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 had no power last night after lines company Unison responded to Transpower's plea to lessen the burden on the network.
A Unison spokesperson says the firm's only option to comply is to perform a series of rolling blackouts.
Its website estimates around 9500 homes were affected in areas around Taupō, Hastings and Napier.
Other lines companies had been asked to reduce load and some are managed to do so without turning off supply, Transpower says.
Powerco, which runs the supply in Tauranga, who did its bit to respond to Transpower's request for electricity lines companies nationwide to reduce load on the national grid.
Controlled hot water systems across Powerco’s electricity network areas were temporarily switched off to reduce network load and avoid the need to disconnect any customers.
Powerco General Manager Service Delivery and Systems Operations, Karen Frew, says customers’ hot water systems will progressively be switched back on through the night once peak power load has passed and Transpower provides instructions to do so.
“Thank you to our customers for your understanding.”
The situation should have been resolved around 8pm, once peak demand for electricity had passed.