BobH wrote:
I am changing a 50-amp breaker to a 30-amp one to install an oven that
draws less current than the old one did. I have seen information here
about testing a bad circuit breaker, but how do you test a good one? In
other words, if I install a new breaker, how do I know it will trip if
the load exceeds 30 amps?

Other than shorting both legs of the 220 line and creating an
impressive spark, you just assume, as the rest of us, that the breaker
works, and chances are that it will.

What is the current draw on your new oven at full load?