LONDON: A fire that caused a hugely disruptive shutdown at Heathrow airport in March was caused by the failure of a component at an electricity substation that had not been properly maintained, Britain’s National Energy System Operator said on Wednesday (Jul 2).
Britain’s energy regulator Ofgem launched an official enforcement investigation into National Grid Electricity Transmission based on the report’s findings, the watchdog said in a separate statement.
The closure of Heathrow, the busiest airport in Europe, on Mar 21 cost airlines tens of millions of pounds and stranded thousands of passengers. It also raised questions about the resilience of Britain’s infrastructure.
“This review has seen evidence that a catastrophic failure on one of the transformer’s high voltage bushings at National Grid Electricity Transmission’s 275kV substation caused the transformer to catch fire,” the report by the National Energy System Operator said.
“This was most likely caused by moisture entering the bushing, causing an electrical fault.”
National Grid controls in place were not effective and failed to identify that action had not been taken in relation to an elevated moisture reading in 2018, the report said, adding that the issue went unaddressed.
Energy minister Ed Miliband said the report was “deeply concerning”.
National Grid did not immediately respond to a request for comment.