Just a little anecdotal experience. I have a 230a "buzz box" that said it should be on a 48a breaker (unobtanium). Since I didn't have any easy way to put in another circuit when I bought it about 37 years ago I just put a dryer plug on it and plugged it into the 30a circuit my dryer was on. It has never blown a fuse or tripped a breaker and I still run it on 30a circuits.
I may have never used it on the highest setting with the biggest rod it will handle, using it at the maximum duty cycle but I doubt anyone else does either.
