certain electrical conditions can be equivalent to initiating a
stress. If the currents in the floor of the barn set up an electric
and magnetic environment that causes inappropriate currents in the
body of the cow or the human, the experienced effects would likely be
similar to those caused by other stresses. Unfortunately, the research
community has been reluctant to investigate this source of stress on
animals and humans. The traditional research model continues to assume
that negative health effects are possible only in the presence of
physical shock.

CONCLUSIONS
The health of the environment is a determining factor in the health of
all life within that environment. Under some circumstances, human
ingenuity in the treatment of illnesses can delay and reasonably
mitigate the effects of an unhealthy environment. Under other
conditions or over time, however, the effects of an unhealthy
environment may slowly or rapidly wear on the health of life in that
environment. A world population of approximately 6 billion people,
with no new frontiers, is extremely vulnerable to unhealthy changes in
the environment. This world condition is a compelling reason for
seriously monitoring changes in the environment and constantly
assessing the effects of those changes.

An important environmental change, and one that has escalated since
its inception over a century ago, is the addition of EM energies to
the environment. The extensive use of the earth to carry electric
current is the most dramatic and least understood of these additions.
Even though the earth has been used for all these years as a sink for
electrical current, little is known about the paths of these currents
or the effects of the currents on either the animate or inanimate
world. In fact, shock-effect models still dominate the regulatory
agencies' concept of how EM energies interact with life. Even in
decisions regarding research directions, these inadequate models are
still applied. Research from around the world has shown the need to
recognize new models that are consistent with the electrical nature of
living organisms and the complexity of our environment. Stray voltage
research and the ground current connection have provided valuable
insights into the relationship between exposure to EM energies and
effects in humans and animals.

For 50 years professionals in the dairy industry have known that
electric current in the earth from a ground fault, occurring on or off
a dairy farm, can seriously affect the health and production of dairy
cows. Today we live with an electrical distribution system that has
been designed to put electric current into the ground. The design of
the electrical distribution system has created a perpetual ground
fault capable of impacting all life. Perhaps it is time that we heed
the warning cries of dairy operators.

REFERENCES

Burke, James J. 1991. "Controlling Magnetic Fields in the Distribution
System". Transmission & Distribution. 43:12, pp 24-27, Dec. 1991

Dahlberg, Duane A. 1986. "Electromagnetic Synergistic: A Depressing
Problem in the Dairy Industry." Concordia College, Moorhead, MN.
Research Paper

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

Gonen, Turan. 1986. Electric Power Distribution System Engineering.
Hightown, NY: McGraw Hill

Hartsell, Daniel, Duane Dahlberg, Dave Lusty, and Robert Scott. 1994.
"The Effects of Ground Currents on Dairy Cows: A Case Study". The
Bovine Practitioner. September 1994. p 71-78

Hendrickson, R.C., Mike Michaud and Alvin Bierbaum. 1995. Survey to
Determine the Age and Condition of Electric Distribution Facilities in
Minnesota: Report 1: Analysis of Overhead Distribution Feeder Testing
Data. Minnesota Public Utilities Commission. May 18, 1995

Kelley, Frank J. 1998. Attorney General Frank J. Kelley's Complaint
Against Consumers Energy Company Related to Stray Voltage. Case No.
U-11684. State of Michigan. April 1998

Lathrop, David T. 1978. "Alternating Current Natural Potentials on
Underground Gas Piping Systems". Materials Performance. 17:2. pp
13-17. 1978

Mairs, Dan. 1994. "Overview of Distribution Systems". Team of Science
Advisors Meeting. Minnesota Public Utilities Commission. Radisson
Hotel. St. Paul, MN. December 12-13, 1994

Marks, T.A., C. C. Ratke, W. O. English. 1995. Veterinary and Human
Toxicology. 37:2. p 163-172

Morrison, C. 1963. "A Linear Approach to the Problem of Planning New
Feed Through Points Into a Distribution System." AIEE Trans. III.
(PAS) Dec. 1963 p 819-832

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

Preston, Eugene G., P.E. 1989. "EMF EFFECTS FROM URD SYSTEMS".
presented at American Public Power Association Engineering &
Operations Workshop, Washington, D.C. March 15, 1989

Raloff, Janet. 1993. "EMFs Run Aground". Science News. 144, pp
124-127, 1993

REVISED: JANUARY 2000

Duane A. Dahlberg, Ph.D. Consultant
[hidden email]
The Electromagnetics Research Foundation, Inc.
1317 6th Ave. N.
Moorhead, MN 56560

218 233-8816

Copyright © 2002 Mike Holt Enterprises,Inc.
1-888-NEC-CODE (1-888-632-2633)

I ran across this looking for something else the other day, about
grounding. I'm just betting this site has all kinds of things that
could be made useful/applicable to humans as well as shortwave/radio.

http://www.smeter.net/grounds/grounds.php