Power utility Eskom on Wednesday called on consumers to switch off geysers, pool pumps and all non-e.
"This year we hope to break the Guinness Book of World Records with more than 20 million South Africans singing," Basic Education Minister Angie Motshekga and Lead South Africa said in a statement. "We want to encourage the nation to join in."
Last year, the department and the civic participation group arranged for millions of school children to sing to Mandela at 8am on his birthday.
Lead South Africa spokesman Yusuf Abramjee said he was confident that the public would show their love and affection for Mandela by participating in singing to him on his 94th birthday on Wednesday, July 18.
"In addition to the millions of school children, we want people in offices, in factories and those out on the streets to join in."
The SHOUT Foundation, a movement aimed at reducing crime, committed 94 singers to record the song for distribution in the run-up to Mandela's birthday.