In article , bud-- wrote:

The line cords are designed to be safe to operate on a 20A ckt. That
means, for instance, that the conductors will survive the available
fault current for the time until a 20A breaker/fuse will open. That is
why you can have 18ga extension cords on a 20A ckt. I wouldn't bet that
is true on a 30A breaker, which may have a higher fault current or will
take a lot longer to trip at the same fault current.

You're obviously another one of those misguided souls who believes that
breakers are there to protect the stuff that's plugged in to the receptacles.

Repeat after me: Breakers are there to protect the branch circuit wiring.
Breakers are there to protect the branch circuit wiring. Breakers are there to
protect the branch circuit wiring. Breakers are there to protect the branch
circuit wiring.