High-voltage transmission lines form the backbone of electricity systems. Transmission lines are designed to carry large amounts of electricity at high voltages, typically 115 to 500 kilovolts (kV), across long distances. Networks of transmission lines transfer electricity from power plants or other interconnections to substations. At substations, the high-voltage electricity is “stepped down” to a lower voltage, which can be carried via lower-voltage distribution lines to residential, business, and governmental consumers.
The construction and operation of high-voltage transmission lines are regulated by a variety of state and federal agencies and regulations. In addition to electrical system regulations, transmission lines are subject to environmental laws and regulations at the state and federal levels. Local zoning regulations and land use plans may also govern the location of high-voltage transmission lines within counties and cities.