Sorry about the confusion, guys!, should have known that one, at the very least!
It really depends upon the load current of the unit to be installed and of course, the
type of supply available, as a few light commercial installations over here, only have a 100A single phase supply.
Given the choice, 3 Phase wins hands down, because of smaller cable sizes and the compressors run a lot quieter.
With regard to sizing the Circuit Breaker,
you must take into account, the Start-Up current, which can be anywhere from 7-10times FLA.
But new technology over here, means that, Soft-starter units are normally fitted to Air con units, to prevent the A/C, effecting things like computers, upon start-up.