"The risk of load shedding is high, but at the moment we have not started because we are able to continue generating electricity," spokesman Khulu Phasiwe said.
"Our engineers are busy investigating the cause of the breakdown."
On Friday, Eskom said the risk of power cuts during December was low. Spokesman Andrew Etzinger said things were starting to look up for the power utility.
In recent weeks, the utility has battled to keep the lights on since the collapse of one of its coal storage silos, diesel shortages, and maintenance issues.
On December 5, Eskom implemented stage three load shedding. Stage one allows for up to 1000MW of the national load to be shed, stage two for up to 2000MW, and stage three for up to 4000MW.
On December 8, Eskom CEO Tshediso Matona said the country did not have a power supply crisis.