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Electric and Magnetic Fields (EMF)

Eversource's mission is to reliably and safely deliver electric power to its customers at a reasonable price and in a responsible manner. The following information will help you better understand the issue of potential health effects from exposure to electric and magnetic fields (EMF) and what Eversource is doing on the issue. Read our EMF informational flyer.

The issue
EMF background information
Electric fields and shocks
Eversource's commitment to safety & health: What we're doing
Where to get more information

The issue

While everyone is aware of obvious safety issues related to electricity, such as electric shock, some scientists have raised questions about possible health effects from exposure to EMF near power lines, electric appliances and other sources.

Watch a fact-filled, easy-to-understand video (755 kbps or 141 kbps, 9 mins.) about sources of EMF, recommendations of scientific organizations and ways in which electric utilities can design transmission lines to reduce magnetic field levels at the edges of rights-of-way.

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EMF background information

EMF are produced through the generation, transmission, and use of electric power. We encounter alternating current (AC) EMF throughout our daily activities at work and at home. Common sources of EMF in our homes include fields generated by appliances, the home wiring that brings power to those appliances, and the nearby distribution lines that supply electricity to our homes.

The electric power delivery system in the United States is constructed primarily of 60 hertz (Hz) AC transmission and distribution lines. High-voltage transmission lines move bulk power from power plants to distribution substations, and from there, lower-voltage distribution lines deliver electricity to our homes and businesses.

As you may remember from science class, electric fields are produced by voltage, while magnetic fields are produced by currents. Voltage is the pressure behind the flow of electric currents.

AC electricity alternates back and forth -- 60 times per second, or at 60 Hz. Because the electric and magnetic fields associated with AC electricity are at the very low end of the electromagnetic spectrum, they are called "extremely low frequency" (ELF) fields.

Electric fields and shocks

Electric power transmission lines produce an electric field in the space between the line conductors and the earth surface. Electric field levels near transmission lines depend upon the voltage on the conductors, the distance to the conductors, the spacing between the conductors, and the presence of adjacent transmission lines. In general, electric fields at ground level are highest beneath the line where it sags closest to ground and decrease with distance, i.e., horizontally away from a line or where the line conductors are higher above the ground. This electric field can also be distorted by nearby objects such as walls, vegetation, people and animals.

Objects, including people, in an electric field receive a small induced charge that is proportional to the size/shape of the object and the level of the electric field. Most often this charge drains imperceptibly from the object to the earth where the object is in contact. But if the object has a poor electrical contact with the earth, and especially with larger objects and larger electric field levels, a person making contact with the object may perceive a small shock. Such shocks are not in themselves harmful, but may be unpleasant and startling for someone who is unfamiliar with them. The effect is similar to a person shuffling his shoes on a carpet, and then touching a door knob in his home.

The shock level and its perception are governed by a number of factors. These factors include:

  • Size of the object with a poor connection to earth
  • Electrical connection to ground of grounding person or object
  • Area of skin contact
  • Electric field level (affected by line voltage, line geometry and position relative to the transmission line and any distorting objects)
  • Soil type and water content
  • Atmospheric conditions
  • Personal physiology

Generally, only transmission lines operating at 345,000 volts (the highest ac transmission voltage in New England) or higher (up to 765,000 volts in some parts of the U.S.) produce electric field levels sufficient to produce small shock perceptions. And considering the low probability of the other object circumstances needed to produce a perceptible shock, small shock perceptions by the general public are relatively rare even under transmission lines with the highest electric fields.

However, large objects such as tractor trailers, campers and RVs, greenhouses, tents, irrigation systems, etc., if grounded poorly, could produce perceptible shocks underneath lower voltage transmissions lines (such as 115-kV transmission lines), but not off the right-of-way. If itís necessary to keep a large object on the right-of-way and acceptable to the utility, grounding of such objects will usually eliminate all shock perceptions.

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Eversource's commitment to safety & health: What we're doing

Eversource's efforts to address the issues raised by research and the concerns of some customers are focused on the following activities:

  • Providing information - Eversource has assigned employees to monitor EMF developments, provide information, respond to customer and employee questions, and recommend actions to management. We rely on the consensus of scientific organizations such as the NIEHS, the International Agency for Research on Cancer and the World Health Organization, which have reviewed the large body of scientific research regarding EMF and health. At the request of electricians and homebuilders, we can also provide information on home electrical wiring and service grounding practices that can reduce magnetic field levels.
  • Taking measurements - Company representatives may take measurements of magnetic fields for customers upon request. We provide these measurements to help our customers understand the magnetic field levels associated with various sources in their environment.
  • Designing new projects - Eversource's policy for new transmission line construction is to investigate practical no- and low-cost engineering approaches for reducing magnetic field levels at and beyond the edges of rights-of-way which may be adjacent to residential areas, schools, licensed day-care facilities, licensed youth camps, or public playgrounds. This policy is consistent with a recommendation by the World Health Organization and with the policy expectations of some siting authorities.

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Where to get more information

You may contact Eversource at EMFQuestions@eversource.com or 877-993-6377.

Additional information about EMF is available from:

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