News

Woodside: Officials still puzzled by no arcing when high-voltage wires fell on car

Maybe the wires weren't touching the car, fire chief says

When a Woodside eucalyptus tree fell on July 24 and took down a 60,000-volt power line that draped itself over a car and ignited several grass fires alongside Canada Road at Godetia Drive, why were there no arcs and sparks from the car when the young women in the car decided to get out?

The metal car would have been charged with 60,000 volts seeking the ground to complete a circuit. The only thing preventing a circuit are rubber tires acting as insulators. If a person inside the car opened a door and stepped on the ground while touching the car, that should have instantly created a path of least resistance between the voltage and the ground, sending a powerful current through her, causing serious injury.

"It's either dumb luck or the wires weren't touching the car," said Dan Ghiorso, fire chief of the Woodside Fire Protection District. Another possibility: the wires were already grounded on either side of the car, making an arc from the car less likely. "Maybe that was it," Chief Ghiorso added.

Had firefighters been there, they would have kept their distance from the car, Chief Ghiorso said, adding that he's seen high-voltage lines arc over a distance of 12 feet. "We would have told them to stay in the car until we got the wires secured."

"How did they get out of that car?" he said he asked representatives from Pacific Gas & Electric Corp. Their answer, he said: "We have no idea."

Chief Ghiorso, who was not on the scene, said he will be interviewing firefighters who were to better understand the location of the wires.

PG&E crews did arrive quickly, but complications with grounding the wires delayed the shutdown of the electricity, said Battalion Chief Rob Lindner of the Woodside district.

There were no reported injuries and the one-alarm fire, first called in at about 3:30 p.m., was contained within an hour and under control by about 8 p.m., Mr. Lindner said.

Fighting the fires were firefighters from the Woodside district, the Redwood City Fire Department and the San Mateo County Fire Department, as well as a wildland-response team from the California Department of Forestry and Fire Protection.

The Cal Fire group included five engine companies, two airplanes and a helicopter, with the helicopter doing most of the airborne firefighting, Mr. Lindner said. The helicopter dropped three or four loads of water, he said.

Traffic was snarled on northbound I-280 as the two lanes nearest the fire were closed. Parts of Canada Road were closed for several hours.

One fire, two fires

Woodside residents Denise and Millo Fenzi happened to be behind the lead car in the incident, and Mr. Fenzi made the 911 call, Ms. Fenzi told the Almanac.

"It was really something to watch," she said. "I just looked up and the tree was coming over Canada Road."

The driver ahead of her stopped and four young women got out and walked back to the Fenzis' car, Ms. Fenzi said. They all heard a loud bang and the fires started, she said.

"As we talked to the dispatcher, we watched the fires (start): one fire, two fires, three fires, four fires," she said.

Canada Road residents came out and fought the fire with hoses, she said.

Delayed response?

Ms. Fenzi said the firefighters took at least 10 minutes to arrive on the scene.

The tree blocked her passage home, so she turned around and got to I-280 north via the college campus, then to Edgewood Road and back down Canada to her home on the other side of the incident, where she loaded her three dogs into her vehicle. At that time, there was still no evidence of firefighters, she said.

"We live in a high fire danger area so how can it take 10 minutes?" she asked. "I don't know what to expect, but I know that's not right."

Fire Chief Dan Ghiorso said his engine company was on the scene six minutes and 45 seconds after hearing from dispatchers, well within the response-time standards.

A confluence of events may have contributed to the delay.

Ms. Fenzi said that during the 911 call, her husband had to repeatedly tell the dispatcher that a car had not collided with a tree and that the incident had not happened on the freeway.

"They were determined to make it a car accident," she said.

And it had been a busy few minutes, for dispatchers and Woodside firefighters, Chief Ghiorso said. Within the two-minute window of the 911 call about the Godetia Drive fire, there had been four others for the Woodside district: two vehicle accidents and two medical calls. FireDispatch.com also shows a separate report of smoke on I-280 at Woodside Road.

The fire district is investigating and has asked for recordings of the 911 calls, Chief Ghiorso said. The recordings may be available by Monday, Aug. 4, he said.

Comments

 +   Like this comment
Posted by Just a Neighbor
a resident of Woodside: Kings Mountain/Skyline
on Jul 31, 2014 at 1:15 pm

Rubber soled shoes?


 +   Like this comment
Posted by Science and Physics
a resident of Menlo Park: Downtown
on Jul 31, 2014 at 3:06 pm

If the passenger did not touch any metal parts while stepping on the ground then they would not be a conductor, (be electrocuted). The door handle is not necessarily electrically conductive.
If the wires are touching the ground already, as the report state, the car would not be electrically charged.
The statement that firefighters have seen high voltage arks of over 12 feet may be accurate, however, 60,000 volts is what spark plugs in your car use, even more. You don't see sparks jumping out from your engine. The only way to get an arc of that size is to ionize the air and make it more conductive. Web Link .
At sea level 30,000 volts will jump 1 cm. 60,000 volts will jump 2 cm.
Science seems to evade our culture.


 +   Like this comment
Posted by Joe
a resident of Menlo Park: Allied Arts/Stanford Park
on Jul 31, 2014 at 3:34 pm

A little further down in that explanation of arcing distances is this ...

"30000 V/cm is a guide, but you should never rely on that to keep you safe -- to put it another way, it'd be pretty stupid to stand just a few feet away from a charged 10kV capacitor bank on a humid day, and point at it: if you're lucky you'll just lose a finger. Play it safe, be very very careful, and ALWAYS have someone working with you or watching you, preferably someone who knows CPR."

They should have stayed in the car.


 +   Like this comment
Posted by April
a resident of another community
on Aug 6, 2014 at 10:38 am

God was protecting her.


 +   Like this comment
Posted by Alexander
a resident of another community
on Aug 6, 2014 at 1:32 pm

That's hilarious, April!


 +   Like this comment
Posted by Dean
a resident of another community
on Aug 7, 2014 at 6:52 am

No worries April,Alexander will know in his own time.


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