Firman Load Starting Surge / Breaker Trip

Generator runs but trips its main breaker or house breakers when large loads start (e.g., air conditioner).

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Load exceeds generator surge capacity, Weak main breaker, Motor loads starting simultaneously, Loose connections causing heat and nuisance trips

How to Fix / Troubleshooting

Safety first: Turn OFF the generator and ATS before working on breakers or wiring.

  • Stagger load starts: Configure high-surge loads (HVAC, pumps) to start at different times or use load-shedding controls if available.
  • Check breaker rating: Confirm the Firman generator main breaker rating matches the generator's kW rating and has not been downgraded.
  • Inspect connections: Tighten all lugs at the generator main breaker and ATS. Overheated connections can weaken breakers.
  • Replace weak breaker: If the main breaker trips at currents below its rating, replace it with an OEM-equivalent breaker.

If your standby generator is undersized for your home's starting loads, consult an electrician about load management or upgrading capacity.

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Repair Difficulty

Medium 3/5

Required Part

Generator Main Breaker
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