115V vs. 230V

CDH said:
Actually, the same motor when wired for 230 VAC will use slightly less power because it will run more efficiently. It will run at less amps and amps * resistance == heat generated and every bit of heat generated is lost efficiency...not to mention shorter life of the motor.

As a general rule, high voltage is more energy efficient than high amperage...sometimes a lot. That's why transmission lines run at such high voltage.
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You are absolutely correct CDH. Under small loads, there is very little difference in the efficiency of 240v vs 120v. It's when the load increases that higher voltages really shine by minimizing losses.

Erin F. Burke, PE ;):D;)
Big Washington Power Company:p
 
I just wanted to follow up here, I also work in the electric industry, although I'm not an engineer. I work for a software company that works with electric co-ops, so I called the engineering dept of one of our larger co-ops and spoke with their lead guy about this. He tells me that they charge based on KWH from each leg separately.

In the example from before, if we put a 20A load on one leg and a 3A load on the other, the meter moves to register a total of 23A. On 240V service it's metered slightly differently because there is a negative load, but the end result is that you get billed by the watts you use.

There is surely some merit to the efficiency argument (as previously mentioned, it is likely minute), but, at least in my area, it doesn't appear that we get billed an average of the two legs.
 
And it gets even more confusing when you are talking about certain types of electric gear. High end Class A and A/B stereo power amplifiers need current and lots of it. You will see some guys running seperate circuits of 20-30 amp 110 just for the amplifiers. Amps that operate in true Class A are the worst. They are not only current hogs but they can also be used a a space heater for your listening room in a pinch becaus they run hot.
 
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