In many facilities, the breaker maintenance program consists of "replace when nuisance tripping becomes intolerable." Yet, nuisance tripping isn't the worst failure mode. It's far worse when the breaker just doesn't trip. This failure mode means you have no circuit protection.
Breakers fail in this "no trip" mode for a variety of reasons, all of which can be addressed in a way that nearly guarantees this mode will not occur. Among the causes:
- Dust accumulation.
- Grease absent, hardened, or contaminated.
- Fatigue of metal parts.
- Trip linkage is broken or out of adjustment.
- Dashpot leaked.