Wednesday's power cuts, after a number of Eskom generating units broke down, put more pressure on the country's weak economy ahead of a review by Moody's on Nov. 1.
Moody's is the last of the big three credit rating agencies to have an investment grade rating on South Africa.
On the stock market, Sibanye-Stillwater led the Top-40 index higher as the precious metals miner benefited from deficit-hit palladium. The Johannesburg All-Share index rose 0.93% to 56,090, while the Top-40 index gained 0.94% to 49,855 points.