Tens of thousands of homes and businesses were without electricity in the upper North Island on Monday due to a massive power cut.
Electricity grid operator Transpower says power was cut from Huntly in Waikato to Cape Reinga in Northland after problems with a transmission line on Monday afternoon.
Transpower says the outage was caused by a fire in trees on private property beneath two transmission lines south of Auckland.
Power was restored by about 9pm after workers fixed the faults on the transmission lines.
Lines company Vector had asked other lines companies in Waikato, Auckland, and the Whangarei district to cut power in some areas from mid-afternoon in order to reduce consumption.
Northpower network manager Richie Dempster says it was forced to cut power to about 5000 customers about 3.45pm - the worst possible time for farmers, as they were about to milk cows.
Transpower chief executive Patrick Strange says the fault could have been fixed sooner, but workers were delayed by several hours when the farmer who owns the land beneath the transmission lines refused them access.
Dr Strange says major lightning storms and the fact two other transmission lines were out of service meant there was already a lot of pressure on the power supply.
In Auckland, commuters faced disruptions as traffic lights were out, and rail services were affected in the afternoon.
Auckland City Mayor John Banks says power cuts happen far too often and estimates Monday's would have cost the city millions.