Read the manual thoroughly and understand all of the instructions, cautions, and warnings before using this equipment. If any section of the manual is not understood, contact your nearest authorized dealer, or contact Generac Customer Service at 1-888-436-3722 (1-888-GENERAC), or www.generac.com with any questions or concerns. 

Understanding N1 and N2 control wires

Environment

This information applies to Generac air‑cooled standby generators equipped with an automatic transfer switch (ATS) that uses N1 and N2 control wiring for utility power sensing.

Overview of N1 and N2 control wires

The N1 and N2 control wires are responsible for detecting the presence, loss, and restoration of utility power. These wires provide a low‑voltage sensing signal between the transfer switch and the generator controller.

When a voltage drop below a specified threshold—or complete loss of utility power—is detected on the N1 and N2 connections, the generator automatically starts and prepares to supply backup power. Once stable utility power is restored and detected through these same control wires, the generator will shut down after the programmed cool‑down period, and power will be transferred back to utility.

Control wire identification

• In the image below, the control wires (including N1 and N2) are highlighted in red to indicate their location and routing between the transfer switch and the generator.
• The wires in blue (also labeled as N1 and N2) are the main utility power conductors entering the transfer switch from the utility supply.
• The blue N1 and N2 utility conductors are separate from the red N1 and N2 control wires.

Note: The image below is for reference purposes only. Wiring configurations may differ depending on your ATS model. Refer to the owner’s manual or installation manual for the recommended wiring for your application.

Safety notice: N1 and N2 control wiring should only be installed, inspected, or serviced by a Generac Independent Authorized Service Dealer (IASD) or a qualified electrician. Improper wiring can prevent the generator from responding correctly to utility power conditions.