What the Iberian blackout taught us: eight lessons for any household

What happened on 28 April 2025

Updated 30 October 2026

At 12:33 Central European time on a Monday, the power systems of mainland Spain and Portugal went down completely. AP reported that Spain lost 15 gigawatts, about 60% of its demand, in five seconds. A small corner of south-west France flickered. ENTSO-E, the body that links Europe's grid operators, later called it the most severe blackout on the European power system in more than 20 years.

Within minutes, trains stopped between stations and the metro stopped in its tunnels; emergency workers rescued around 35,000 passengers, and many spent the night in stations wrapped in Red Cross blankets. AP reported that mobile communications were disrupted and cash machines shut down across the peninsula.

Power came back through the evening and night. By 11am on Tuesday, Red Eléctrica said Spain's system was working normally, and Portugal's REN said all 6.4 million of its customers were reconnected.

It was not harmless. AP, citing the Spanish agency EFE, reported five deaths under investigation in Spain in the first days. Three older members of one family in Taboadela, a small town in Galicia, were found dead at home, where a generator had been running an oxygen machine; emergency workers found a high concentration of carbon monoxide in the house. A woman in Valencia died when her oxygen machine failed. Another died in a fire started by a candle in Madrid.

What caused it

For months there was speculation. The answer, when it came, was dull and technical. ENTSO-E's expert panel published its final report on 20 March 2026 and found no single cause, but "a combination of many interacting factors": oscillations on the grid, gaps in voltage and reactive power control, different voltage-control practices, and power stations in Spain cutting output or disconnecting quickly. Voltage rose fast, more generators tripped off to protect themselves, and the cascade took down the whole system.

For a household, the cause matters less than the lesson: a modern grid can fail all at once, for reasons nobody sees coming, and nobody can tell you on the day how long it will last.

Eight lessons for your home

1. The phone is not a plan

Mobile communications were disrupted across the peninsula, and when phone masts lose power their backup batteries don't last long. Agree now, on paper: one family member outside the area that everyone calls or texts, and one place to meet if you can't reach each other. A school, a relative's flat, the café on the corner. Write it in each person's wallet.

2. A battery radio is how you hear what's going on

With phones and internet gone, radio was the only news. In Portugal, the price-comparison site KuantoKusta reported demand for battery radios up by about 4,600% straight after the blackout, and power banks by about 1,700%. Buy before, not after. A cheap AM/FM radio on AA batteries does the job, with your national broadcaster's frequency taped on the back.

3. Cash, in small notes

Cash machines shut down, and card terminals need power and a network too. A shop that stays open in a blackout can only take cash, and soon runs out of change. Keep a modest amount in coins and small notes at home. The Dutch government suggests €70 per adult and €30 per child.

4. Water stops in tall buildings

Flats above a few storeys rely on electric pumps to push water up. When the power goes, the taps on the upper floors can run dry within hours, and the lift stops too, so every litre has to be carried up the stairs. Fill the bath and every pot the moment the power goes, and keep stored water in containers you can lift: 5 and 10 litre bottles, not one big drum. The water guide has the sums.

5. Nothing that burns goes indoors

The Galicia family is the hardest lesson. A generator, a barbecue, a camping stove or a charcoal heater makes carbon monoxide, which has no colour and no smell, and kills people asleep in their beds. The CDC's rule: a generator goes outside, more than 6 metres (20 feet) from any window, door or vent, never in a house, basement or garage even with the doors open. Put a battery carbon monoxide alarm near the bedrooms. More in generator safety and carbon monoxide.

6. Torch first, candle last

The Madrid death was a candle. In a blackout, candles come out of drawers all over a city at once. Use torches, headlamps and battery lanterns first. If you light a candle, stand it in a dish of water or a jar, 30 cm from anything that burns, and blow it out before anyone sleeps.

7. If someone depends on a machine, plan for it now

Oxygen concentrators, home ventilators, dialysis, powered beds, insulin in the fridge. Ask the supplier today how long the backup battery lasts and what to do if it runs out, and keep the hospital's number on paper. In the UK, join the Priority Services Register; elsewhere, ask your energy company whether it keeps a list of medical-needs customers. The Be Ready guide explains it.

8. Be ready to be stuck away from home

The blackout started at lunchtime, on a working day. Tens of thousands were on trains and metros; many more were at work, miles from home, with no phone and no transport. Keep a small kit in your work bag: a power bank, a little cash, a bottle of water, a snack, and the family meeting plan on paper. Comfortable shoes in the office drawer are not a bad idea either.

Not the only one

A grid-wide blackout is rare. Long local ones are not. In January 2026, a deliberate fire on a cable bridge in south-west Berlin cut power to about 45,000 households and 2,200 businesses in winter, heating included, and it took around four days to restore everyone. Storms take out power for days somewhere in Europe every year.

That is why the EU now asks every household to be able to manage for at least 72 hours, and why the UK launched its own campaign in October 2026. The EU 72-hour kit guide has the list.