To clean up all of the confusion about our system voltages over here, I am currently reading the new AS/NZS 3000:2002 Standard for Electrical Installation, it states that all voltage drops within an installation (anywhere in the installation)shall not deviate any more than +/-6% of the nominal supply voltage, regardless of whether it is single or three phase supplied.
With regard to the voltage in Australia, I
think that they have always used the 240/415V system over there,not too sure.
New Zealand is slowly being "harmonised" with Australia, with respect to Regulations and so forth, our registration requirements are now the same,because of a lot of NZ sparkies,going over there to work.