Placing power lines underground is an expensive way to reduce the risk of fire

San Diego Gas & Electric introduced the idea of ​​proactively cutting power after the witch's fire in 2007, which sparked resistance from state control authorities said Wara. But since then, he said, the utility has refined the technique and created "micro-grids" within its system, so that a shutdown can only affect 10,000 customers, not 100,000.