A nationwide request for power providers to reduce load on the national grid saw thousands of homes across Hawke's Bay without power for parts of Monday evening.
A spokesperson for Transpower, which manages the national grid, said demand for electricity across the country was at an all-time high.
Insufficient generation meant it was unable to meet demand and manage a secure system.
"As a result, Transpower has asked the distribution companies to reduce load," she explained.
"Different companies will do this in different ways, some manage via load control on hot water, some manage via customer disconnections."