San Diego, CA, USA — State officials have confirmed that recent brushfires may have been sparked by a commonly-used guy-wire system used to keep power poles straight in the air, confirming the suspicions of an insurance company investigator, it was reported on Saturday.
Evidence of burning on guy wires, and blackened power poles, shows that electricity had arced from live power lines and travelled down the guy wires, said investigators from the California Public Utilities Commission.
The guy wires in question were not insulated, and could have sparked fires as the poles and wires were buffeted by winds that approached hurricane force last fall. No proven ignition of any fire from guy wire arcing has been found, however, the San Diego Union-Tribune reported.
“We’re looking at those black marks to see why they were caused,” said PUC safety program manager Raffy Stepanian. “The black spots seem to be (the result of) arcing.”
The guy wires are used across the country, and come down from power poles at 45-degree angles to offset the weight and wind load of power lines. The PUC opened an investigation into the way San Diego Gas & Electric guy wires are used after charring was first noticed by Edward Clark, a Huntington Beach insurance company consultant who examined areas near fire ignition points.
Three fires last October — the Witch Creek, Rice Canyon and Guejito blazes — were sparked by power lines. Clark suspects that one of them, the Witch Creek fire, was sparked by a faulty guy wire.
That single blaze claimed at least 500 houses and 100 commercial buildings, and scorched 145,000 acres of land.
SDG&E said it is assisting the investigation and has not seen the PUC findings. The utility said its particular guy-wire installation policy has been used for 75 years and is used nationwide.
The guy wires being investigated are not insulated. Many utility poles in southern California have glass insulators on guy wires to isolate them electrically and prevent arcing, officials have said.
State officials are still investigating whether a guywire and power pole collapse in Malibu Canyon last fall sparked the Canyon Fire, the second of three major fires that hit the Malibu coast last year.