How to survive a blackout

A massive power outage across Spain and Portugal left millions of people without electricity yesterday, and caused widespread disruption. As services return to normal in both countries today, many are left wondering how such a large and sudden blackout could happen – and what Britons can do to prepare in case it happens in the UK.

The loss of power – "the largest power cut in Europe’s recent history", said The Guardian – left almost 60 million people stranded on trains, stuck in lifts, log-jammed in streets without traffic lights, and unable to connect to phone or mobile networks for hours.

Investigations into the causes are still ongoing but it seems likely it was triggered by a "specific incident with an interconnector between France and Spain", Kristian Ruby of Eurelectric, the federation of the European electricity industry, told BBC Radio 4.

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Could a blackout like in Spain and Portugal happen in the UK?

"It's highly unlikely" but not impossible, Chris Owens of power-supplies manufacturer Riello UPS, told Metro. "Our power grid is reliable and robust. There's never been a complete failure of the UK's electricity network."

When Riello published its "Blackout Report" in 2019, it cited government assessments that the risk of a UK grid shutdown within five years was "one in 200". So, while that's not likely, "the odds are considerably shorter than winning the lottery", Owens told the paper.

What can cause major outages?

There are several factors that can contribute to a massive power cut. Interconnector failures – the suspected cause of Spain's and Portugal's outage – are one example, and atmospheric conditions are another. Extreme weather can take down parts of the power grid – as it did in the UK's "Great Storm" of 1987, when 120mph winds battered Britain and damaged infrastructure. And solar flares are also a risk: these eruptions from the sun can create geomagnetic storms that interfere with power, navigation and communication systems.

Cyber attacks are also a growing concern. The Spanish government has said it does not believe Monday's power outage was due to a cyber attack, although an investigation into that possibility has been opened. There have been widespread recent worries that cyber attacks could take down power grids across Europe, as happened in 2015 when Russian hackers caused a blackout in Kyiv by infecting energy companies with malware that switched off substations and emergency power stations.

Is the UK prepared?

Asked whether the power cut on the continent had triggered a fear that British infrastructure could be affected in the same way, Home Secretary Yvette Cooper told Sky News that the UK has a "continued approach" to "resilience" and "security issues"

Yet Sarah Schubert, chair of the Institute of Civil Protection and Emergency Management, warned that the UK is becoming "ever more fragile" by relying so much on computer technology. Speaking to The i Paper in 2023, she advised people to "be prepared" and have "some degree of self-sufficiency for at least 72 hours" in case of an emergency.

What should I do right now to be ready?

Here's what you should do to prepare for a major power outage or emergency, according to a government action list and advice from the National Grid.

• Stock up on spare batteries, charged power banks, and a wind-up torch at home.
• Keep a wind-up radio at home, with a written list of local and national station frequencies, so that you are able to get official information via emergency broadcasts if needed.
• Make sure you have blankets, and plenty of bottled water and non-perishable food, such as cans of fruit and vegetables or ready-to-eat tinned meat.
• Find out your power load/block letter. The power grid is broken up into load blocks and grid operators could schedule emergency power cuts on a rotating basis. This letter may be on your electricity bill or you can find it at powercut10.com.
• Download or print out maps in case you do not have access to the internet or live map-based mobile apps.
• Ensure any essential medical equipment that you rely on is charged regularly, with a battery back-up for emergencies. If you have extra communication or safety needs, make sure you're on your electricity supplier's Priority Services Register.

What should I do during a blackout?

• Switch off appliances to avoid power-surge damage when the power returns.
• Keep your fridge and freezer doors closed to protect your food. According to the Food Standards Agency (FSA), your fridge will keep food safe for up to four hours during a power outage, while a full freezer will hold a safe temperature for approximately 48 hours if full, and for 24 hours, if half full, as long as the door is kept shut.
• Leave one light on, so you'll know when power returns.
• Try to avoid using candles if possible, as these can pose a fire risk.