The national grid operator Transpower announced a power emergency in the North Island on Friday morning.
It issued a two warning notices that there was a risk of insufficient generation to meet demand in the North Island.
It's asked for more offers of power from generators and for local lines companies to manage demand as necessary.
The warning comes after a sudden cold snap has moved up the country in recent days.
Power systems consultant Brian Leyland spoke to Corin Dann.
