Why 3-phase is used in power system?

My currnet a/c is on 3-phase and I'm going to replace it. I want to get a 5 ton 16 SEER ($1500 gov't rebate)but they are available in only single phase. I'm wondering if it will cost significantly more to run a new 16 SEER unit on single phase than a new 13 SEER on 3-phase.

Hi, What is it that makes 3 phase power more efficient? Suppose I need an air compressor for a printing shop and I can choose between a 7.5HP single phase and a 7.5HP 3 phase. Ignoring that the cost of the motor is a little less for 3 phase, why is the motor more efficient and how does...

What is the differencve between single phase power and three phase power?

How would one decide on which to use either 3 phase or single phase power to heat an airplane hanger?

Is there any real difference in efficiency and cost between a single phase air conditioning unit and a three phase unit? Thanks, JPGREEN