Hi Don;

I think that a 1HP motor will cost essentially the same to run at either voltage, using 0.746KVA+/hr. Magnetic flux is proportional to NI, number of turns x the amperage. To generate the same rotational flux at 1/2 the current, the motor must be rewired so twice the number of turns are effective. The I^2R losses in a comparison of the motors are now proportional to current, not exponentially related.

I know what you were trying to say, but the largest unused energy that you pay for in an electric motor has to do with power factor - That is, the motor inductance causes a phase shift between the applied voltage and the resultant current. Your electric meter misinterprets what is going on, and you pay for more than you are actually using. Coincidentally, the 220V motor will have a proportionally higher inductance than a 110V motor. In larger shops where this amount to lots of bucks, they correct the power factor on each motor so that the electric company's meters read the correct usage. At the power levels we're talking about in a small home shop the savings gained from either changing voltage or correcting PF would be negligible - But those 220V wired motors sure seem to run stronger! And in my opinion, that's where your improvement in I^2R losses really show their importance.

Best Regards, Spidey