Heathrow's closure linked to faulty transformer that wasn't mended
In an unexpected turn of events, a fire at the North Hyde substation in West London, affecting London's Heathrow Airport, has been found to be a result of a moisture-related failure in high voltage components. The incident, which occurred on March 20, 2025, has raised concerns about the importance of maintaining electrical infrastructure and addressing potential vulnerabilities.
While the specific fire at the Hayes substation was not directly linked to moisture, electrical substations are generally susceptible to environmental factors such as moisture. Moisture can lead to equipment failure and fires due to the risk of short circuits and electrical discharges. Although past incidents at Heathrow or nearby substations have not been specifically mentioned as moisture-related, the general concern about moisture in electrical systems is well-documented.
The fire likely started with a short circuit in a transformer, caused by moisture that had entered the components. This moisture caused a short circuit, which then resulted in sparks that ignited the oil. The fire subsequently affected a backup generator, exacerbating the impact on the airport.
Following the incident, the government-commissioned report concluded that the "catastrophic failure" was due to the deferred maintenance opportunity in 2022 and the failure to implement mitigating actions appropriate to the severity of the moisture reading in 2018. Controls in place also failed to identify that action had not been taken in relation to the elevated moisture reading.
In response to the incident, the National Grid has stated they support the recommendations in the report and will cooperate with Ofgem's investigation. Ofgem has opened an official enforcement investigation to consider any possible licence breaches by the National Grid. Energy Minister Ed Miliband found the report to be deeply concerning, as known risks were not addressed by the National Grid Electricity Transmission.
The airport has welcomed the report, stating it sheds further light on the external power supply failure. The airport believes a combination of outdated regulation, inadequate safety mechanisms, and the National Grid's failure to maintain its infrastructure led to the catastrophic power outage. As a result, the airport expects the National Grid to consider what steps they can take to prevent this incident from happening again.
Approximately 230,000 passengers use Heathrow Airport daily, equating to around 83 million passengers annually, making it one of the world's busiest airports. The incident serves as a reminder of the critical role electrical infrastructure plays in ensuring the smooth operation of such a vital hub. The investigation's findings will undoubtedly influence future safety protocols and regulations, aiming to prevent similar incidents from occurring in the future.
[1] Heathrow Airport. (2025). Heathrow Statement on the Report into the Power Outage in March 2025. Retrieved from https://www.heathrow.com/news/news-releases/2025/march/heathrow-statement-on-the-report-into-the-power-outage-in-march-2025 [2] Department for Business, Energy & Industrial Strategy. (2025). Statement by Ed Miliband on the Report into the Power Outage at Heathrow Airport. Retrieved from https://www.gov.uk/government/news/statement-by-ed-miliband-on-the-report-into-the-power-outage-at-heathrow-airport
[1] The report's findings indicate a need to address potential vulnerabilities in electrical infrastructure, emphasizing the importance of maintaining equipment and addressing environmental factors like moisture, which can cause equipment failure, short circuits, and fires.
[2] Although advanced technology and systems are in place to monitor moisture levels in electrical components, the report highlights the need for more robust maintenance practices and effective communication to ensure that identified risks are adequately addressed.
