Actually the question of 3 phase or single phase is really up to the amount of current (Amps) drawn.

3 Phase is a power distribution method to save cost on power lines and distribution copper cables. So for industrial and high power usage businesses like restaurants, etc, 3 phase is most efficient and cheaper to implement than single phase for the same Amps or current draw.

Each incoming is usually still 60A but at 120degree phase apart. At the DB board inside the house, the 3 phase incoming is distributed to all the different circuits to balance the load as best as possible. All equipment in our homes are single phase. Even water pumps in our homes are single phase since the power is abt 1HP.

Actually 60A single phase is quite alot of power for a house. This is steady load. Usually it is hard to exceed this unless there is many aircons, water heaters and pumps.

The big energy devices generally in increasing order: water pump, aircon compressors (1-2HP), water tank heaters (50l above), ovens. Instant heaters and small tank heaters are not really big power consumers.

Invertor aircons do help in smoothening the power draw when starting up and when used in multi room systems. Otherwise, if they are full on all the time, power load is the same as full on non-invertor aircon.

Here is some info:

http://en.wikipedia.org/wiki/3_phase_power
http://www.allaboutcircuits.com/vol_2/chpt_10/2.html

Cheers!