A circuit breaker that trips when the compressor runs, or on start, indicates an overcurrent condition. The cause may be in the supply, the machine or the motor, and it must be found rather than bypassed.
Common causes
- Undersized wiring or breaker for the motor current
- Voltage drop from a long supply run
- Dirty intake filter or high ambient increasing motor load
- Failing capacitor or motor winding fault
- Mechanical binding in the airend or fan
Diagnosis
Check the running current against the motor nameplate and measure the supply voltage under load. A current reading well above the rating points to an overload, while a trip only at start suggests high inrush or a weak breaker.
Safety note
Never upsize a breaker to stop it tripping; the breaker is protecting the wiring and motor. Repair the actual fault, and have an electrician verify the supply and protection are correctly sized.