Manukau City Mayor Len Brown says Auckland must look at alternative sources of electricity to ensure that the power stays on.
About 70,000 businesses and households in parts of the upper North Island lost power for up to four hours on Monday afternoon after a fire beneath transmission lines on a farm in Waikato.
Construction of a new power line between South Waikato and Auckland has just begun.
But even when that upgrade to the national grid is completed, Mr Brown says there will be no guarantee of supply.
He says being dependent on one power source coming from the south will not be able to sustain Auckland's future development.
Mr Brown says solar, wind and sea power are all options to be considered.
Transpower chief executive Patrick Strange says the real solution is to build alternative transmission lines to Auckland.