Despite the ongoing public safety power shutoff (PSPS) program, there is a possibility of a PG&E transmission line being responsible for sparking the Kincade Fire, and investigations are ongoing.
The Kincade Fire started in the area of the Geysers on Oct. 23. According to PG&E, the general vicinity of the fire had the distribution lines de-energized at approximately 3 p.m. on Oct. 23, however the high-voltage transmission lines were left intact.
In an Electrical Incident Report (EIR) filed with the California Public Utilities Commission on Oct. 24, PG&E stated “at approximately (9:20 p.m.) on Oct. 23, PG&E became aware of a Transmission level outage on the Geysers No. 9 Lakeville 230kV line when the line relayed and did not reclose. At approximately (7:30 a.m.) on Oct. 24, a responding PG&E Troubleman patrolling the Geysers No. 9 Lakeville 230 kV line observed that CalFire had taped off the area around the base of transmission tower 001/006. On site CalFire personnel brought to the Troubleman’s attention what appeared to be a broken jumper on the same tower.”
PG&E is required to report this incident under the Media Criterion utility statute, but notes that all the information is preliminary.
Transmission lines normally carry electricity at voltages over 69kV and are used to transmit power over long distances, usually from a central generating station to a main substation. A distribution line carries electricity at lower voltages, from 12kV to 44kV and is used to distribute power drawn from high voltage transmission systems to end-use customers.
Jumper wires are conducting wires that establish an electrical connection between two points in a circuit. In the case of high voltage transmission lines, since the towers themselves are built of a conducting material, the jumpers are used to move the power past each tower without electrifying it. The jump wires connect directly from the wires on one side of a tower to the wires on the other, creating an electrical connection that bypasses the tower.
The start of the fire was caught on a wildfire camera belonging to ALERTWildfire, an organization affiliated with the University of Nevada, Reno, UC San Diego and the University of Oregon. A massive spark and flare and then a quick expansion of fire can be seen on the video posted on YouTube. The camera is near Barham Avenue in Santa Rosa, and the video shows the ignition and explosive growth in the first 40 minutes of the incident.
The video can be seen here.
In a press conference on Oct. 24, CEO Bill Johnson stated that the tower in question is 34 years old and has been inspected four times in the past two years, including twice in 2019, once by climbing and once by drone. The only maintenance that had not been performed on the tower was a paint job.
“It appeared to have been in excellent condition, recently inspected,” he said.
According to Johnson, an internal investigation is ongoing and PG&E has not accepted responsibility for the fire.
“Filing the EIR does not tell us where the fire started so the fact we filed it does not tell us what caused the fire or where it started. CalFire, the experts in this, will draw their conclusion. We reported our findings to the regulator and are sharing them with you out of a sense of transparency.
“Now you may ask why was the transmission line on,” continued Johnson. “The transmission line was not among lines we de-energized in Sonoma County. The lines remained energized during the wind event consistent with our established protocols and procedures. In other words, they did not meet the conditions the we forecast for a transmission-level outage. We didn’t see the wind speeds in the forecast that we typically would see for those outages. At this point we still don’t know what happened. We did turn off the lower voltage distribution lines in the area because those did meet the criteria.”
CalFire incident commander Chief Mike Parkes was aware of the downed jumper line, but in a press conference on Oct. 24, he was careful to say that no cause for the fire had been determined yet.
“(We have not discussed the jumper) as it relates to any sort of a cause, we discussed it as infrastructure damage,” he said, adding, “We investigate any and all possibilities of all fires. Investigators have to rule out every possibility and just because an area is cordoned off doesn’t make it an area of interest, just an area they need to follow up with a little more detail.”
Mark Quinlan, PG&E incident commander for the Oct. 23 PSPS said that in general wind gust speeds requiring de-energizing of distribution lines is around 45 miles per hour, while the gust speed for transmission lines is closer to 55 miles per hour, and that those speeds are determined with an eye toward flying debris as much as anything.
“The lower voltage lines are more at risk of having debris contact and tree contact, because there are tighter lines of clearance and tighter rules about vegetation clearance around the asset,” Quinlan said. “The transmission system typically exists in large right-of-ways with a lot of clearance and regulations that exist that apply to how the right-of-ways can be cleared. Those are some of the things that frame up the playing field if you will, in terms of making a decision about wind activity and fuels.
“Keep in mind we want to de-energize as small an area as possible and be as surgical as we can in order to de-energize the right assets,” he continued. “Transmission lines are typically on steel and big and built to different design standards.”
Should PG&E decide to turn off transmission lines in the wake of the serious wind event forecasted for the weekend, the impacts could be widespread and significant, including places like the city of Healdsburg, who have their own distribution lines, but rely on PG&E transmission lines to bring the power to them.
This story will be updated as more information is made available.