What causes generator overload?

• Generator overload is caused when the electrical load demand meets or exceeds the power rating of a generator. For example, if a 24kW generator has 25kW of electrical load demand being placed on it.
• Generac generators are equipped with overload protection. In the rare event of an overload, the generator’s main line circuit breaker (MLCB) will trip, disconnecting the unit from the load.
• To learn more about the MLCB, see here: What is the generator main line circuit breaker? (MLCB).
• The most common method to resolve an overloaded generator is to disconnect or turn off large electrical loads.

 

Environment

This article focuses on overloaded home standby generators. However, the steps to resolve an overloaded portable generator are similar: Why Does My Portable Generator Keep Shutting Down?

 

Overload conditions

• Most Generac home standby generators produce 60Hz, or 3600 rpm. This is the frequency produced by the engine's speed to generate electricity.
• All generators have a data tag which provides information on the voltage and current rating. If the generator's electrical load approaches or exceeds this rating, it may be overloaded.
• When a generator is overloaded, it's RPMs will drop, and so will its frequency.
• An overload condition will activate a load manager (if in use) and/or the SACM in the transfer switch. These devices manage the electrical circuits the generator is supporting to reduce the risk of a shutdown due to overload.
• If the load demand being placed on the generator is 80% of the generators power capacity (or rating), the risk of overload is present.
• If low frequency is detected, or if frequency remains low for a period of time, the generator may shut down with an error.
• Symptoms of an overloaded generator include dimming lights, error codes on the control panel, or a complete loss of generator power.
  
  

Error codes related to generator overloads

Overloading may cause these error codes to display on the control panel:

• What Does It Mean When My Generator Displays an Error Code: Overload, Code 2100?
• What does it mean when my generator displays an alarm: Overload Remove Load, error codes 2100-2103
• What Does It Mean When My Generator Displays an Error Code: Underspeed, Code 1600
  
  

Troubleshooting overloads

To troubleshoot an overloaded generator, we recommend:

1. Disable large, nonessential electrical loads by switching off their associated breaker in the home's electrical panel.
2. Check the generator's main line circuit breaker (MLCB). If it's set to OFF, switch it to ON.
3. Then, on the control panel, clear the error code by pressing OFF then ENTER.
4. Set the generator back to AUTO mode and try running it again. The generator will power on if utility power is absent.

If the overload error continues to happen, remove additional electrical loads. If this does not resolve the issue, contact a Generac authorized service dealer.