Officials at St Albans Correctional Centre in Gqeberha used generators overnight to supply power to the facility, following Wednesday's explosion and fire at the local sub-station.
The Department of Correctional Services said the supply was totally cut-off.
But, spokesperson Nobuntu Gantana, said each centre has a generator and that additional diesel was available.
Meanwhile, Nelson Mandela Bay Municipality says that the vandalism of the sub-station led to the eventual fire.
Spokesperson, Kupido Baron, says transformer earths were stolen and work is underway to restore supply to St Albans.
Nobody was injured in the explosion and the fire was soon brought under control by local firefighters.
