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A Masterpact NW or Powerpact P or R frame circuit breaker has gotten wet and is nuisance tripping; what should be done?

FA177865

23 January 2021

Issue:
Water damaged Masterpact and Powerpact breakers

Product Line:
Circuit Breakers

Resolution:
Masterpact and Powerpact P and R breakers which have gotten wet are prone to nuisance tripping. Water will interfere with normal operation of the current sensors, reporting more current to the trip unit than actually exists, resulting in tripping with Ir, Ii, Ig, Ap indication, or no indication. Which function trips depends on the magnitude of phantom current reported to the trip unit. 
It is also possible for water to compromise the trip unit as well, also causing nuisance tripping.
Once a circuit breaker has become wet enough to nuisance trip, it cannot be restored to reliable operation and the recommendation is to replace the breaker.