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. 

Safely transferring power using a portable generator and manual transfer switch

Disclaimer: This article provides general procedural guidance. Always follow local electrical codes and manufacturer instructions. Installation and maintenance must be performed by a Generac authorized service dealer or qualified electrician. Failure to follow safety instructions can result in death, serious injury, or property damage.

Introduction

A manual transfer switch allows you to safely connect a portable generator to your home or business during a power outage. The switch isolates the generator from the utility grid, preventing dangerous backfeeding and ensuring reliable power transfer. Generac offers several types of manual transfer switches, including the HomeLink™ manual transfer switch system and other standard models, designed for single-phase residential applications.

Environment

This procedure applies to:

• Generac HomeLink™ manual transfer switches (indoor/outdoor use)
• Generac manual transfer switches for portable generators (Models 6335, 6382, and similar)
• Generac power inlet boxes (30A or 50A, 125/250V) used to connect the generator via power cord

These switches are suitable for 120/240V single-phase systems and can be configured for various load center setups. Always confirm compatibility using the product lookup page.

Note: Manual transfer switches can only be used with portable generators, not home standby generators. A manual transfer switch does not possess the control wiring required to work with a home standby generator. Home standby generators are designed to be used exclusively with an Automatic Transfer Switch and are equipped with the appropriate control wiring to ensure compatibility: Can I Use a Manual Transfer Switch With My Home Standby Generator?

Safety

• Only Generac authorized service dealers or qualified service personnel should install or service manual transfer switches and power inlet boxes.
• Never connect a generator directly to a building’s wiring without a transfer switch—doing so can cause backfeeding, electrocution, or equipment damage.
• Operate the generator outdoors only, at least 5 feet from any structure, doors, windows, or vents to avoid dangerous carbon monoxide poisoning.
• Inspect cords, plugs, and switch enclosures regularly for damage or corrosion.
• Verify the portable generator, manual transfer switch, power inlet box, and power cord being used are rated appropriately for the intended use.

How do I know what manual transfer switch I have?

 

• Manual transfer switch model numbers, serial numbers, and rating information can be found on the identification label located on the device. Common model series include Generac HomeLink™ manual transfer switches.
•  Additional manual transfer switch models can be found here.
• If the label is unreadable or cannot be found, reference your original purchase documentation or use the product lookup page to identify your switch by serial/model number.

What is a power inlet box?

A power inlet box (sometimes called a generator inlet box) is the device that provides a safe, code-compliant way to connect your generator to your home’s electrical system. Some manual transfer switches incorporate a built in power inlet, while others require the installation of a separate power inlet box, which feeds power into the manual transfer switch, and then to the main electrical panel. Here’s a breakdown: 

Purpose

• The power inlet box acts as a dedicated entry point for electricity from your portable generator into your home.
• It prevents the need for running extension cords into your house, which can be unsafe and violate electrical codes.
• It works in conjunction with a manual transfer switch to safely switch between utility power and generator power.

How it works

1. The generator outputs power via its own cord (usually a heavy-duty extension cord).
2. That cord plugs into the power inlet box, which is mounted on the exterior of your house.
3. Inside, the manual transfer switch is connected to the inlet box.
4. When you flip the transfer switch, power from the generator is routed safely to the selected circuits in your home.

Key features

• Weatherproof enclosure for outdoor installation.
• Circuit breaker or fuse protection in some models.
• Rated for the generator’s voltage and amperage (commonly 30A or 50A).

 

In short: the power inlet box is the link between your portable generator and your home’s electrical circuits, making the connection safe, convenient, and code-compliant.

Performing a manual power transfer

IMPORTANT: the process described below is generally applicable to most portable generators and manual transfer switch systems. Always reference the owner's manual for your portable generator, manual transfer switch, and power inlet box (if applicable) to confirm compatibility and the manufacturer's recommended operational sequence for your specific products.

Transferring from utility power to generator power

1. Move generator outdoors. Be sure your generator is located at least 5 feet from windows, doors, or other openings to prevent dangerous carbon monoxide fumes from entering your home.
   
   
   
   
2. At the home's main electrical panel, turn off or disconnect all heavy-load appliances (like A/C units or sump pumps) in your home.
3. Ensure the manual transfer switch handle or switch is in the UTILITY position.
4. Outside, connect the generator power cord to the power inlet box and to the generator’s outlet receptacle.
5. Start the generator outdoors, following the instructions provided in its owner's manual.
6. Allow the generator to warm up for 1–2 minutes.
7. Move the transfer switch handle from UTILITY to GEN (generator). The mechanical interlock prevents both sources from being on simultaneously.
8. Turn on essential circuits in the transfer switch and the main load center up to the continuous wattage rating of your generator. If the generator main breaker trips, you have overloaded the generator. Some circuit breakers must be turned OFF to avoid damage to the generator or loads being connected.

Transferring from generator power to utility power

1. When utility power returns, verify stability by checking household lighting or a voltage meter.
2. Move the transfer switch handle from GEN to UTILITY.
3. Turn off the generator and allow it to cool before disconnecting the power cord.
4. Store the cord in a dry area, and inspect the system for any signs of overheating or damage before the next use.

Troubleshooting steps

1. Check the generator breaker

   • Confirm if the breaker on the generator is turned on, as this is often missed.

2. Verify the main breaker for the twist-and-lock plug

   • Ensure the breaker that serves as the generator “main” breaker is engaged.

3. Move the toggle switch on the MTS (Manual Transfer Switch)

   • Switch it to the generator position.

4. Confirm all breakers are turned on

   • Make sure the breakers in the system are not left off, as that will result in no power.

Additional resources

• What is a Manual Transfer Switch?
• Can I Use a Manual Transfer Switch With My Home Standby Generator?
• Why you should never back-feed your electric panel with a generator
• Locate an authorized Generac dealer