Electric Transmission Lines is a polyline theme representing electric power lines of transmission and sub-transmission voltages covering North America.
Transmission lines can carry alternating current or direct current with voltages typically ranging from 110 kilovolts (kV) to 765 kV. Transmission lines can be overhead and underground; underground transmission lines are more often found in urban areas. Sub-transmission lines generally carry voltages ranging from 33 kV to 100kV. These sub-transmission lines transmit power from higher voltage lines or other bulk power sources to local distribution network substations.