HAVANA, Sept 18 (Reuters) – Cuba’s electrical ⁠grid ⁠suffered a total collapse on ⁠Friday, plunging the nation into darkness and leaving millions ​without power amid a US pressure campaign that has largely blocked oil from reaching ‌the Caribbean’s largest island. Friday’s collapse ‌was triggered by a failure in high-voltage transmission lines in central Cuba ⁠that occurred ⁠around 2 p.m. local time, authorities said. “Protocols are now in ​place to begin the gradual restoration of the system,” said Felix Estrada, an official with Cuba’s National Electrical Union (UNE). Power had returned to a handful of scattered neighborhoods in ​Havana by late evening, primarily around hospitals, but much of the city remained ⁠completely ⁠dark under cloudy skies ⁠and rain. The ​nationwide blackout, the latest of at least six partial or total grid collapses ​since January, hardly registered ⁠in a country accustomed to long hours, or even days, without power. Many exhausted residents of the capital Havana were already without power when the blackout hit. “Yesterday I’d gone without power for 24 hours. They turned the lights on …