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?

You pretty much have to trust to their design and Quality operations, but
.... if it has UL, CSA, EU or other comparable safety markings (which are
required in order to sell them), you can pretty much assume they'll do the
job they're designed for.

Do NOT short the leads to "test" a breaker! You may or may not have a
functionally, to-spec breaker after that! Just in case the idea sounded
good to you g.

Pop`