Sending power to your home is a lot like driving to a neighboring state.  You wouldn’t consider taking a two-lane secondary road to travel to a city hundreds of miles away, would you? Of course not: You would find the nearest interstate so you could drive faster and arrive at your destination in less time.
Just like you, your electricity has an interstate that allows it to travel long distances, and a secondary system that winds through back roads and neighborhoods to direct it to its final destination, your home.
Transmission lines that deliver power from a power plant to substations are the fast-moving interstate highways of the electric industry. These lines carry from 23,000 to161,000 volts of electricity into the local distribution substation. They are located on structures ranging from large metal towers more than 100 feet tall to a single pole standing 70 to 90 feet in the air.
And just like a car leaving the interstate, the electricity leaving the substation has to slow down when it enters the distribution lines serving southeast Iowa’s service area. Transformers in the substation provide the braking system for lowering the voltage of the electricity so it can continue safely along its journey.
So, how does it work? Higher voltage electricity passes through a system of coiled wires located in the substation transformer. The electricity enters a primary side of the transformer, which has metal coil windings surrounding that side of the transformer, and then passes to a secondary side, which has fewer coil windings. Travelling through the reduced number of windings lowers the voltage as it leaves the secondary side and continues the journey along the distribution lines.
The electricity moving along Access Energy Cooperative’s distribution lines are cruising between 7,200 volts to 12,470 volts, depending on whether or not they are travelling along a single-phase, two-phase or three-phase line. Consider these lines the secondary roads of the electric system. They make the journey through the local co-op’s service area.
Distribution lines carry the electricity shorter distances than transmission lines. They transport electricity to the businesses, schools and homes served by your co-op.
Your electricity has one more stop before making its way into your home. Just as you slow down to pull into your final destination, the voltage is lowered one more time. It takes a turn off the distribution line and into another transformer that’s located outside your home.
This transformer may be a canister hanging on a pole or a box in your yard if you have underground electric service. Like the substation transformer, the electricity passes through a primary side with more coil windings to a secondary side with fewer coils. The voltage leaving the secondary side is generally between 120 and 240 volts.
     After the electric current leaves the transformer, it makes its way through a service line, into the meter base and to its final destination – your home, where it powers the appliances and electronics of our modern world. As you can see, the electric highway plays a key role in powering our lives and delivering safe, reliable and affordable electricity to you.

Source: Karen Combs