A fire engulfed the Chamberlain Road Substation, causing a widespread outage.
The City said its Energy Management Directorate cleared the fault at an upstream Woodlands Substation.
This led to a loss of supply to the Mobeni Main Substation, plunging more areas in the dark.
Affected areas are Merewent, Jacobs, Austerville, Wentworth West, Mobeni South, Montclair, Woodlands Industrial and Yellowwood Park.
The City also said electricity supply would be restored in stages, on Saturday morning.
Picture: Supplied