Power has been restored to more than 500 Auckland houses after an outage early this morning.
Vector spokeswoman Sandy Hodge said power was cut to 857 houses in Hillsborough just after 6.30am.
As of 7.45am, power had been restored to 506 houses, she said.
A Hillsborough resident told the Herald of hearing a loud explosion this morning.
Ms Hodge said rain water could get into an insulator and make a loud bang.Power was expected to be restored at all affected Hillsborough homes by 9am.