Power has been fully restored to the Ekurhuleni areas that source their power from the Allendale substation.
City Power confirmed on its official Twitter page that electricity "has been fully restored to areas around Tembisa and Midrand, that include RabieRidge,[and] Mayibuye".
Residents were left in the dark on Thursday after the substation was shut down following an oil leak scare on a transformer which had been brought in to replace one that was damaged in a fire on Wednesday.
The utility's spokesperson Isaac Mangena at the time said the shutdown was a "precautionary measure to avoid a potential disaster due to the oil leak".
The substation was partially burnt after one of its transformers caught fire on Wednesday evening.
"The fire was extinguished hours later after the substation went ablaze," Mangena told News24.
The cause of the fire was still not known.