Even a terrible engineer can't stretch the facts to imply that inrush current equates to HP, because the speed is essentially zero at that point, so the HP formula cannot work. HP does NOT relate directly to current, otherwise you could rate a transformer as having HP! Current relates to torque, and torque relates to HP, but the HP formula is Tq x RPM/5250, so if RPM is zero, everything else is zero. There is another explanation though.
In college in the '70s I worked for Sears selling bench power tools (table saws etc.) when they began using the marketing term "develops __HP". Being an inquisitive sort and an EE student at the time, I asked an Emerson rep one day what they meant by "develops" (Emerson was making all of the Sears brand tools at that time). He explained that they meant that when the load increased the slip to where it put the motor into Break Down Torque (BDT), the total HP could be "recalculated" at those values. Well on a Design B motor, BDT can be as high as 220% of FLT and even though speed would be lower in order to achieve that torque level, the total "recalculated" HP at that point came out to be higher than the "old" HP rating. For example, we had been selling a 1HP motor on the belt driven table saw one day, then the next shipment came in with the EXACT same motor and the literature said "develops 1-3/4HP". So at it's rated 1750RPM it was 1HP, which meant 3ft.lbs. of torque. That meant that BDT was 6.6ft.lbs. and occurred at about 80% speed (1400RPM) so at that point was theoretically 1.76HP! This of course was BS because in order to "develop" that extra HP it was no longer at rated speed and rated speed has everything to do with how a circular saw blade works, but apparently the marketing dept. had no qualms about it.
