UK power cut: What happened, why it was so bad and who is to blame for outage that left 1 million in the dark?

Incident a ‘wake-up call’ to energy industry

Large power cuts such as the one which hit swathes of the UK on Friday can be dangerous events for those affected.

In addition to inconveniencing those trying to use public transport and creating “apocalyptic” scenes on high streets, vital hospital systems were affected in Ipswich after a back-up generator failed.

Here’s everything we know about the outage so far.

What happened?

On Friday afternoon around a million homes and businesses suffered power cuts.

Traffic lights were knocked out, flights grounded and passengers stuck on halted trains for hours, with one commuter describing the atmosphere at Clapham Junction as “like witnessing something out of an apocalyptic film”.

“All the traffic lights were down, but there were no police present, which meant it was dangerous to cross – cars weren’t stopping either,” said Harriet Jackson, 26. ”Nothing was open and there was hardly any phone signal.”

Euston and Kings Cross train stations in London were brought to a standstill with rush hour commuters forced to use the torches on their mobile phones to exit the London Underground, which was plunged into darkness in some areas.

Train signals lost power across the south, in Bristol, Newport and Eastbourne, while passengers travelling from Edinburgh to London were stuck on a train for an extra eight hours.

Around 300,000 UK Power Networks customers were affected in London and the south east, and Western Power Distribution said around 500,000 people were affected in the Midlands, south west and Wales. Power was restored to them all shortly after 6pm.

Northern Powergrid, which serves Yorkshire and the North East, said 110,000 of its customers lost power, while at least 26,000 people were without power in the North West of England, Electricity North West said.

Why was it so bad?

The “incredibly rare event” appears to have been triggered after two power stations disconnected from the grid “near simultaneously”, said a senior official at National Grid, which owns the electricity transmission system in England and Wales.

A gas-generated plant Little Barford, Bedfordshire, is thought to have disconnected first at 4:58pm, followed by Hornsea, a wind farm in the North Sea, just two minutes later.

The loss of these two generators led the system to automatically cut off power to some parts of the country in order to “keep the rest of the system safe”.

The last time something similar had happened was in 2008, National Grid’s operations director Duncan Burt told the BBC.

Although power was restored to most parts of the country by 6:30pm, the shortage posed dangerous problems.

At Ipswich Hospital, a backup generator failed, and outpatients, X-rays and scans were all affected.

No patients were harmed but an urgent investigation has been launched into the failure, East Suffolk and North Essex NHS Trust chief executive, Nick Hulme, told the BBC.

Who is to blame?

Mr Burt ruled out the possibility the outage had been caused by a cyber attack, and said the National Grid was “very confident” there was no malicious intent.

He also dismissed suggestions a failure linked to wind power was responsible for the power cut, saying it had “nothing” to do with changes in wind speed or the variability of wind.

Professor Tim Green, co-director of the Energy Futures Laboratory, Imperial College London, agreed. He said: “This event does not appear to be due to wind generation reducing owing to reduced wind speed. If that were the case there’d be reduction across many wind farms in [the] same area.”

However, questions were raised over why the system had cut power to sensitive areas like hospitals and airports.

Mr Burt said the shut-off was automatic, but admitted it was “something we will want to look at really closely”.

Will there be recriminations?

Energy market regulator Ofgem has demanded “an urgent detailed report from National Grid so we can understand what went wrong and decide what further steps need to be taken”.

Ofgem has said these steps could include enforcement action and a fine, the Financial Times reported.

The regulator has the power to fine companies up to 10 per cent of their annual turnover.

Could it happen again?

The outage was ”wake-up call” to the energy industry, Schneider Electric ​energy analyst David Hunter said.

“It raises questions in that although this was a very rare event, it was very significant,” he told the BBC’s Today programme.

While the odds for similar occurrences in the near future remain relatively low, the National Grid’s Mr Burt admitted it could take months to work through the lessons of Friday’s failure.

“We have, in the UK, one of the most reliable networks in the world,” he said.

Additional reporting by agencies