City Power in the Johannesburg city centre has restored power to 40% of the areas that were affected following cable theft this week.
Around 20 streets had been affected for almost a week following theft of copper cables in the inner centre.
City Power spokesperson Sol Masolo said the technical team, which worked throughout the day, is currently testing equipment and cables that have been installed to replace those that were stolen, damaged or burned in the remaining 60% which is still without electricity.
"Our teams remain committed to work throughout the night and if needs be, throughout the weekend, until the last customer is switched back on," said Masolo in a statement.
"City Power once more apologises to all affected customers and requests their patience while it continues with its work."
Most parts of the city centre were without electricity for the week.
Several businesses could not operate and complained of a loss of revenue.