March fire near Heathrow Airport caused by substation maintenance failure

The fire that forced London’s Heathrow Airport to close in March this year, leaving thousands of passengers stranded, was caused by National Grid’s failure to maintain an electricity substation. An official report said so today. Britain’s energy regulator Ofgem immediately launched an investigation into the network operator based on the report.

The closure of Europe’s busiest airport cost airlines tens of millions of pounds and raised questions about the resilience of British infrastructure. Energy Secretary Ed Miliband described the report’s findings as “very concerning”.

The report is the result of an investigation into the incident at the end of March, carried out by electricity system operator National Energy System Operator. It separated from National Grid last year. Based on the report, Ofgem launched an investigation into National Grid Electricity Transmission, which owns and operates the high-voltage transmission network in England and Wales.

According to the report, the fire at Heathrow was caused by a “catastrophic failure” of one of the high-voltage bushings on a transformer at a National Grid Electricity Transmission substation. Moisture probably entered the bushing, causing an electrical fault and the subsequent transformer fire. The investigation found that National Grid’s monitoring systems failed to detect that no action had been taken over elevated moisture levels, which measurements had flagged as early as 2018.

National Grid said it has a comprehensive inspection and maintenance programme for its assets and has taken further measures since the fire.

Ofgem added that the review found the fire was caused by a technical fault that could have been prevented. It therefore plans to examine whether National Grid complied with the relevant legislation and licence conditions on the development and maintenance of the electricity network near Heathrow. It will also commission an independent audit of National Grid’s assets to establish whether this was an isolated incident or a systemic problem.

National Grid is involved in the transmission and distribution of electricity and natural gas. It is responsible for managing and operating critical energy network infrastructure in Britain. Its main task is to ensure the reliable and safe transmission of electricity and gas from generators to distributors and end users. National Grid also invests in developing and maintaining energy networks to ensure the stability and efficiency of energy supplies.