60 Hertz (Hz) electric and magnetic fields (known as “EMF”) are produced by all devices which use, carry, or produce electricity, including household appliances, office equipment, power lines, and wiring in buildings. These are actually two separate fields; the electric field is caused by the voltage on a conductor, while the magnetic field is caused by the current flowing in a conductor.
For power lines this means that the electric field is relatively constant (since the voltage of a power line does not fluctuate), while the magnetic field varies throughout time depending on the current flowing in the power line (this is a function of how much electricity our customers are using at any given time). The strength of both fields decreases as distance from the source increases. In addition, the electric field is easily shielded by solid objects such as buildings or trees, while the magnetic field is generally not shielded by these objects.
Due to these factors, and the fact that high voltage power lines are placed on poles high in the air, the field strengths at ground level near high voltage power lines, particularly the magnetic field strengths, are often similar to those encountered in close proximity to common household, school, and office electrical appliances.
There have been scientific studies on the potential health effects of EMF for more than 25 years. For a more thorough understanding of this research we recommend reviewing web sites of organizations such as the National Institute of Environmental Health Sciences
and the World Health Organization
(WHO). The WHO website, as of March 2017, states, “Extensive research has been conducted into possible health effects of exposure to many parts of the frequency spectrum. All reviews conducted so far have indicated that exposures below the limits recommended in the ICNIRP (1998) EMF guidelines, covering the full frequency range from 0-300 GHz, do not produce any known adverse health effect.”
APS recognizes that research into potential health effects from exposure to EMF is ongoing and we try to respond appropriately. We follow this research closely and over the years we have helped to fund, and have participated in some of this research. We also include EMF considerations into the design and siting of new power lines or structures. In addition, we can provide educational materials and field strength information on existing and proposed power lines as necessary. All of our construction standards and practices meet or exceed the nationally accepted standards of the National Electrical Safety Code.