QO Circuit Breaker buzzing under load
I have a 200 amp Square D panel with QO breakers. Due to a kitchen renovation I am using my basement workbench as a temporary kitchen area. The workbench has a 20 amp circuit with two double receptacles. The 12/2 wiring and receptacles are only about 6 months old, but I don't know the age of the breaker in the panel. The wiring only goes across the basement about 25 feet, and there is nothing else on this circuit but the two workbench receptacles.
This morning the drip coffee maker was plugged in to one receptacle ( I don't know what the coffee maker draws after it stops perking.) and I plugged a 1500 watt hot plate into the 2nd receptacle and turned it on. I was close enough to the panel to hear the breaker start humming under load, and it then stopped after about 15-20 seconds.
Does this mean I have a breaker that may fail in the near future, or does the humming just mean I'm near the max amperage on the breaker? I think this breaker is an old one they reinstalled during the heavy-up, so I don't know its age.