Why Does an RTU Trip the Breaker When Starting?
If a rooftop unit trips the breaker immediately upon startup, the most common cause is excessive inrush current from the compressor or fan motor.
Common Causes
- Shorted compressor windings
- Failed start capacitor
- Locked rotor condition
- Undersized breaker
- Ground fault
- Loose electrical connections
Troubleshooting Steps
- Measure compressor winding resistance
- Inspect start and run capacitors
- Check breaker rating versus unit specifications
- Inspect wiring for signs of burning or insulation damage
Repeated breaker trips require immediate diagnosis.
FAQ
Is this dangerous?
Yes. Repeated breaker trips indicate a serious electrical issue.