Powercor spokesman Ryan Auger said a pole fire just after 7pm in Porter Street South, Bakery Hill, was the cause of the power outage.

Mr Auger said it was believed a build-up of dirt on the insulator may have caused the fire.

He said the electricity causes a slow smoulder, which can then spark and result in a power failure to that area.

Both Coles and Safeway supermarkets, the Ballarat Police Station, traffic lights along Sturt Street and 2231 households lost power between 7.07pm and about 7.20pm.

Mr Auger said a handful of people were without power for another hour while the pole was repaired.

Powercor, Country Fire Authority crews and police attended the scene of the fire.