Johannesburg – Eskom has cut power to large parts of Katlehong and Vosloorus.
The utility said this so-called load reduction will last until 9am on Wednesday.
Eskom said it was turning off the electricity to prevent network overloading in high-density areas.
It has called on residents in the areas not to report the outages.
Earlier this week, the utility announced that it would implement load reduction in four different provinces; Gauteng, Limpopo, KwaZulu- Natal and Mpumalanga.
Through load reduction, the power utility hopes to protect the grid and reduced the usage during peak hours.
Customers from affected areas are urged not to log faults during this time.