I got a Service call for a Main Breaker tripping in an Apartment Suite... When she said it hsppened when her appliances were all on, and even when she only had the Heater running one night I knew it was probably just a loose connection Cutler Hammer BR2100 Breaker. I removed part of slightly discolored aluminum strands, applied antioxidant and tightened all the screws. It's for a Property Management Company. I am thinking it would be best to change the Breaker after tripping at least twice that I had heard, since I was told by the Supplier the Manufacturers only warranty breakers for one trip? .. Seems they always work in old homes again and again, but to cover all cases I guess it would be wise to change it? Thanks again for any insight!
If you were lucky enough to be present when the breasker tripped if you attempted to latch it on reclose it were you able to latch it? If not the breaker most likely tripped on thermal where you would have to wait a bit for the thermal element to cool off before the breaker is capable of being latched and closed.
It you are able to latch the breaker shortly after the breaker tripped it most likely tripped on magnetic. If so it is never recommended to close a breaker back into a fault and must be investigated for a cause on trip and resdolved before there is an attempt to reset and close.
Persdonaslly I would opt that there is a thermal tripping issue which the others pointed out could be due to a termination issue which causes heating of the breaker which results in derating the breaker and a nuisance trip. Sinse the trip unit is close to the load end terminals I would explore the load side terminals to see if those connections have been compromised.
Since any heating at the line side terminals has to be conducted through the stationary and moving contacts is order to affect the thermal element there has to be a significant amount of heat generated to affect the thermal element. Your concern also should be abould the weakening of the contact springs whichnwoulkd cause a contact failure.
Of course should heating be as the result contact resistance itself there aslo should be a concern for weakening the contact spring(s) which escaslates the failure.
Often time using an infrared scan can be helpful in diagnosing the problem.