Reno, 240.4(B) says "Devices Rated 800 Amperes or Less." so the break is at 801 amps. (similar to language referring to 601 volts). I agree the difference is largely semantic since plus/minus 1 volt or 1 amp is well within the tolerance of the devices but they have to draw the line somewhere. I do agree with Tesla that you need engineering guidance when you get up into this big stuff.
