Reports say power has been down in areas including Johannesburg and Pretoria since 6am.
This weekend Eskom’s limited generating capacity is due to urgent planned maintenance.
Hawks say a syndicate may be at play after two Eskom employees attempted to defraud the utility.
Eskom is battling fuel shortages, financial constraints and rolling blackouts.
The pair was apprehended along with an accomplice during a sting operation at the weekend.
Eskom says until its generating ability and finances improve, SA should be prepared for load shedding.