Shares of Rosemead-based Edison International fell 12 percent Monday after its utility subsidiary Southern California Edison announced that a problem with its transmission grid occurred near the origin point of the massive Woolsey Fire still burning in Los Angeles and Ventura counties.

Also on Nov. 12, the San Jose Mercury-News reported that the California Public Utilities Commission has launched probes into both Southern California Edison and Pacific Gas & Electric – a unit of San Francisco-based PG&E Corp. – to assess whether the utilities complied with existing rules and regulations for their equipment in the current fire zones.

According to the Mercury-News and other press reports, Southern California Edison reported to the PUC that on the afternoon of Nov. 8 – the day the Woolsey Fire started – a circuit in its power transmission grid at its Chatsworth substation recorded a “disturbance” two minutes before the first report of fire came in.

If the circuit disruption is determined to have sparked the Woolsey blaze, Edison could be liable for all or most of the damages caused by the fire thanks to a peculiar state inverse condemnation policy and recent court and regulatory decisions. State wildfire legislation enacted in September – but not taking effect until Jan. 1 – will change this. After Jan. 1, Edison’s shareholder liability for damages resulting from the wildfires its equipment is found to have triggered will depend on findings from the PUC as to whether the utility was following existing rules and regulations regarding equipment maintenance and fire prevention.

As of Tuesday morning, the Woolsey Fire had burned more than 96,300 acres in the eastern portion of Ventura County and the western portion of Los Angeles County and was 35 percent contained. It has destroyed or damaged at least 370 structures. More than 200,000 people were evacuated during the fire, and mandatory evacuations remain for Malibu, Topanga Canyon and parts of Westlake Village and Calabasas.

Shares of Edison International (EIX) plunged 12 percent Monday but rose Tuesday, posting a gain of $1.97, or 3.7 percent, to close at $55.53 on the New York Stock Exchange.