New Details Emerge After Massive Tuolumne and Calaveras Counties Power Outage

Scene of the explosion in Chinese Camp—CAL Fire TCU photo

Tuolumne County, CA – New details are being released after an explosion at the Pacific Ultrapower biomass energy plant in Chinese Camp left nearly 30,000 PG&E customers without electricity yesterday.

As we reported here on Friday (1/9/26), the areas without electricity stretched from Strawberry to Sonora, Columbia, Jamestown, Copperopolis, and Groveland. Initially, the Tuolumne County Fire Department (TCFD) reported a lithium-ion battery explosion at that plant. CAL Fire Battalion Chief Jeff Cox tells Central Sierra Broadcasting, “It was actually another private business’s transformer outside of the plant that created a power surge, impacting PG&E equipment, causing the outage.”

The transformer next to Pacific Ultrapower belongs to Engie, an energy transition firm whose website states that its mission is to expedite the transition to a carbon-neutral economy. The proximity to the Chinese Camp plant caused confusion, according to Cox, who added, “There was no fire at that plant and no injuries to workers, who were all accounted for.”

PG&E confirmed that the explosion caused the outage and that its equipment suffered no substantial damage.  The plant shut down, and Cox advised that he does not know when it will reopen. He disclosed, “What triggered the transformer’s explosion has yet to be determined.”