A tripped breaker in Marathon probably due to weather spurred a power outage at 6:30 p.m. from Big Pine Key to Key West, Keys Energy Services spokesman Julio Barroso said. An automatic cascade of shutdowns along the system protects against power surges, he added. Most customers lost power for about 15 minutes; all were to be re-energized by 7:15 p.m., Barroso said.