TRANSMISSION LINE FAQ   
  • How does electricity arrive at my home?
  • Electrical lines and facilities are a necessary part of the infrastructure within any community, just like roads, water and sewer facilities. Much like our highway system, Idaho Power and Rocky Mountain Power's power line grids are made up of high capacity transmission and low capacity distribution lines.

    The high capacity transmission lines operate somewhat like interstate highways and freeways that move a large volume of vehicle traffic. Electricity flows on this electric "freeway" to a substation, where it is reduced to a lower voltage and sent out again on distribution lines. The lower capacity distribution lines operate like streets and avenues that crisscross communities and neighborhoods. Many are needed to get from one destination to another.

  • What is a substation and why is it necessary?
  • A substation is used to transform one voltage to another and for protecting and controlling transmission and distribution lines.

    For efficiency, each company tries to minimize the electrical losses (inefficiencies) on the transmission system. The higher the electrical current, the higher the losses. Therefore, it is in the power company’s best interest to transmit power at the lowest current possible.

    To do this, the voltage must be as high as possible. Substations are used to raise voltages for long distance transmission and to lower transmission voltages for distribution to the end users. Without substations, generation would have to be located very close to the customer load.

  • Will the substation/transmission line attract lightning?
  • Substation structures and transmission lines may attract lightning; however, the shield wire (found along the top of the structures) provides protection to the system. Lightning that would hit the area will hit the line rather than a house or tree.

  • Will the lines make noise?
  • Audible noise (often referred to as “corona”) may be described as a sputtering sound or a low frequency humming sound. Irregularities on the surface of the conductor such as nicks, scratches, contamination, insects and water droplets can increase audible noise. Consequently, during periods of rain and foul weather, line noise may be more audible (although this may be masked by the sound of rain). Under most circumstances, line noise will typically be inaudible past the edge of the right of way during fair weather.

    To minimize noise levels, substation and transmission line materials are designed according to industry standards and the best possible construction techniques will be used to insure that hardware is tight and that the conductor surface is not scratched or nicked during construction.

  • Will the lines cause radio, television or cell phone interference?
  • Electromagnetic fields (EMF) do not cause radio, TV or cell phone interference. Modern line design has eliminated problems that caused noise or interference in the past. While it does happen occasionally, it is typically on older lines or where a piece of equipment is not operating correctly. When a problem does occur, the companies have the equipment and trained personnel to address the issue as required by the Federal Communications Commission (FCC).

    For more information about EMFs visit the Safety page.

  • What are the health effects of electromagnetic fields?
  • Since the early 1970s, extensive research has been performed to determine if EMFs pose health risks. Some studies have suggested a statistical association between EMF and certain diseases, while other studies have failed to show this relationship. Ongoing research into EMF has detected no cause-and-effect relationship between EMF and disease. While EMF can produce biological effects, it is still unclear whether these effects are of any consequence to human health.

    Idaho Power and Rocky Mountain Power agree with the overwhelming body of scientific research that shows EMF is not detrimental to human or animal health. Both Idaho Power and Rocky Mountain Power continue to stay up to date about EMF studies and are dedicated to addressing EMF concerns among its customers. We encourage you to learn more about EMFs by visiting:

    National Institute of Health’s EMF page

    EMFs - Electric and Magnetic Fields Associated with the Use of Electric Power: Questions and Answers (PDF) by the National Institute for Environmental Health Safety and the National Institutes of Health, June 2002.

    World Health Organization’s EMF page