Troubleshooting
Breaker trips under load
Separate overload, fault, connection, equipment, and coordination causes.
A delayed trip usually requires separating actual overload from heat, loose connections, equipment faults, harmonics, and incorrect protection.
Collect
- Trip timing, load profile, breaker type/rating, ambient temperature, conductor data, and recent changes.
Tests
- Inspect/torque only under appropriate de-energized procedures.
- Measure load and phase balance with a properly rated instrument.
- Use thermal inspection only within an approved energized-work program.
Interpret
- Compare measured current and duration to the breaker curve and equipment duty.
- Look for localized heat, harmonic loading, shared neutrals, and intermittent equipment faults.
Verify
- Correct the confirmed cause and repeat a representative load cycle; never upsize protection without revalidating the entire circuit.