Puerto Rico's grid struggles since 2017 hurricanes.. Outage caused by protection system failure and vegetation on lines.. Nearly half of the homes and businesses in Puerto Rico that receive electricity from the commonwealth's main utility were still without power on Thursday, a day after a widespread blackout struck the island, Luma Energy said in a statement. Hospitals, airports and prisons were among the structures still out. ... On New Year's Eve last year an underground power line was the most recent failure that led to island-wide ... some customers who have had service restored may experience temporary system outages throughout...