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About electric and magnetic fields

Electric and magnetic fields (EMFs) are part of our everyday lives and are created in varying degrees by electrical devices and power lines.

On this page:

    SRP strives to ensure our customers' safety by staying abreast of the latest research about EMFs. In addition, we support and fund EMF-related medical and scientific research, primarily through the Electric Power Research Institute (EPRI) .Open new site.


    Since the 1970s, there have been several thousand scientific papers Open new site. published and over two dozen expert panels have reviewed the research.

    EMFs have not been established as a cause of any disease or illness. With regard to cancer, the U.S. National Cancer Institute (one of the National Institutes of Health) has concluded that "no consistent evidence for an association between any source of non-ionizing EMF and cancer has been found." Additional informationOpen new site.  is available from the National Cancer Institute.

    The World Health Organization (WHO)Open new site.  has reviewed the available scientific research and stated that, "based on a recent in-depth review of the scientific literature, the WHO concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields."

    Sources of EMFs

    Electric and magnetic fields are produced by various electrical devices, many of which we use daily. Electric fields are produced when wires are energized (typically when a device is plugged in), while magnetic fields are only produced when current is flowing through wires (typically when a device is turned on). Together, these are referred to as EMFs. The strength of an EMF decreases significantly as distance from the source increases.

    Home and workplace

    Exposure to magnetic fields from electric power sources occurs during common activities at home and virtually everywhere we go, including places of work and school. Sources of exposure include any electrical device, appliance or other equipment during operation, in addition to building wiring.

    Magnetic fields from common household appliances (mG)1

    Electrical device 6" from source2 1' from source 2' from source 4' from source
    Hair dryers 1-700 1-70 10 1
    Vacuum cleaners 100-700 20-200 4-20 1-10
    Microwave ovens3 100-300 1-200 1-30 2-20
    Irons 6-20 1-3
    Televisions - 7-20 2-8 4

    Power transmission and distribution lines

    Transmission and distribution lines, essential components of the electrical grid, deliver power to neighborhoods, businesses, and homes. Power lines can be located overhead or underground. Peak EMF levels resulting from power lines can vary considerably depending on the amount of current carried by the line, whether the line is located overhead or underground, and the distance from the power line.

    Typical EMF levels near SRP power lines (mG)4

    Location EMF strength
    Directly under overhead transmission line 5 to 100
    100 feet away from overhead transmission line 1 to 20
    Directly over underground distribution line 6 to 30
    20 feet away from underground distribution line 2 to 10

    EMF guidelines

    There are no federal or State of Arizona requirements to limit public exposures to 60 Hz EMFs. Some guidelines established by international expert groups include:

    • 2,000 mG for the general public and 10,000 mG for occupational settings, International Commission on Non-Ionizing Radiation Protection, updated 2010, see tables 3 and 4 Open new site..
    • 9,040 mG for persons in unrestricted environments, or "general public exposure," and 27,100 mG for persons permitted in unrestricted environments, or "occupational exposure." See IEEE C95.1-2019, "IEEE Standard for Safety Levels with Respect to Human Exposure to Electric, Magnetic, and Electromagnetic Fields, 0 Hz to 300 GHz,"  Table 2.


    Customers who have questions regarding EMFs may email SRP Consumer Affairs at ombuds@srpnet.com or call SRP Consumer Affairs at (602) 236-2196 (602) 236-2196 .

    1EMF: Electric and Magnetic Fields Associated with the Use of Electric Power, National Institute of Environmental Health Sciences, National Institutes of Health, 2002. In the U.S., the unit of measure for a magnetic field is the gauss (abbreviated as G), with exposure expressed often in milligauss, or mG (1/1000th of a gauss). The international unit for a magnetic field is the tesla, with exposures usually expressed in units of microtesla (μT); one μT is equal to 10 mG. Most of the fields experienced in daily life are anywhere from 1 to 10 mG but can be up to 1,000 mG near electrical appliances and equipment.
    2A dash (–) means that the magnetic field at this distance from the appliance in operation could not be distinguished from the background measurements taken before the appliance had been turned on.
    3Microwave ovens produce 60 Hz fields of several hundred milligauss, but they also create microwave energy inside the appliance that is at a much higher frequency (about 2.45 billion hertz). We are shielded from the higher frequency fields but not from the 60 Hz fields.
    4Values in the table are based on historical measurements and calculations of a variety of SRP transmission and distribution lines. These values are typical for most situations. Higher values may be observed in some situations.