Heathrow power outage was due to equipment issue known for years

A massive power outage that crippled operations at Heathrow Airport in March resulted from the failure of critical equipment at a nearby electrical substation, according to an official report on the incident.

The analysis from the National Energy System Operator found that a buildup of moisture inside the substation’s “bushing” — insulators that keep high-voltage environments operating safely — led to a fire.

National Grid Plc’s own guidance had acknowledged back in 2018 that such an issue could cause an “imminent fault,” though preventative steps weren’t taken, according to NESO.

UK energy regulator Ofgem said Wednesday it’s opened an investigation into National Grid following the publication of NESO’s review.

The company has faced calls to strengthen the resilience of its infrastructure following the March 21 fire and power cut, which brought travel to a standstill for hundreds of thousands of passengers.

National Grid said in a statement that it supported the recommendations in the report and would cooperate closely with Ofgem’s probe.