On 1 Dec 2006 09:31:58 -0800, "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?

Will the plug go in a 50A recpt? If it does then I see no reason to
change it.

You would only have to change the breaker if you changed the outlet.

I think most receptacles are keyed somehow to keep you from using an
incorrect appliance.

You can plug a 15A device in a 20 Amp recpt, but you can not plug a
20A plug into a 15A recpt.