Electricity demand reached an all-time high tonight, causing blackouts to some parts of the country, Transpower says.
Thousands of people in the central North Island have been left with no power after lines company Unison responded to
Transpower's plea to lessen the burden on the network.
A Unison spokesperson said the firm's only option to comply is to perform a series of rolling blackouts.
Its website estimates around 9500 homes have been affected in areas around Taupō, Hastings and Napier.
Other lines companies have been asked to reduce load and some are managing to do so without turning off supply,
Transpower said.
The situation should have resolved around 8pm once peak demand for electricity had passed.