The wildfire erupted on Oct. 30, 2019, and went on to burn 1,860 acres. At one point flames threatened to overrun the Ronald Reagan Presidential Library in Simi Valley.
"Fire investigators found that the fire started when an insulator attached to high-voltage power lines swung into a steel power pole," the Fire Department said in a statement. "The insulator showed damage consistent with grounding against the steel pole."
Three firefighters were injured while battling the Easy Fire, which damaged two structures.
Easy Fire cost Reagan Library nearly $500,000 in damage