Duke-American Transmission Co.

We bring together the strengths of two leading electric industry companies to build, own and operate new electric transmission facilities throughout North America.

Understanding electric and magnetic fields

EMF and you

It is a fact of life that we all are exposed to electric and magnetic fields, or EMF. Any device that uses or carries alternating current including everyday appliances, lighting and wiring, as well as power lines that serve your home creates electric and magnetic fields.

Electric fields are created by voltage (the flow of power). Magnetic fields (the force of power being discharged while electricity is moved) are created by alternating current. To illustrate, an electric field will be present around a lamp that is plugged in but not turned on. A magnetic field will be created when the switch is flipped and current flows to the lamp. When the lamp is on, EMF exists.

Scientific research

Most of the discussion and research during the past 30 years about the possible health risks of electric and magnetic fields has focused on magnetic fields. The scientific findings remain inconclusive – a direct link between magnetic fields and a higher risk of negative health effects has not been firmly established. The electric industry has monitored scientific research into possible health effects of electric and magnetic fields and funded more than $100 million in research.

The vast majority of findings have produced weak or inconsistent associations between electric and magnetic fields and a higher risk for negative health effects. The scientific community has generally characterized the findings, taken as a whole, to show no consistent association between magnetic fields and a risk of adverse health effects.

We continue to support research through programs including those conducted by the Electric Power Research Institute, the World Health Organization and others, and are committed to sharing any additional research findings.

HVDC power lines produce static magnetic fields

Since high-voltage direct current (HVDC) transmission lines use direct current, or DC, they produce static magnetic fields.

Static magnetic fields are created by the steady flow of electricity, such as on a DC power line. They are measured in milligauss (mG). The earth has a natural static magnetic field ranging from 300 to 600 mG as a result of currents flowing deep within its core.

While the design and operating characteristics of lines vary by project, the range of levels that would be produced by a HVDC transmission line are estimated at about 100 to 570 mG – similar to the earth’s natural magnetic field.

Can static electric fields affect my health?

National and international scientific agencies responsible for public health have convened multidisciplinary groups of scientists to evaluate the research and to determine if health effects are associated with exposure to DC electric and magnetic fields.

These groups include the World Health Organization, the National Radiological Protection Board of Great Britain, and the International Agency for Research on Cancer. These organizations came to the following conclusion: There are no known adverse health effects associated with low levels of static electric or magnetic fields such as those associated with DC transmission lines.

EMF and voltage conversion substations

HVDC projects include an AC/DC conversion substation at each end of the line. These stations are a source of alternating magnetic fields. Many variables affect the strength of a magnetic field around an electric substation: the amount of electric current flowing and the configuration or arrangement of the substation. When it comes to EMF, the strength and intensity of electric and magnetic fields quickly decrease as you move away from their source.

Additional resources

  • Electric Power Research Institute:  http://emf.epri.com
  • National Cancer Institute:  www.cancer.gov and type “EMF” in the search tool.
  • The National Institute of Environmental Health Sciences – National Institutes of Health: www.niehs.nih.gov and type “EMF” in the search tool.
  • National Research Council “Possible Health Effects of Exposure to Residential Electric and Magnetic Fields”: www.nap.edu and type “electric and magnetic fields” in the search tool to download a free PDF of this book.
  • World Health Organization: www.who.int/peh-emf/en