Eskom will be rolling out out load reduction – localised rolling blackouts aimed at easing the burden on the power grid – in four provinces, it said in an announcement on Saturday afternoon.
The cuts will be implemented in several areas of Mpumalanga, Limpopo, KwaZulu-Natal and the Free State.
The announcement came as the country was on high alert after tropical cyclone Eloise made landfall in Mozambique early on Saturday morning.
Load reduction will be rolled out between 17:00 and 21:00. Eskom did not link it to Eloise, however, but said that it was intended to avoid overloading of the network in high-density areas.
"Overloading of the network can damage electricity infrastructure by causing explosions of transformers and mini-substations. Overloading can also pose danger to people and property in the affected communities," Eskom said.
"Currently, Eskom is battling to keep up with the increased equipment failure caused by overloading that is costing millions to repair."
The storm, meanwhile, is expected to bring heavy rainfall in certain areas over 24 hours, with over 200mm possible along the escarpment areas of Mpumalanga into Swaziland and northern KwaZulu-Natal, according to the SA Weather Service.
The utility said on Friday it was working with the National Disaster Management Centre as well as Provincial Disaster Management Centres in Limpopo, Mpumalanga and KwaZulu-Natal to prepare for the storm and that it had "several" contingency plans in place. It would be covering a larger area than weather experts expected to be affected, Eskom said.
The storm was expected to cross transmission lines that import around 1 000 MW of power into SA from Cahorra Bassa in Mozambique. Wet coal was also cited as a possible risk if flooding occurred.
Eloise was downgraded to an overland depression with winds of around 55km/h after hitting Beira. Shortly before 3pm on Saturday, it was along the border of Zimbabwe and Mozambique, moving in a south-westerly direction, the SA Weather Service said.
Eloise hit Madagascar earlier in the week, killing at least one person.