Overload or Nuisance Tripping
The generator trips, and the question that decides everything else is simple: was the load actually too much for it, or did it trip on something it should have handled easily? The first is the generator doing its job correctly. The second means something else is wrong.
What this looks like
A real overload trip happens under identifiable circumstances — a well pump, central AC compressor, or air compressor kicking on and spiking current well beyond the generator's steady rating, or too many circuits transferred at once on a system without load management. It's reproducible: run the same combination of loads again and it trips again. Nuisance tripping looks different — the generator cuts out under a load that's clearly within its rated capacity, sometimes with no obvious pattern, sometimes tied to a specific circuit rather than total demand. Generac's Evolution/Nexus controller reports a genuine overload as code 2100 and a load-related voltage sag as 1900 (Undervoltage). Kohler's RDC2/DC2 shows the equivalent as Voltage Low, and on some units, EngineSpeed Low if the engine itself bogs down under the load. Briggs & Stratton's Home Generator System blinks its LED three times for FC_3 (Low Voltage) or five times for FC_5 (Low Frequency), both of which its own documentation ties directly to overload conditions.
Most likely causes, ranked
- Genuine overload from simultaneous large loads. Multiple high-draw circuits transferring at once, especially without a managed or load-shed transfer switch configured for the home's actual demand — the single most common real cause.
- Large motor starting under load. Well pumps, central AC, and air compressors all draw several times their running current for a fraction of a second at startup, which can trip a generator that would handle their steady-state draw without issue.
- Short circuit or ground fault on a connected branch circuit. This is where "nuisance" tripping often turns out not to be nuisance at all — a real short can look exactly like an overload trip from the generator's perspective.
- Managed transfer switch load-shed settings misconfigured. If the switch is supposed to manage which circuits get power and doesn't match the home's real demand, it can allow combinations of loads through that the generator can't actually support.
- Failing voltage regulator or worn alternator components. Less common, but a regulator or stator issue can make the generator trip on loads it used to handle fine, with no change in the house's actual demand.
Which fault codes match this
| Brand | Code / display | What it points to |
|---|---|---|
| Generac | 2100 (Overload) | Current draw beyond rated capacity, or blocked restart under load |
| Generac | 1900 (Undervoltage) | Output voltage sagged below ~80% of rated, often from overload |
| Kohler | Voltage Low | Output below ~80% of nominal, most often overload or a failing regulator |
| Kohler | EngineSpeed Low | Engine bogging down under load, dropping below ~85% of normal speed |
| Briggs & Stratton | FC_3 | Output voltage out of range, tied to fuel restriction, wiring, or overload |
| Briggs & Stratton | FC_5 | Frequency below ~55 Hz for 3+ seconds, most often from overload |
What you can check yourself
- Note exactly what was running when it tripped — this is the single fastest way to tell a real overload from something else.
- Manually shed some circuits at the transfer switch or main panel before clearing the fault and retrying.
- Stagger large appliances instead of starting them at the same time if you're managing load manually.
- With the unit off and battery disconnected, check for obviously loose lugs or scorched wiring at the generator's output connections.
- If a managed transfer switch is installed, confirm its load-shed configuration actually matches your home's real circuits and demand.
- Clear the fault and retest with a deliberately lighter, known-safe load to see whether the trip point has changed.
More help
Already staring at a specific code? Try the code lookup. Otherwise see the full brand lists: Generac, Kohler, or Briggs & Stratton.