A transformer fault at the Penrose substation caused a power outage that affected 74,000 businesses and homes in the eastern suburbs of Auckland today.

Transpower spokeswoman Adele Fitzpatrick says the fault occurred at 1.10pm. Businesses across Newmarket, Penrose, Parnell and Ellerslie areas were forced to shut their doors.

Fire Service senior communicator Mau Barbara says firefighters were called to put out a fire in the the transformer and blazing power lines in Scarborough Lane, Remuera.

Mr Barbara says the Fire Service rescued four groups of people stuck in lifts as a result of the power cut.

“Two of those incidences were at the Central Park Buildings, in Buildings 2 and 4, and we also had people stuck in a lift at the Broadway shopping centre in Newmarket,” Mr Barbara says.

Fire fighters were called to the University of Auckland Tamaki campus for four fire alarms set off as a result of the outage. Bill Williams, senior communications adviser for the university, says that no teaching was under way at the campus during the outage.

"The Epsom campus was also affected. We had a dozen summer school classes on professional development and education teaching at the time but they continued. The power returned just before 3pm," Mr Williams says.

A further 11 businesses and homes required Fire Service assistance for alarms activated due to the power cut, including Courier Post Onehunga and the Employers & Manufacturers Association in Khyber Pass.

An Auckland City Council spokeswoman says, “Traffic lights in the Eastern suburbs were affected. We are still assessing them and it’s hard to say how many at this point.” No traffic incidences have been reported.

Greenlane Hospital was without power but ran on generators. “Essential services are in place and all patients are safe,” Auckland District Health Board general manager of operations Ngaire Buchanan says.

“Some outpatient clinics which do not require access to a computer system are still being run, but most others will be cancelled. If patients do have a clinic booking for this afternoon we advise them not to come,” Ms Buchanan says.

Auckland City Hospital’s computer systems were offline. However, all critical services were running and patients were safe. Middlemore Hospital in Otahuhu was unaffected.

White Cross Accident and Medical Clinic in Remuera lost all power during the outage. “A generator from the hospital provides some power, but only for lighting. All our X-ray machines are down,” a spokeswoman says. “We’ve got to do everything manually as the computers are down. We also have no eftpos. It makes things a bit more difficult.”

All retailers in the Sylvia Park shopping centre were unable to trade during the outage except for Foodtown and PAK'nSAVE, which had private generators.

“We’re the only ones trading. The rest of the mall is down,” Foodtown assistant store manager Ben Aro said at 2.30pm.

The Warehouse in Newmarket had to evacuate customers during the outage. "We have had to shut our doors. We have no air conditioning so it is very hot," a spokeswoman says.

Transpower reported that it was restoring electricity as quickly as possible.

“A staged restoration is in progress, but at this stage it is unknown how long this will take,” Ms Fitzpatrick says.

Update: At 4pm Ms Fitzpatrick said power was being progressively restored and that 20,000 homes and businesses in Orakei, St Heliers and Glen Innes are still without power.

"The faulty transformer was one of three. One transformer was out due to routine maintenance. The other two were handling the load until an electrical fault in one caused the third transformer to trip," Ms Fitzpatrick says.