Automatic transfer switches

An Automatic Transfer Switch (ATS) is an electrical switch that automatically transfers power from the primary source (utility power) to a secondary source (backup generator) when the generator's controller senses a power outage or interruption in the primary source.

 

Automatic transfer switches are used in home standby generator systems to ensure continuous power supply to critical loads in buildings, hospitals, data centers, and other facilities. Together, the generator's controller and the ATS monitor the power supply and automatically switch between the primary and secondary sources, allowing for uninterrupted power supply.

 

Automatic transfer switch facts

• All residential and commercial-rated transfer switches are open transition switches (there is no overlap when power is handed off from utility to the backup generator).

  • The switch must break a connection with one source of power before making a connection with the other. This eliminates the possibility of back-feeding.

• A transfer switch is required by NEC for any connection of power to a home.

• Automatic transfer switches can be either service-entrance rated, or non-service-entrance rated. To learn more about each, see here: What's the Difference Between A Service-Entrance Rated and Non Service-Entrance Rated Transfer Switch?

• For use with automatic home standby generators ONLY.

  • Portable generators do not have circuitry to control an ATS.

• Permanently installed and hardwired.

  • Can be rated for indoor or outdoor installations.

• Can be purchased separately or may come bundled with the generator.

  • Note: Liquid-cooled generators are not available as a bundle, the switch will need to be purchased separately.