<p>London: The fire that caused a hugely disruptive shutdown at Heathrow airport in March was likely caused by the failure of a component at an electricity substation, Britain's National Energy System Operator said in a report on the incident on Wednesday.</p><p>"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.</p><p>"This was most likely caused by moisture entering the bushing, causing an electrical fault."</p>.Explained | How did a fire leave Heathrow Airport in darkness, with insufficient backup?
<p>London: The fire that caused a hugely disruptive shutdown at Heathrow airport in March was likely caused by the failure of a component at an electricity substation, Britain's National Energy System Operator said in a report on the incident on Wednesday.</p><p>"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.</p><p>"This was most likely caused by moisture entering the bushing, causing an electrical fault."</p>.Explained | How did a fire leave Heathrow Airport in darkness, with insufficient backup?