Butte County filed suit against PG&E on Tuesday, alleging that the company's failure to respond to extreme weather conditions in the hours before November's Camp Fire played a central role in sparking the catastrophe.
The Nov. 8 fire killed 86 people and destroyed nearly 14,000 homes in and around the town of Paradise, a community the suit describes as "effectively eradicated" by the blaze.
The suit joins dozens of others filed against PG&E in the weeks since the blaze erupted, and like the others alleges that a long history of negligent operations by the utility led to the blaze. Cal Fire investigators are still studying the fire's cause.
The day after the Camp Fire sprang to life, PG&E told state regulators that it had experienced an unexplained outage on the 115-kilovolt Caribou-Palermo transmission line at about the same time and place the blaze was first reported. That initial report indicated an aerial patrol later on the fire's first day found damage to a transmission tower at the ignition site.
Subsequent reports from the company have said further inspections revealed that a broken hook on a transmission tower may have allowed an electrically charged piece of equipment to swing free, causing an electrical arc. A second possible ignition site, about a mile away from the first, involved a broken PG&E pole and downed power lines.