KEY POINTS:
Hospitals, homes and businesses in eastern Auckland had to cope without electricity for up to two-and-a-half hours yesterday afternoon when a transformer broke down at the Penrose substation.
The fault, at 1.10pm, cut off 74,000 customers.
Power was gradually restored, with Newmarket and Sylvia Park shopping centres being resupplied after 90 minutes.
Orakei, St Heliers and Glen Innes had power supply resumed by 3.30pm.
Shops in Newmarket and Remuera closed their doors after the blackout began, four people were freed from lifts, operations were cancelled at Green Lane Hospital and Ascot Hospital and motorists proceeded cautiously through deadened traffic lights at intersections across the city from Panmure to Mt Albert.
"It was set to be a big day for Newmarket, but the rug was pulled out from under us," said a furious Cameron Brewer, who heads the Newmarket Business Association.
"When you consider everything from wasted restaurant meals, employees unable to work, wiped computer documents and missed electronic sales, the cost would have to be several million dollars.
"Given the cost of power, business now deserves a full explanation," said Mr Brewer.
Transpower chief executive Patrick Strange said the outage was "our worst nightmare" and the transformer was being taken apart in order to find out why it failed.
He said three transformers usually took the load at Penrose but yesterday one of them was out for regular maintenance. Normally, two transformers could cope but this time one of them failed and this caused the remaining one to trip.
Mr Strange said Penrose was now relying on one transformer while staff worked round the clock to try to have a second one in use some time today.
He appealed to consumers to go easy on electricity use during this morning's 7am to 10am peak-use period in order to avoid a further outage.
"This time, it was not as big as the last one," he said, referring to the 2006 outage caused by a fault at the Otahuhu substation."But it's the second one in four years in Auckland and our view is that it's one too many."
Mr Strange said a new replacement transformer had been ordered to reinforce Penrose and a major upgrade at Otahuhu was under way.
Safety advice is being issued after raw sewage was discharged into the Waitemata Harbour following the power cut. Auckland Regional Public Health Service is advising people to take extra care with food and water.
The raw sewage was discharged after power to the Orakei and St Heliers pumping stations failed temporarily.
Medical officer of health Dr Cathy Pikholz advised people to keep away from any sewerage overflows, and to avoid swimming close to St Heliers Bay and Okahu Bay for the next 48 hours. Dr Pikholz also advised people not to collect shellfish from the affected areas.
