How is electricity delivered to our homes?

This is how I work for an electric utility.

All of it starts at the generating station. This is a coal-fired generator. Generators produce electric at 13.8 million volts (13.8kv). The power is then sent out of the building to a transformer, which increases the voltage to 138 000 volts (138kv). The power is then sent to a substation, where it is distributed over multiple lines to other substations. Another transformer is used to increase the voltage to 345 million volts (345kv), for long distance transmission. Because you can use smaller wires to transmit long distances, higher voltages are preferred.

A large 345kv to 138kv transformer. I am standing next to it to give an idea of scale. I am 6′-2″ (188cm)

These substations have breakers that are similar to those in your home, but larger to protect the system from any problems. Every circuit going in or out of any substation will be protected by at least one breaker.

Here is a 345kv breaker. Just to the right is the stand that it will be mounted on. Perhaps I should have posed like a spokesmodel for these pictures.

The electric then leaves the substation at the generation station and travels along the wires at the speed of 138kv. It then enters another substation, where it is taken into a transformer. There it is stepped to 69kv and divided into several circuits.

Here is a smaller 69kv to 12.5kv transformer. Yes, I’m aware that I’m dressed like a slob. They don’t pay me to be pretty.

It will either travel to another substation or to another location if it follows one of the 69kv loops. We will assume it travels to another substation. It is then taken to another transformer, which reduces the voltage to 12.5kv. The voltage is then sent through a switch gear equipped with breakers, where it is split into more circuits.

This is a 69kv breaker. The legs it would be mounted on are laying across the bottom. Next time I’ll hire a model to pose for these shots. Jeez, you people are so critical.

These 12.5kv circuits are then sent out to power a neighborhood. It will then travel to small transformers, which are either attached to a pole with overhead wires, or on the ground if underground wires are used. These small transformers can feed multiple homes and reduce the voltage to two legs each with 120 volts for a total of 244 volts. This voltage is fed into your home via the circuit breaker panel or other breakers, and distributed throughout your house.

Here is a switchgear, used to send the power out to your neighborhoods. This is the last picture of me you will have to endure.

It’s there. This is a quick guide on how electricity gets to your home. However, I’ve left out many details that wouldn’t be necessary to make this post longer. Most people won’t care. The system has a lot redundancy to ensure that it runs smoothly in case of problems. Protection and other purposes are covered by a lot of technology. The American electric grid, taken together, is the most complex machine ever built by mankind. The electric utility has been my employer for 10 years. I am still amazed at the work it takes to keep the lights on.


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