The 9 August 2019 Great Britain Power Cut

Lightning struck a transmission line in eastern England on the afternoon of 9 August 2019. The strike itself was routine, the kind of event the grid is built to absorb, but a gas power station and an offshore wind farm both failed to ride through it as their equipment was supposed to, and disconnected within about two minutes of each other.

Britain's grid keeps enough reserve to cover the loss of its single largest generator, not two at once, so frequency fell and automatic systems cut power to protect the wider system. More than one million customers lost electricity for under an hour, but the outage stopped hundreds of trains that rely on trackside power, stranding passengers for hours longer.

Ofgem's investigation found both generators' protection settings did not meet the Grid Code, and fined the two companies involved, along with a network operator that reconnected customers without permission, a combined 10.5 million pounds.