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Grid infrastructureTaiwanEIR-1283

Fire at Wanlong substation cuts power to more than 300,000 households in Taipei

Dec 2021Published 25 Sept 2026Responsible editor: Chief Editor

SignificantElectricalProvisional
Estimated damageEstimated by the register's adjusterHow? Know the real figure?
Figure hidden: shown to subscribersLow confidence
supply cut for about •• daysShown in the record →Full estimate
From the recordRoot cause hiddenFailed part hidden
Where
Wanlong substation, Taipei's Wenshan District
Operator
Taiwan Power Co
What
No. 5 distribution transformer malfunctioned and insulating oil caught fire
Injuries
None reported
Cause
Malfunction of the No. 5 distribution transformer

Companies named in the reporting of this entry (being named is not a finding of fault): Taiwan Power

What happened

A fire at Taiwan Power Co's Wanlong substation in Taipei's Wenshan District cut power on 12 December 2021. The city government said Taipower reported a mechanical malfunction that led to the fire, and that the substation's 161 kV and 69 kV supply systems were shut off. Taipower later said the No. 5 distribution transformer malfunctioned, its insulating oil caught fire and smoked, and this led to an insulation failure and a shutdown of supply systems.

The fire department said a report was received at 9:56am and the fire was put out at 10:26am, with no casualties. Taipower said 305,418 households in Taipei's Wenshan District and New Taipei City's Sindian District were affected, and that power was restored to those households and facilities by 1:07pm. The outage also shut down some water purification plants and booster pump stations until emergency generators and restored power allowed operations to resume.

Contributing factors

Taipower said a malfunction of the No. 5 distribution transformer caused its insulating oil to catch fire and smoke, which led to an insulation failure. The city government described the initiating event as a mechanical malfunction. No independent cause beyond that account is reported.

Lessons learned

  1. A distribution-transformer malfunction that ignites insulating oil can take 161 kV and 69 kV supply systems offline and affect several hundred thousand households.
  2. A substation outage can also stop water purification and pumping, so emergency generation for those plants needs to be available.
  3. A prompt public account of the equipment failure, and of the reserve margin at the time, can counter rumours that the outage was caused by a national supply shortage.

More lessons on outages, backup supply and restoration, from every incident on the register.

Not yet known

  • Exact model and age of the No. 5 transformer
  • Full root cause of the mechanical malfunction
  • Cost of damage and repairs

This entry is updated when these are reported. Get an alert for the next one like it.

Source

Taipei Times (taipeitimes.com)

Other entries that name Taipei

Published 2026-09-25. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.

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Chart to reuse with this story: Grid infrastructure incidents by year, free with a credit (PNG).

Grid infrastructure incidents in Taiwan: 6 entries, with a free alert for the next one.

Substation and transformer fires: the counts, the latest entries and a free alert for the next one.

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