I saw speculation that the use of "reconnectors' on the high voltage transmission lines may have played a role. These devices check to see if a line is really down by sending three pulses of current back through the downed line. Apparently that helps to prevent unnecessary blackouts. However, if the line is really down, and sitting on some brush, the test current can be enough to ignite the brush. PGE received some funds to remove these reconnectors, but they had not finished the job and they were apparently in service on the affected HV line.