In article 1078204646.761648@smirk,
wrote:

What amperage breaker does one need for a 5HP table saw on a 240V
single phase circuit?

My logic: Typically, single phase 5HP 240V (or 230V) motors are rated
at 19.8 or 20 A. Given that a circuit is supposed to be loaded 80%
(look it up in the NEC sometime), this means a 25 A breaker would be
borderline sufficient, and that a 30A breaker should be generous.
With a slow breaker (not a fuse), there should be no problems with the
startup surge of the motor tripping the breaker.


Using Ohm's law this is a relatively simple question to answer...

1 horsepower = 745.7 watts

Power (watts) = I (amperage) x E (voltage)

When you have two values for the variables in the equation you can
figure out the third.

P 3728.5 (watts 1 HP x 5)
Therefore I = --- or I = ------
E 230 volts


230 volts = 16.21 amps
240 volts = 15.53 amps


Using the "80% rule", a 20 amp breaker should not exceed a continuous
load above 16 amps. It seems to me, that with the proper type of "slow"
breaker, you should be OK with a 20 amp breaker.


Joe


PS

I am not an electrician or an electrical engineer. In fact, I have
never even played one on TV.