Transpower came very close to power cuts in the wider Christchurch on Tuesday night, but says it won't have to repeat its call to conserve electricity in the cold snap.
The national grid operator put out the request to residents in Christchurch, Rangiora and Kaiapoi just before 6pm, when power use was spiking amid a cold snap, because one of its substation transformers was out for repairs.
It also worked with lines companies MainPower and Orion to switch off controllable load, such as hot water systems.
"About five o'clock we got the call from the system operator that load was peaking higher than had been forecast," Transpower grid delivery general manager Mark Ryall said.
With one of three transformers in Islington needing repair, the operator needed to protect the other two from being overloaded by reducing demand. It had now reconfigured the other two transformers.
"Load was getting very close to the limits of one of the transformers when the action was taken."
Ryall said even with the repair still going on, the operator would be able to manage demand.
"We actually made some changes in the network to enable them to make changes automatically if the same thing happens again this morning so there should be no issue."
Ryall was confident the situation was under control and South Islanders did not need to worry about further threats of power cuts.
The third transformer would be back online on Friday, and a fourth one would be added in a couple of months, so the problem shouldn't happen again, he said.
On Wednesday morning Christchurch was at a wintry 5C and temperatures were not expected to go above 10C all day.
RNZ
