London, England — A recent report has shed light on a significant fire incident at an electricity substation that led to Heathrow Airport’s closure, disrupting travel plans for more than 200,000 passengers for nearly an entire day. The National Energy System Operator (NESO) has disclosed key findings, indicating that the National Grid had prior knowledge of issues related to the substation, which could have averted the chaos.
The investigation revealed that moisture build-up likely ignited the blaze. The fire originated in a “supergrid transformer,” which plays a crucial role in reducing high-voltage electricity for distribution to Heathrow and nearby areas. Inspectors noted that water intrusion in the insulation surrounding the transformer connections triggered a short-circuit, leading to “arcing” and ultimately a catastrophic failure that resulted in a fire fueled by the cooling oil of the transformer.
Alarmingly, the report highlighted that National Grid had been made aware of moisture concerns at the substation back in July 2018. Guidelines indicated that the faults detected were urgent and warranted immediate replacement, yet no action was taken. The situation deteriorated further when maintenance, planned for 2022, was postponed, and subsequent attempts to schedule repairs failed.
Heathrow Airport officials had been aware that a failure in one of its three connections to the national grid could lead to a temporary closure. Given its heavy energy consumption—comparable to that of a small city—the airport understood the implications of losing a connection, requiring a closure of up to 12 hours to transition key systems. Despite this knowledge, the airport deemed it too costly to address the potential risks, with estimates to enhance resilience reaching up to a billion pounds.
Moreover, there was a lack of awareness among National Grid and local network operators about the critical nature of the substation’s supply to Heathrow. While they recognized that electricity from the North Hyde facility powered the airport, they were unaware that an outage would necessitate the airport’s closure. Current protocols do not clearly identify which customers are classified as “critical national infrastructure,” encompassing sectors such as transport and government. The report called for improved communication between energy suppliers and operators of critical infrastructure to prevent future disruptions.
In the aftermath of the fire, Heathrow has faced scrutiny, particularly regarding the leadership response. The airport’s management indicated that the report was not intended to attribute blame; however, Heathrow has voiced dissatisfaction and is considering legal action against National Grid. The airport contends that the report outlines “clear and repeated failings” that contributed to the disaster, and expects the National Grid to acknowledge its role in the situation.
National Grid has maintained that it operates with a comprehensive maintenance strategy and intends to cooperate fully with ongoing investigations. As the review progresses, both organizations face mounting pressure to address systemic weaknesses to ensure the reliability of essential services in the future.