The sweeping power outage that hit Spain and Portugal this week has raised questions about the electricity grid in a region not normally known for blackouts

Luis Ibáñez Jiménez was driving on a highway in east Madrid when Spain lost power. “Suddenly, there were no traffic lights,” the resident of the capital told CNN. Cars piled up, and nobody had right of way.

A widespread power outage disrupted life across Spain and Portugal, briefly extending into parts of France, leaving millions without electricity.