Sometime before April 16, 2013, one or more people scouted the Pacific Gas and Electric Company’s high-voltage Metcalf substation off Highway 101 near San Jose, California. They went around the unmanned power station at a range of 40-60 yards, marking places from which the transformers’ cooling fins were clearly visible through the chain-link fence with piles of stones. According to a Wall Street Journal report last week, at about 1 a.m. on that April 16, someone cut the telephone lines going to the substation’s location in a manner calculated to be hard to repair. Within about another thirty minutes, shooters...