December power outage in Cape Town's CBD explained: This is how and why it happened

In December, the Cape Town CBD, the Atlantic Seaboard, Camps Bay and parts of Woodstock were affected by a blackout. Picture: Armand Hough/African News Agency(ANA)

In December, the Cape Town CBD, the Atlantic Seaboard, Camps Bay and parts of Woodstock were affected by a blackout. Picture: Armand Hough/African News Agency(ANA)

Published Apr 7, 2022

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Cape Town - The power outage in December, which left the Cape Town CBD and Atlantic Seaboard areas without electricity, “had an extremely low risk of occurrence, akin to a 100-year flood”, said the City of Cape Town.

This comes after the City announced that repairs to the damaged power infrastructure in Montague Gardens and the Foreshore had been completed.

The damage resulted in 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 re-routing of supply.

The City’s Electricity Generation and Distribution Department not only completed the repairs to electricity infrastructure but 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 events.

Eskom technicians outside the City of Cape Town's Acacia High Voltage Substation near Century City at the time of the outage. Picture Henk Kruger/African News Agency(ANA)
Eskom technicians outside the City of Cape Town's Acacia High Voltage Substation near Century City at the time of the outage. Picture Henk Kruger/African News Agency(ANA)

Mayco member for energy Beverley van Reenen said: “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 through 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,” Van Reenen said.

“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.”

Van Reenen added: “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.”

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