Heathrow substation fire cause remains unknown

Heathrow airport said an interim report into a power outage which caused its closure for most of a day “raises important questions”.

Transcript

00:00The National Energy System Operator published its initial report into the power outage at

00:07Heathrow Airport on Thursday after being commissioned by the Energy Secretary Ed Miliband.

00:14This report looks into the cause of the fire and the events that followed. However, the report

00:22clearly states that the root cause of the fire remains unknown. Yet it also seems to rule out

00:29anything of a suspicious nature. It does note how the Metropolitan Police confirmed on 25 March

00:36it had found no evidence to suggest that the incident was suspicious. In short, it remains

00:44a total mystery how this fire, which shut down one of the world's largest airports and left a part of

00:53London completely in the dark, actually begun. The report states that one of North Hyde substation's

01:02free supergrid transformers, devices which enable voltages to be stepped up or down so electricity

01:10can be efficiently distributed, became disconnected, known as tripping, at 11.21pm on March 20th.

01:19It was later confirmed to have caught fire. The operator said the flow of electricity to

01:25all four of Heathrow's passenger terminals was restarted by 10.56am on March 21st, with power

01:34restored to the wider Heathrow Airport Limited network by 2.23pm that day. Flights did, of course,

01:42not begin operating until around 6pm.