A fire which broke out in the Stjwetla informal settlement in Alexandra, Johannesburg, on Tuesday was started by an unattended brazier (mbawula).

"Preliminary investigation by City Power suggests that the fire at the informal settlement was started by a makeshift brazier (mbawula) which was left unattended in a shack built inside the pylon," said City Power spokesperson Isaac Mangena.

The pylon caught alight and fell down, spreading the fire to nearby shacks.

Mangena warned residents against building houses along and under electrical pylons.

"At least three shacks were constructed right inside City Power’s pylon that caught fire and fell on nearby trees. Close to 200 others are built along the electricity servitude under City Power (88kv) and Eskom (275kv) overhead lines."

Mangena said it would take two to three weeks to clean up the rubble and repair the infrastructure, with costs estimated to be in the region of R3m to R5m.

City Power CEO Lerato Setshedi said the disaster could have been worse.

"Fortunately our system managed to work according to design and tripped before the live wires could reach the ground. We could be talking several casualties."

Disaster relief organisation Gift of the Givers said on Wednesday that efforts were continuing to help people who had been displaced, handing out 200 blankets and mattresses to victims of the fire.

"Initial assessment puts the number of victims at 1,500 with about 500 homes destroyed," Gift of the Givers founder Imtiaz Sooliman said on Wednesday.