Talking about "national" in the sense Spain (pop. 48M, 506,030 km²) is roughly equivalent to a few US states. A similarly (population/area) sized outage occurred a couple of decades ago:

* https://en.wikipedia.org/wiki/Northeast_blackout_of_2003

North America is organized in regional grids:

* https://en.wikipedia.org/wiki/North_American_power_transmiss...