Age, heat may be behind underground electrical vault explosions in LA, engineer says
Heat may be behind electrical vault explosions
Two underground electrical vault incidents in the Los Angeles area have sent flames and concrete into the street in recent weeks. A forensic electrical engineer says aging infrastructure is likely the underlying factor, and extreme heat can make it worse
LOS ANGELES - As Southern California swelters through a heat wave, questions are growing about the underground electrical vaults buried beneath city streets.
Two recent incidents in Los Angeles sent flames or concrete into the road. A forensic engineer who spoke with Fox 11 says age and heat are a dangerous combination for underground electrical equipment.
What we know:
On Monday, Sept. 21, about 2 p.m., flames erupted from beneath the ground at West Westchester Parkway and Loyola Boulevard, near LAX. Video on social media shows the pavement lifting and fire shooting up as a car passes through the intersection.
Then, just before 4 a.m. Monday, a concrete electrical vault on Ventura Boulevard in Studio City was pushed up roughly 6 to 7 inches above the road, after what appears to have been a fire and explosion underneath. LAPD says as many as six cars hit the raised vault. No injuries were reported. One driver told FOX 11 he believes his car is totaled. LAPD and LADWP crews responded to the scene.
What they're saying:
Zacharias Macias, a licensed professional engineer and certified fire and explosion investigator with Macias Forensics, reviewed the video from the incident near LAX. He has not examined the vaults involved, but he said the flames suggest gas was involved.
Macias explained that the points where underground cables connect are a common failure point. Over time, heat and repeated heating and cooling can break down the insulation around the wires and release gases into the vault. An electrical arc can then ignite that gas.
"Age is definitely the underlying factor here," Macias said.
He said extreme heat can add to the problem. "When you have high heat in the area, you're going to have much more electrical power consumption," Macias said. "That's going to draw more current in those conductors, and that's going to accelerate any degradation that's already occurring."
Macias said the key question is whether the utility kept up with maintenance and inspections. "An investigation into their maintenance records and how they keep up their infrastructure is kind of the crux here," he said. He added that someone outside the utility should be part of that review.
Macias said these explosions are not common. As long as the utility stays on top of inspections and maintenance, he said there's no reason to panic. His advice for the public: "If you see smoke coming out from underground, or if you hear a popping or a crackling sound, stay away. Call 911."
What we don't know:
The cause of either incident has not been officially determined. It is not yet clear whether the driver in that video was hurt.
FOX 11 reached out to LADWP about both incidents and has not received a response.
The backstory:
Underground vault explosions aren't limited to Southern California. On Oct. 1, witnesses in San Francisco’s Financial District reported seeing flames shooting from vault lids and hearing loud booms.