Sorry that no-one has replied back regarding your query.
There are extra costs with installing three phase rather than having one single phase.
Rather than two wires coming into the Residential Switchboard you will have four wires.
Installation of the wiring should cost more as the phase/breaker is normally added to the power points to identify them.
The load for the house is normally tried to be made balanced to even the load on the street to assist your Electricity Supplier in balancing their distribution load.
Daily supply costs are normally the three times the amount (say single phase costs $1.00 three phase costs $3.00) this would add approximately $120 more to each bill each quarter. At $0.40 a kW that is the same as using an extra 300 kW a quarter of power on a single phase system.
If you are considering have a large freezer / cool room, pool, large workshop etc it may be of benefit, but remember then you should be using three phase devices to get the benefit which comes with increased install and capital costs.
A quick look at Retailer pricing for residential did not find a reduced rate for having three phase.
For a general household it is not normally of benefit.
Another reason that you may decide on three phase is if you are planning on having a large solar array on the property.
I would suggest that you engage the services of an electrical engineer or do lots of research on the Web (make sure they are Australian sites though) before deciding on which way to go.
Don't report that people are wrong when you have not properly read the reply.
My statement was that you pay three times the supply charge.
There is some chatter that Sydney may try to ban petrol and diesel vehicles by 2027.
ACT has stated by 2035 it will ban petrol and diesel vehicles. The 2035 date refers to the end of petrol and diesel new-car sales – referred to as to "start phasing out light internal combustion engines.