Why is my Generac Generator Running When Power is on

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Do you own a Generac generator that runs even when the power is on? In this article, we’ll explore the reasons behind this behavior straightforwardly. So, if you’ve ever asked, “Why is my Generac Generator Running When Power is on?” – Let’s demystify this conundrum.

A Quick Overview of Generac Generators

Let’s first understand how Generac generators operate before we delve into the reasons behind your generator’s unexpected behavior.

Generac generators have gained a reputation for their dependable performance and convenient automatic power-switching features.

When a power outage occurs, they immediately activate to keep your home or business running even when the grid is down. But what happens when your Generac generator decides to start when it shouldn’t? Let’s find out.

Common Reasons for Running Generator When Power is On

Now, let’s look at the common reasons why your Generac generator might be running even when the main power is on.

1. Automatic Transfer Switch (ATS) Issue

Automatic transfer switch for generac generator

Ensuring uninterrupted power supply during outages is the responsibility of ATS. The ATS is designed to detect any issues or failures with the utility power and signal the generator to start.

Once the generator runs smoothly and produces stable power, the ATS quickly and seamlessly transfers the load from the utility power to the generator. This transfer is crucial to maintain power in your home or business without interruption. Let’s check the possible issues with ATS.

Utility Breaker Tripped:

Issue: If the utility breaker connected to the ATS trips, the ATS may lose connection with the utility power supply and act as if the power is out.

Solution: Check the breaker panel for any tripped breakers and reset as needed. This is a simple yet crucial step to ensure proper power supply to the ATS.

Loose Connections:

Issue: Loose electrical connections can lead to a situation where the Automatic Transfer Switch (ATS) fails to detect and transfer power sources accurately.

Solution: Inspect the ATS for loose wires or terminals and ensure they are tightly connected to maintain reliable operation.

Moisture, Flooding, and Water Leaking on ATS:

Issue: Moisture, flooding, or water leaks can cause electrical issues and short circuits in the ATS.

Solution: To ensure the proper functioning of the ATS, it is essential to protect it from moisture. The ATS should be stored in a dry location, away from any sources of water leaks. Inspect the area surrounding the ATS for any signs of moisture and address them immediately. In case the ATS has been exposed to moisture, it is recommended to have it thoroughly inspected and repaired by a professional.

Damaged or Faulty ATS Controller:

Issue: A damaged or faulty controller in the ATS can cause incorrect detection and transfer of power sources.

Solution: If the controller is suspected to be damaged or faulty, it may need to be repaired or replaced. Consult with a technician or the manufacturer for a proper diagnosis and solution.

Dust and Dirt on ATS:

Issue: Accumulated dust and dirt can impede the proper functioning of the ATS by clogging components and affecting electrical connections.

Solution: It is essential to regularly clean the ATS to prevent the buildup of dust and dirt. Inspect all components thoroughly, paying particular attention to the contacts, to ensure they are free from debris.

2. Incorrect Wiring or Configuration

incorrect wirring can also cause to run generator while power in on
incorrect wiring can also be a cause!

Issue: If your Generac generator is running while the power is on, incorrect wiring may be the cause. This issue often arises when someone has recently worked on or tampered with the generator’s settings.

Solution: Your first step should be to check its wiring. Look for any cables that might have disconnected and reconnect them securely if you find any.

However, it’s important to note that working with electrical connections can be hazardous. It’s strongly recommended that you call a qualified technician.

Attempting to address wiring or configuration issues without the necessary knowledge can lead to accidents or further complications.

A professional technician can ensure the wiring and configuration are set correctly, preventing the generator from running when it shouldn’t.

3. Sensing or Control Panel Malfunction

Control Panel can also cause to run generator while grad power in one.

Sensing refers to the generator’s ability to detect the presence or absence of utility power. This capability is essential for determining when the generator should start and stop. When sensing is working correctly, the generator will kick into action during a power outage and shut down when power is restored. The sensing system relies on various sensors to monitor voltage, frequency, and other power parameters.

Issue: When the sensing system or control panel malfunctions, it can disrupt the generator’s ability to accurately detect the status of the utility power supply. This malfunction can result in the generator running when the power is on, leading to inconvenience, increased fuel consumption, and maintenance issues.


Inspect Sensing Components: Begin by examining the sensing components, such as voltage and frequency sensors. Ensure they are free from damage, corrosion, or loose connections. If any issues are detected, address them promptly.

Calibration and Configuration: Access the control panel to check and adjust the generator’s sensing and control settings. It may be necessary to recalibrate the sensors and adjust the threshold levels for power source detection.

