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

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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; on 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 1994; Dahlberg and Falk

1995; Marks, Ratke and English 1995; 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, 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 ce 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, , Duane Dahlberg, Dave Lusty, and . 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, J. 1998. Attorney General J. Kelley's Complaint

Against Consumers Energy Company Related to Stray Voltage. Case No.

U-11684. State of Michigan. April 1998

Lathrop, 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. , MN. December 12-13, 1994

Marks, T.A., C. C. Ratke, W. O. English. 1995. Veterinary and Human

Toxicology. 37:2. p 163-172

on, 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

dahlberg@...

The Electromagnetics Research Foundation, Inc.

1317 6th Ave. N.

Moorhead, MN 56560

218 233-8816

Copyright © 2002 Mike Holt Enterprises,Inc.

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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