- Power plants generate electricity and send it through a step-up transformer, which raises the voltage level and sends the electricity to transmission lines. Transmission lines are noticeable by the tall transmission towers that support them. Transmission lines carry high-voltage power to transmission substations.
- Transmission substations contain transformers that lower the voltage of electricity and distribute it between lower-voltage lines. A transmission substation can serve tens of thousands of customers.
- Distribution substations further lower the voltage of electricity and distribute the power to cities and towns through main lines, which serve hundreds of customers.
- Branch lines carry lower voltage power to clusters of homes and businesses, and are supported by wood poles.
- Service drop lines serve single customers. The voltage from a branch line is lowered through a transformer at the pole that connects to your home or business through the service drop line.