On July 17, 2015 The lights go out in Washington as the Nats’ first home game after the All-Star break is interrupted with the Dodgers leading, 2 – 1, in the 4th inning when a bank of lights on the third base side of the field at Nationals Park go out. Stadium personnel manage to turn them back on after a one hour, 22 minute delay, play resumes for 9 minutes, and the lights go out again. This time, 40 minutes are needed to restore power, but it lasts just 12 minutes. The game is finally suspended at 10:42 pm in the 5th inning, the Nationals having in the meantime taken the lead on a two-run homer by Danny Espinosa during the second brief resumption of play.
Source
Baseball Reference July 17