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What is a Home Standby Generator’s Automatic Transfer Switch?

As more and more homeowners around the Denver-Boulder metro area look into having a home standby generator installed, our electrical team at Save Home Heat Company will continue posting about different aspects of these automatic, backup electrical power sources. In this post, we’ll present an overview of an important component in the system, and which is required by National Electrical Code (NEC). We’re talking about the Automatic Transfer Switch, commonly known in the electrical field as an ATS.

The ATS plays a crucial role in making sure that systems such as heating, cooling, refrigerator/freezer, well and sump pumps, and other priority circuits in your home will receive backup power from your standby generator in the event of a power outage.

The Role of an Automatic Transfer Switch

The ATS is the component in a whole-home standby generator system that continuously monitors incoming power from the utility grid to your home, and coordinates generator operation, as needed. If there’s a power outage from the grid, the ATS quickly senses the loss of power and automatically switches the power source over to the generator, while signaling the generator to turn on.

The ATS is the electrical device responsible for directing either incoming power from the utility grid or backup power from the generator to the home. In other words, the ATS continuously monitors electrical power supply conditions to your home, and decides and coordinates which power source will be providing electricity to the home. This process includes switching from the generator back to incoming utility grid power when electricity to the home is restored, signaling the generator to shut down when normal conditions have been restored. Power from the utility grid and the generator both flow thru the ATS to the house.

What’s Inside an ATS?

The components inside an automatic transfer switch typically consist of a solid state control module that works in concert with internal switching devices such as contactors, relays, and circuit breaker switches; of course, there’s also appropriate wiring. Inside the ATS is where incoming power from the grid is continuously monitored. As alluded to above, the ATS is the critical meeting point of backup generator power, main grid power, and the home’s electrical system.

Matching an ATS with the Home’s Electrical System and Generator

The specific model of automatic transfer switch employed for a standby generator installation is determined to a large extent by the rating of the electrical service provided to the home from the local utility (Xcel Energy for many of us in the Denver-Boulder area). Without getting too technical, the electrical service that many homes in our area receive is rated between 100 amps and 200 amps, depending on the home.

Similar to other components in the home’s system, the ATS, including its main breaker switch and internal components, is sized to safely accommodate and route the maximum amount of electrical power that the grid normally supplies to the home. This power is parsed out to the individual electrical circuits thru the home’s electrical service panel and its individual circuit breaker switches. The generator circuit inside the ATS has its own breaker switch, as well.

Professionally Preparing Your Denver-Boulder Home for a Power Outage

While the prevailing hope is that you will rarely have need of a standby generator for your home in the Boulder-Denver metro area, these days more than ever, it seems that’s not a given. Our electrical team at Save Home Heat is currently installing more home backup generators than ever before.

Please contact me to schedule a standby generator install quote for my home!