I'm not sure, but believe it's probably due to voltage sag on the 120v circuit. Most are wired with #12 AWG wire, with an ampacity of 15 amps per the National Electrical code. When a 1.5 hp or 2.0 hp single phase motor is started on 120v, there's a huge current draw that causes a voltage sag (the lights dim). When that same size motor is started on 240v, half the current is drawn and the lights don't dim.so at 220v it has fewer amps running through it. Could this be why?
That's part of the equation. Heat is the killer of motors. You have the first part right, since the voltage is doubled the the current is halved. With only half the current running through the motor windings, you cut the heat losses by a facrtor of four. The heating is caused by the resistance of the motor windings themselves. The power formula to be concerned with for the heating situation is not the voltage times current one already mentioned, but a different way of saying the same thing. For heating discussions, power being equal to the current squared times the resistance. Since current is squared, twice the current in a 110V wired motor will produce four times the heat of the same motor wired for 220V (theoretrically speaking of course). That additional heat will speed up the degradation of things like the varnish coating or insulation on the wires in the motor. Once you have a weak spot in the insulation, you can form a full or partial short --> more current --> more heat --> more damage ............. continued worsening untgil failure.
If you can find a local shop that orders steel on a regular basis, they may let you combine your order with theirs. Delivery is free, as long as the combined order is over $500, but you do have to buy in full stick lengths - 20' and 24' are the most common for steel, although aluminum sticks are 12'. That means you have to bring a long trailer or a way to cut the sticks to pickup bed length.
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