Eskom says that SA's power system remains "constrained and vulnerable" after unplanned breakdowns increased on Monday evening.
While it is not planning to institute rotational power outages on Tuesday, it warned these may be implemented at short notice.
The utility did not say what caused the breakdowns to increase from 10 500 MW to above 11 000 MW of SA's generation capacity.
"The probability of load shedding remains for [Tuesday], but will only be implemented if absolutely necessary. There is sufficient diesel for our open cycle gas turbines and water at the pumped storage schemes to supplement the shortage of capacity, if necessary," it said in a statement on Monday night.
Eskom previously said that when unplanned breakdowns rise above about 9 500 MW it starts to use emergency resources "at a high rate," increasing the probability of load shedding if the supply constraints are sustained.
"Eskom’s technical teams are working tirelessly to return units from planned and unplanned maintenance and to replenish emergency reserves."