Notice the big spark at the contacts. That spark causes carbon build up on the contacts, so the more often the breaker trips (or is used as a switch on heavy loads) the more the carbon builds on those contacts. This excessive build up can cause additional heat inside the breaker which in turn causes the breaker to trip prematurely. People usually refer to this as a "weak" breaker.
The bi-metal can also get "sprung" from excessive tripping and it takes less heat to reach it's tripping point also resulting in a "weak" breaker.
Cool video, I expected a larger arc on the direct short however.
Last Edit: Jan 24, 2018 9:26:09 GMT -5 by BeeAmaker
Some things are meant to be closed. Your mind isn't one of them.