The news is looking a little brighter for Auckland power users today, with Transpower bringing its second transformer at the Penrose Substation back into service overnight.

Several Auckland suburbs have suffered power blackouts over the past two days, with estimates that the costs to local businesses could run into the millions of dollars.

The problem began on Tuesday when a faulty transformer at the Penrose substation went down while another was out for routine maintenance, leaving one to cover the entire area.

But Transpower has now brought a second transformer back online after company employees worked around the clock to repair it ahead of schedule.

It says that having two transformers in operation minimises the need for any power cuts today and the chance of the second transformer failing is low. It also maintains that the failure of a cable termination on a transformer at Otahuhu is unrelated to the Penrose problem and there would be no impact to consumers.

Yesterday, lines operator Vector revealed that it had to keep usage below a certain level to keep the pressure off the network. With insufficient savings, Vector temporarily cut power to the mainly residential St Heliers to keep demand below the necessary level.

Transpower spokeswoman Adele Fitzpatrick tells NBR that while there was a drop in the power usage yesterday, it was not quite enough to avoid the blackout. However, she says usage should return to normal with the transformer now working again.

Ms Fitzpatrick says the third transformer was now being repaired, but could not put a timeframe on when that would be completed.

“We still need to find that original fault, and these things are the size of a bus, so it’s impossible to say how long it will take.”