Power utility Eskom on Wednesday called on consumers to switch off geysers, pool pumps and all non-e.
British Prime Minister David Cameron says the recent spate of racism scandals in English football should not "drag us back to the bad old days of the past".
The abuse against black players blighted the national game in the 1970s and '80s and was thought to have been widely eradicated.
Cameron, who will host a Downing Street summit on the issue, wrote in Wednesday's edition of The Sun that "racism has come back into the spotlight."
Liverpool forward Luis Suarez served an eight-match ban for racially abusing Manchester United defender Patrice Evra. Chelsea captain John Terry is set to stand trial for allegedly racially abusing an opponent.
Cameron says that "we simply cannot brush this under the carpet ... the government stands ready to do anything it can to help."