A national grid emergency sparked a plea to the public to save power today by not charging electronic devices and only heating the room you are in as bitterly cold weather bites.
The warning came amid a fault affecting the Cook Strait cable that transfers power between the North and South islands.
Transpower said just before 8.30am that the fault was fixed and the cable had returned to "full operation".
"We are in the process of restoring controllable demand."
Transpower had earlier issued a grid emergency notice, warning of a real risk of power shortages in the North Island.
The national grid operator issued the warning just before 7.30am, declaring a "North Island emergency".
"The System Operator advises there is a risk of insufficient generation and reserve offers to meet demand," Transpower said.
The warning instructs power companies to increase generation to meet the demand, as Kiwis wake to freezing temperatures and turn on heaters.
Public urged to 'be mindful' of electricity use today
A fault has occurred in a Cook Strait cable that transfers electricity from the South Island to the North Island.
"Some power is still flowing across the cable, but a second fault could suddenly stop the flow of electricity."
Transpower spokesman Dr Stephen Jay said at this stage, people around the country would not notice any impact, as lines companies would largely be turning off controllable loads like hot water systems, which are switched on and off regularly during winter.
If the removal of controllable loads was not enough to balance the power system, Transport would need ot be ask for additional demand to be cut until the power grid is secure - meaning some households would be disconnected at some point.
Jay reiterated the message to Kiwis to conserve power this morning, in particular.
"We ask New Zealanders to be mindful of their electricity use this morning, to help us get through this situation and avoid power cuts.
"It is an unseasonable cold day, so please stay warm by continuing to heat the rooms you are using - but consider turning down the thermostat a degree or two."
Other ways people can help with the situation is to delay putting on a load of washing or using the dryer or dishwasher this morning.
Delay charging electric vehicles or electronic devices and to turn off heaters and lights you in rooms you are not using."As a result, [we are] calling on consumers to be mindful of their electricity use this morning.
