OK, my mistake, it's a dryer cord, so all the conductors are 10 awg. So, I repeat, has anyone ever seen a floor sander that was over 5hp?
Can we assume that the floor sander contains running overload protective devices? I've never actually studied one that closely, but these things are manufactured by businesses that have to worry about product liability, and I assume their product is listed, so let's say yes.
That leaves branch-circuit short-circuit and ground-fault protection. Table 430.52 says that for an instantaneous-trip breaker (realistically the norm in any residence nowadays), the maximum percentage of full-load current is 800%. 800%*28A>50A. Did I do that right? Article 430 is probably the trickiest article in the NEC, I don't use it all that much, it's late on a Friday night, and I've had a few brews. Even if I'm wrong, I have to give credit to the floor sander guy for at least trying to get it right.
