I am also looking for the right answer to what I thought would be a simple question. Which motor would be more efficient to use for our pool filter? While it is true that if you multiply the voltage and current of the same motor running 110v or 220v, you will arrive at the same power (watts). In reality, doesn't the 220 motor will run cooler because is is using less current. What about the voltage drop across the power line from the panel. Higher current means higher drop. With the motor running, if the voltage gets dropped 5 or 10 volts does the motor draw more current than if at 115v or is the efficiency decreased? The motor can't slow down; it must keep up with the 60 cycle line frequency. If the motor is running for hours in the hot sun, will that higher temperature make the motor run hotter, causing the resistance of the conductors to increase? Would that heat result in power losses? It seems intuitive that a cooler running motor is more efficient.
Also, it would seem more preferable for the current load to be cut in half and distributed between both legs, as opposed to being doubled up on one leg.
