This booklet uses six basic electrical terms- conductor, current, voltage, load, power, and circuit. Current is the movement of electrons in the conductor. Voltage is the electric force that causes current in a conductor. Load is the electric power needed by homes and businesses. When a conductor energized with voltage is connected to a load, a circuit is completed, and current will flow.
Transmission lines are high-voltage power lines.
The high voltage allows electric power to be carried efficiently over long distances from electrical generation facilities to substations near urban areas. Electrical substations serve many functions in controlling and transferring power on an electrical system. Several different types of equipment may be present, depending on the functions of the particular substation. For example, transformers change the high voltages used by transmission lines to the lower voltages used by distribution lines. Circuit breakers are used to turn lines on and off.