Moisture blamed for Heathrow power outage after substation fire, report finds
A fire that triggered a major power outage and shut down Heathrow Airport in March was likely caused by moisture entering electrical equipment, according to an official review.
The National Energy System Operator (NESO), which was tasked by the energy secretary to investigate the incident, concluded that the blaze at the North Hyde substation in west London was "most likely caused by moisture entering the bushing," a critical component that helps transfer electrical energy between parts of the system, News.Az reports, citing foreign sources.
The fire broke out late on March 20, forcing Heathrow Airport to close the following day. The sudden shutdown led to thousands of flight cancellations and left countless passengers stranded. NESO confirmed that the outage affected 66,919 domestic and commercial customers, with approximately 270,000 journeys disrupted as a result.
The review explained that the moisture caused a short circuit inside the bushing, which likely led to an electrical arc—sparks that ignited the oil within the equipment when combined with heat and air.
Bushings are mechanical devices designed to insulate and manage the flow of energy between electrical components. In this case, a failure in the insulation process had catastrophic consequences.
Authorities are now reviewing safety protocols for substations in high-risk and high-impact zones, particularly those supplying essential infrastructure such as airports.
Further recommendations are expected in the coming weeks to prevent similar incidents in the future.
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