How Does a Whole House Backup Generator Work?

By Lyle Weischwill | Apr. 29, 2022 12:08 pm PST

When your home loses its primary source of electrical power due to a utility company power outage, a whole house backup generator kicks in to supply your home with electricity.

Here’s how it works.

Fuel Supply

The backup generator needs a fuel supply to start and run the engine during an electric power outage.

Many homes have a dependable supply of natural gas even when electrical power goes out. A whole house generator will typically use that natural gas supply to start and run the engine. Homes that use a Propane tank to supply the house with gas will use the LP gas supply from the Propane tank to power the generator. All-electric homes will typically need to have a Propane tank installed to provide the backup generator with fuel.

The home generator installer will hook up the fuel supply to your backup generator.

Generator Engine

Next, the standby home generator needs a powerful and dependable engine to spin the rotor shaft to generate electricity.

A battery-powered starter motor turns the engine over and the engine starts and runs to rotate the generator rotor shaft.


The generator rotor shaft spins the armature core inside a magnetic field inside the generator to convert the mechanical energy of the spinning shaft into electrical energy supplied to your house.

Generator Controller

When the transfer switch detects a utility power outage, it sends a signal to the generator controller. Next, the generator controller starts the engine and gets the generator ready to supply your home with backup power. The controller then signals the transfer switch to connect generator power to your home’s electrical system.

Generator controllers on many whole house standby generators also perform these functions:

  • Periodically runs the generator in an exercise cycle to lubricate the engine and maintain engine seals.
  • Monitors engine and generator performance and detects problems.
  • Communicates problems through the remote monitoring and access system through text alerts and emails.
  • Schedules regular preventative maintenance through your service provider.
  • Allows you to manually and remotely change controller settings.

Permanent Wiring and Transfer Switch

The permanent wiring connects the generator output to the automatic transfer switch. The transfer switch monitors primary utility power and sends a signal to the generator controller when it detects a utility power failure. The transfer switch then connects backup generator power to your home’s electrical system when the switch receives the transfer signal from the generator controller.

The transfer switch also restores utility company power when it becomes available and sends a signal to the generator controller to shut off the backup generator.

Installing a whole house standby generator gives you the peace of mind that your home won’t lose power during a utility company power outage. With this automatic backup generator system, you can maintain normalcy in your home when your primary power supply goes out.

Schedule an appointment with a home generator consultant today to begin installing a whole house backup generator for your home.

Get a free in-home consultation

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