Elsa Ruiz-Duran was startled awake early Tuesday morning by a loud explosion just outside her Old East Davis home.
Jumping quickly out of bed, she slipped on some flip-flops, grabbed her keys and headed for the door to see what had caused the noise, only to be greeted by yet a second loud and “terrifying” blast.
Once outside, she and several of her neighbors discovered that two PG&E transformers had exploded on the corner of Fifth and K streets, one below ground and one above, setting the overhead power line hanging above the neighborhood on fire.
According to the Fire Department, the two transformers and a utility pole also caught fire.
“Sparks were going up into the sky and (fire was) traveling across the (power) line,” Ruiz-Duran recalled Thursday. (PG&E) crew members called it a fireball.”
Davis firefighters, in addition to other emergency responders, were on the scene shortly after the explosions occurred just before 1 a.m. to monitor the situation until PG&E crews showed up. When the firefighters arrived at the 400 block of K Street, they discovered the two transformers were still ablaze.
“(The captain decided to) let the fires burn themselves out because there wasn’t a threat to anything” and because there was no risk of the fire spreading, according to Division Chief Bruce Fry. “The crew alerted PG&E and waited on scene until they arrived.”
PG&E crew members arrived soon after to fix the two transformers that had exploded and the other damaged equipment. The incident, meanwhile, left 3,561 residents without power for several hours.
“Everybody was terrified,” Ruiz-Duran added about the initial explosions and the fires.
That night, a PG&E worker told Ruiz-Duran that the explosions occurred due to the age of the equipment, which may have been installed as early as the 1970s.
However, PG&E officials say they actually haven’t yet identified what caused the explosions.
“I can’t speculate on that,” PG&E spokesman Paul Moreno said in response to the explanation given by Ruiz-Duran. “(The) ultimate cause has not been determined, it’s still under investigation.”
Moreno added that there could be many reasons why the equipment failed, such as adverse weather conditions, vehicle contact or even animal contact. Moreno said he didn’t know when the cause of the explosions would be determined.
To prevent malfunctions, PG&E crews perform routine maintenance and testing of all electrical equipment, Moreno said. However, PG&E officials were not able to readily say how often those inspections take place.
Fry, meanwhile, said the Fire Department’s protocol for handling electrical fires varies from case to case.
“Each scenario is different, so the basic response is to establish the parameters of the size of the incident and advise the residents,” sometimes instructing them to stay indoors until the situation has been resolved, he said. Fry added that electrical wire systems are designed to trip breakers when such incidents occur to halt the fire’s progression.
“At some point it’s going trip the breaker and isolate the source of the power,” thus preventing a fire from spreading down an entire block, Fry said. “You should not have a continuation of fire on a line.”
Rob Cain, the city’s urban forest manager, explained that PG&E’s vegetation management division is responsible for ensuring that there is a safe distance between power lines and trees to prevent any dangerous contact. He added that if residents have concerns about power lines near their homes, they should call PG&E directly.
Tuesday’s incident also isn’t the first in Davis in recent years where residents have questioned the utility and the age of its equipment.
In 2011, a dramatic number of gas leaks were discovered in the Stonegate subdivision in West Davis, prompting months of discourse between PG&E officials and residents over the safety of the gas lines running underneath their neighborhood.
PG&E admitted that the type of pipe transporting the gas, which in some places was installed several decades ago, was susceptible to brittleness and cracking. The utility later determined that the caps on the service line diversion points, called “service tees” — made from the same Aldyl-A pipe — were responsible for most of the 81 leaks they discovered.
The utility eventually replaced about 2,000 feet of transmission and service lines underneath the area in Stonegate that experienced the highest concentration of leaks.