Can the voltage of an automatic transfer switch be changed?

Environment

Generac home standby generator systems that use an automatic transfer switch (ATS). This information is most helpful when an ATS appears to be rated for a different voltage or phase than the electrical service at the site.

Answer

No. An ATS does not have a setting that lets you change its supported voltage or phase. The voltage and phase an ATS supports are part of the switch’s design and rating.

Note: If an ATS voltage or phase rating does not match the site’s electrical service, the solution is selecting and installing the correct ATS for the application. Do not attempt to “convert” an ATS to a different supported voltage.

What “changing ATS voltage” usually means

Customers and installers often use the word “voltage” to describe different issues. Knowing which one applies helps identify the right solution.

• The ATS rating does not match the site’s service. For example, the site may be 120/208 three-phase, but the ATS is intended for 120/240 single-phase. In this situation, the ATS should be replaced with a model that matches the site requirements.
• The system transfers during low utility voltage events. Some customers want the system to be less sensitive to brief voltage dips. This is typically related to pickup and dropout voltage thresholds on supported standby generator systems, not changing the ATS’s supported voltage or phase.

How to avoid buying the wrong ATS

The best solution is selecting the correct ATS from the start. An ATS must match the site and the generator application, including voltage and whether the electrical service is single-phase or three-phase.

Before purchasing or installing equipment, Generac recommends working with an Independent Authorized Service Dealer (IASD) or a qualified electrician to confirm:

• The site’s utility configuration (voltage and phase).
• Generator compatibility with the site’s voltage and phase requirements.
• The correct ATS model and rating for the installation.

To find an IASD in your area, use the dealer locator.

If the goal is to adjust transfer sensitivity during voltage dips

If the ATS and site voltage and phase match, but the system starts or transfers during brief utility fluctuations, pickup and dropout voltage settings may be adjustable on supported standby generator systems. These settings should be evaluated and adjusted by a Generac authorized independent service dealer.

For more information, see Can the pickup and dropout voltage for a standby generator be adjusted?.

See also

• Automatic transfer switch compatibility guide
• What phases and voltage options does Generac offer for liquid-cooled automatic standby generators?
• How do I find a spec sheet for my transfer switch?
• Product lookup page