PG&E aware of damage at Mission substation before blackout, SF Standard says

PG&E released a 70-page inquiry into the December blackout that left 120,000 residents in San Francisco, California without power, revealing that the utility giant was aware of damage at the Mission substation responsible for the incident but left damaged equipment in place, The San Francisco Standard’s Gabe Greschler reports. The investigation, conducted by the engineering firm Exponent, determined that inclement weather before the December 20 blackout spurred high humidity levels inside the company’s Mission substation and caused condensation buildup, resulting in a fire as well as the subsequent outage, the author notes.