Homes from Shag Point to the Waitaki River and inland to Duntroon were plunged into darkness about 5.45pm. Power was not restored until about 7.30pm, Network Waitaki chief executive Graham Clark said last night.
Landline telephones were also unusable.
"It was an event we would rather not have had ... Nearly two hours without power is an exceptionally long time and not something we would experience very often."
He was "strongly of the opinion" the fault occurred at Trans- power's grid exit point at Weston, rather than anywhere on Network Waitaki's system. Work had been carried out at the grid exit point during the week and had been commissioned shortly before the cut, he said.
Network Waitaki and Transpower engineers located the fault and fixed it, he said.
Oamaru police said last night they had not attended any callouts or emergencies because of the outage.
A St John spokeswoman said the power cut set off some personal emergency alarms. Ambulances were sent to investigate as a precaution because occupants could not be contacted by telephone. No-one had required assistance.
Householders dug out candles and torches, and the Otago Daily Times received several reports of people checking on friends and relatives living alone.
Many of those without heating went to visit friends with log burners, Oamaru Fire Brigade station officer Brett Delamere said.
The brigade attended one callout, to a large lpg tank in Dee St, where the computerised security system malfunctioned and set off the sprinklers. Officers shut off the water.
Oamaru Hospital and rest-homes were not affected, as their emergency generators kicked in, Mr Delamere said.
However, Oamaru Civil Defence staff and volunteers found themselves in the dark temporarily. They were holding a social function at the fire station following a debriefing about the handling of the recent floods and had to wait a few moments for the station's emergency lighting system to start.
Mr Clark said people would have been inconvenienced by the outage, as it had occurred during a meal time.
