"Aaron Fude" wrote in message ...
When translating amps to hp for a 120V appliance, is the formula essentially

120*amps/745.699872

That would give a 15amp ryobi table saw a rating of 2.41hp which is ridiculously high, no? Is my
formula not right, or is 2.41hp not ridiculous or is there something else I'm missing?

Well if it was a Craftsman shop-vac, it would make perfect sense... they have no problem claiming
they can get 5 or more horsepower out of a 120V outlet! That level of power is achieved by using an
old sales technique called "lying" ;^)

Your calculation is fundamentally correct but leaves out the effect of efficiency. 80% is a
reasonable, maybe a little optimistic level of efficiency for a small electric motor. So if you're
putting in 2.4 HP of electrical energy, you'd get 0.8 * 2.4 = ~1.9 horsepower out of the motor.
Then you're going to lose some more in the gears, bearings, etc. So you maybe get something like
1.5 HP at the blade?

It's also probably not rated to produce that kind of power continuously. It can do it for a few
seconds or maybe tens of seconds, but longer than that and you'd probably smoke the motor.

Eric Law