A report by the National Energy System Operator (NESO) has found that the March 2025 fire at Heathrow Airport’s North Hyde electrical substation was caused by preventable faults and long-standing maintenance failures.
The incident, which resulted in more than 1,300 flight cancellations and power cuts to thousands of homes, has prompted Ofgem to launch a formal investigation into National Grid’s compliance with its safety obligations.
According to NESO, warnings about moisture in the high-voltage equipment were first raised in 2018, but necessary repairs were not carried out. The report also found that the site’s fire suppression system had been inoperative since 2022.
Energy Secretary Rachel Reeves said: “This was a serious failure in critical national infrastructure. It’s unacceptable that warnings were ignored and that a preventable incident caused such disruption to passengers, businesses, and residents.”
Ofgem confirmed it would be examining whether National Grid had breached its licence conditions, which could lead to enforcement action and fines.
The Heathrow incident has intensified calls for stricter oversight of the UK’s electricity network, with critics arguing that cost-cutting and slow investment in ageing infrastructure are putting public safety at risk.
Richard Black, senior associate at the Energy and Climate Intelligence Unit, commented: “This was an avoidable incident with severe consequences. It underlines the need for consistent investment in maintenance and robust safety systems.”