Control Panel Testing: Test the control panel’s functionality to confirm that it is correctly interpreting the data from the sensing system. This will help identify any control panel malfunctions.

If you’re unable to diagnose or address the problem on your own, it’s advisable to enlist the services of a qualified technician with expertise in generator systems.

4. Power Fluctuations

fluctuation can also cause running generator

Issue: Brief power fluctuations or voltage spikes can trigger the generator to start unnecessarily. If the generator is overly sensitive, it may respond to minor power variations.

Solution: Adjust the sensitivity settings on the generator’s control panel. Reducing its sensitivity can help prevent false starts.

A technician can assist you in making these adjustments.

5. Maintenance or Firmware Updates

generator will also run while it update its firmwar

Issue: Generac generators may run briefly during maintenance or firmware updates to ensure they’re functioning correctly. This should be a temporary situation.

Solution: If the generator runs during maintenance or updates, it should return to normal operation once the updates are completed. This is usually not a cause for concern, as long as it’s temporary.

6. Battery Issues

low charged battery can also cause running of generator.

Issue: If your generator uses a battery, a weak or faulty battery may cause the generator to run at times when it shouldn’t.

Solution: Check the battery’s health and replace it if necessary. A healthy battery is crucial for the generator to start reliably when needed.

Read Beast Best Battery for Your Generac 22kW Generator if you need one.

7. Fuel System Issue

Issue: A problem in the generator’s fuel system can also cause it to run when power is on. This might include fuel leaks, clogs, or improper fuel supply.

Solution: Inspect the fuel system for any issues, such as leaks or clogs, and address them accordingly. A well-functioning fuel system is essential for the generator’s operation.

Why It’s Important to Address the Issue?

why we need to solve all these problems.

Addressing the issue of a running Generac generator when power is on is crucial for several reasons:

Fuel Consumption: Running your generator unnecessarily can result in increased fuel consumption, which can be costly over time. It’s important to conserve fuel resources.

Maintenance Costs: Unnecessary running of the generator can lead to increased wear and tear, resulting in higher maintenance and repair costs.

Environmental Impact: Increased fuel consumption and emissions can have a negative impact on the environment. Addressing the issue helps reduce your carbon footprint.

Noise and Disturbance: Generators can be noisy, and if they run when not needed, it can be a source of disturbance to you and your neighbors.

Reliability: You want your generator to be reliable during actual power outages. Ensuring it operates correctly when needed is essential for peace of mind.


To effectively resolve the issue of a Generac generator running when power is on, it is strongly recommended to seek the assistance of a qualified generator expert.

Attempting to troubleshoot and rectify generator-related malfunctions without the requisite knowledge and experience can lead to further complications and potentially exacerbate the problem.

Generator systems are intricate and involve electrical components, fuel systems, and sensitive control mechanisms.

Relying on the expertise of a professional ensures that the issue is accurately diagnosed, and the appropriate repairs or adjustments are made.

This not only prevents unnecessary inconvenience but also mitigates the risk of causing more significant problems with the generator.

When it comes to generator issues, calling in a knowledgeable expert is the surest path to a prompt and effective solution.


How long does a generator run after the power comes back on?

The duration a generator runs after power is restored depends on the type of generator, whether it has an Automatic Transfer Switch (ATS), and its settings, but it’s typically a few seconds to a few minutes.

Do I need to turn off the main breaker when running the generator?

Yes, it is generally recommended to turn off the main breaker when running a generator to prevent backfeeding and ensure safety during power outages.

Why a generator won’t stop running?

A generator may not stop running due to issues such as faulty ATS, improper wiring, stuck governor, fuel supply problems, control panel or sensor issues, programming errors, or battery/starter motor problems.

How do I turn off my Generac generator while running?

To turn off a Generac generator while running, locate the “Off” or “Stop” button or switch on the control panel and activate it

What is the main reason for Generator Running When Power is on?

The main reason for a generator running when power is on is often a malfunction or misconfiguration of the Automatic Transfer Switch (ATS) or the generator’s control system, which fails to recognize and switch to utility power when it’s restored.

Does the generator go off when power is restored?

Yes, if an Automatic Transfer Switch (ATS) is working properly; otherwise, manual intervention may be needed to turn off the generator when power is restored.

Sara Johnson
Sara Johnson

Sara Johnson founded whatgenerators.com, empowering individuals and businesses to utilize generators effectively. She simplifies complex concepts to create a more knowledgeable community in electrical power generation.

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