Eskom is aware of a municipal substation that blew up in Vanderbijlpark on Tuesday afternoon, spokesperson Khulu Phasiwe said in a tweet.
It is affecting power supply to large parts of that area.
Phasiwe said Emfuleni municipality is investigating the cause of the explosion. He said Eskom will assist in helping to restore power supply.
Earlier on Tuesday Eskom warned of a high risk of Stage 1 load shedding from 16:00 to 23:00 but said it would only be implemented if "absolutely necessary".
The power utility called on customers to switch off all non-essential appliances to decrease pressure on the national grid.