October / 2001
The Future of Electricity

How electricity is distributed

Step 1
The electric transmission system ends and the distribution system begins at a substation. A substation is essentially a series of transformers surrounded by circuit breakers and other safety and protective devices. The substation transformers "step down" the voltage from high-power, long-distance transmission lines, by reducing it from as much as 765,000 volts to less than 39,000 volts. This makes the electricity easier and safer to handle.

Step 2
Distribution lines carry the electricity from the substation to transformers mounted on poles or in metal boxes on the ground for underground lines. These transformers further reduce the voltage, to the 120 or 240 volts used by most homes and businesses.

Step 3
Wires carry the electricity from the transformers to residential, commercial, and industrial customers.