A switch in a power box on the corner of Dungarvaon St and Brownston St blew about 5.30am.
Although many of the impacted customers were reconnected by 11.30am, some including the Otago Daily Times office, were not restored until mid-afternoon.
There were still 38 customers waiting to be connected at 3.30pm.
Further outages could be expected on Wednesday and Thursday as work continued to fix the fault, an Aurora Energy spokeswoman said.