Power is out in parts of the far north of the North Island while crews repair damage to the main electricity line into the region.
Lines company Top Energy said the power cut is expected to last about nine hours, and will affect all districts north of the Mangamuka Gorge.
It said there will be a separate power cut for about an hour at 5pm today, for eastern parts of the area.
The company's chief executive Russell Shaw said the work was part of making the power supply more reliable, and repairing some of remaining damage from last July's bad storm.
He said people should treat all electricity lines as live throughout the power cut, as they would be restored without warning.