Cape Town December outage had very low risk of occurrence

Repairs to the damaged City of Cape Town power infrastructure in Montague Gardens and the Foreshore have been completed. The damage led to a large outage in the CBD and Atlantic Seaboard areas in December 2021 following a fire that was started under an Eskom cable bridge structure. All supply was restored at the time to the affected areas via rerouting of supply. The incident had a very low risk of occurrence. Read more below:

The City’s Electricity Generation and Distribution Department completed the repairs to the Montague Gardens and Foreshore electricity infrastructure. It has also completed its investigation into this outage.

The City’s investigation found that on 20 December 2021 a series of multiple tripping feeders resulted in the loss of supply to Area 7. At the time, the cause of the outage was thought to be the Eskom Acacia – Tafelbaai 132kV overhead line that fell with its conductors across the N1 roadway.

The City’s subsequent investigations revealed that the City’s Montague Gardens – Foreshore and Eskom’s Acacia – Tafelbaai 1 132kV Feeder cables were severely damaged by the fire that occurred in the Eskom-owned Swart River Cable Bridge in Paarden Island, which caused the chain of unfortunate events.

‘The root cause of the outage was caused by a fire which was started under the Eskom cable bridge structure. This resulted in severe damage and the subsequent failure of high voltage cables, running though the secured purpose built concrete bridge.

‘The cause of the Eskom overhead line failing was as a direct result of the magnitude and duration of the fault current being fed back on the earth return path, resulting in the ground wire burning off at a number of the overhead line towers and falling across the phase conductors and onto the ground and N1 roadway. It is important to note that none of the veld fires that occurred is believed to be sabotage.

‘I am pleased to hear from officials that this fault had an extremely low risk of occurrence, akin to a 100-year flood. We once again thank the teams for their quick work in attending to this large outage. For added security and to mitigate any future risk, the cable routes of those circuits now feeding the Central Business District have been rerouted under the Black River and are being closely monitored on an ongoing basis.

‘We are grateful to the City staff for attending to large area outages across the metro as quickly as possible, often working through the night to ensure residents have electricity,’ said the City’s Mayoral Committee Member for Energy, Councillor Beverley van Reenen.

Source: City Of Cape Town

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