What happened

A technical fault at the Kerawalapitiya Grid Substation triggered a nationwide cascading power failure in Sri Lanka beginning around 12:30pm local time on 17 August 2020. A three-phase fault at the Kerawalapitiya thermal power plant took unusually long to clear, which depressed voltage at the nearby Lakvijaya thermal power plant; both facilities isolated themselves from the grid in response, causing a rapid nationwide frequency decline that protective systems could not arrest, blacking out the entire country. Power was restored by around 8:30pm, roughly seven-plus hours after the outage began. A Ministry of Power spokesperson initially and inaccurately attributed the outage to a failure at the Yugadanavi power plant before the Kerawalapitiya/Lakvijaya cascading-fault explanation was established; Minister Dullas Alahapperuma initially said restoration would take about two hours, but the process was delayed by the cascading nature of the failure. The Ministry of Power appointed a special committee to investigate the root cause. This was described by officials and local media as the worst nationwide blackout Sri Lanka had experienced since 2016, and is documented as an accidental technical/protective-system failure, not an attack.

When cited sources give different casualty, damage or spill figures for this event, they’re reported side by side above rather than merged into one number. See how confidence levels work.