Electric and magnetic fields are both components of an electromagnetic field (EMF). Electromagnetic fields are invisible forces in our environment that result from natural and manufactured sources. They are created whenever electricity is present. Canadians are exposed to EMFs at extremely low frequencies daily through items such as household wiring, lighting, hairdryers, computers and power tools. According to Health Canada, the term “extremely low” describes any frequency below 300 Hertz. EMFs produced by power lines fall into this category.
ENMAX understands some individuals may have concerns regarding electromagnetic fields (EMF). Both Health Canada and the World Health Organization have not found any conclusive evidence indicating that low level long-term exposure to EMFs from power lines cause adverse health effects.
ENMAX continually monitors this topic and stays up to date on information related to EMFs through our work with the Canadian Electricity Association’s EMF task group. To maintain an ongoing dialogue with our customers and the public, ENMAX offers EMF information consultation and in-home magnetic field measurements free of charge.
Electric fields are produced by voltage, which can best be compared to the pressure of water in a pipe. They are measured in kilovolts per metre (kV/m). There are electric fields wherever voltage is present, such as when an appliance is plugged in, even if it is turned off. The higher the voltage, the higher the electric field. Electric fields are weakened by objects like buildings and trees, and the strength of electric fields decreases as distance from their origin increases.
Magnetic fields are produced by electrical current, which is comparable to the quantity of water flowing through a pipe, and are measured in microtesla (uT) or milligauss (mG). They are only present when power is flowing through a wire, like when an appliance is turned on. The more current flowing through a wire, the higher the magnetic field. Magnetic fields are not weakened by objects like buildings and trees; however, the strength of magnetic fields decreases as distance from their origin increases.
Yes, the earth produces EMFs, mainly in the form of direct current (also called static fields). Electric fields are produced by thunderstorm activity in the atmosphere and magnetic fields are thought to be produced by electric currents flowing deep in the Earth's molten core.
Generally, the strongest EMFs around the outside of a substation come from the power lines entering and leaving the station. The strength of the EMFs from transformers decreases rapidly with increasing distance. Beyond the substation fence, the EMFs produced by the equipment within the station are typically indistinguishable from background levels that naturally occur in the earth.
Electric fields are shielded by the grounded cable shield; however, magnetic fields will still be present.
For further information, please call ENMAX at
email us or visit these websites:
National Institute of Environmental Health Sciences
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