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UC Berkeley analysis: fast‑trip settings sharply cut utility‑ignited fires, changing undergrounding calculus
Summary
University of California, Berkeley researchers told the Assembly committee that enhanced power system safety settings (fast trip) sharply reduced ignitions in PG&E territory and are more cost‑effective per avoided structure than enhanced vegetation management; undergrounding still eliminates risk on targeted circuits but is costlier.
A UC Berkeley researcher told the Assembly Committee on Utilities and Energy that operational changes to how distribution equipment trips have dramatically reduced ignition risk in recent years and altered the cost‑benefit outlook for mass undergrounding.
Duncan Callaway, professor and chair of the Energy and Resources Group at the University of California, Berkeley, said his team's models show enhanced power system safety settings, commonly called "fast trip," reduced ignitions by about 82% on circuits where they were applied. "These fast trip settings are tremendously cost effective," Callaway said, adding that undergrounding still "completely or nearly completely eliminates risk on the circuits that do get undergrounded." He emphasized that the new operational measures make the marginal value of additional undergrounding smaller than it was before those innovations were deployed.
Why it matters: Undergrounding distribution lines is widely viewed as the most effective way to eliminate wildfire ignitions tied to overhead infrastructure, but the panel heard that it costs roughly $3–4 million per mile for distribution undergrounding and requires long lead times and extensive coordination. Callaway said operational measures such as fast trip and covered conductor can achieve large risk reductions at a materially lower cost per avoided structure.
Callaway's team compared dollar‑per‑avoided‑structure metrics for interventions: enhanced vegetation management (lower effectiveness per dollar in his models), fast trip (high cost‑effectiveness), and undergrounding (very effective but expensive). He noted that fast trip's emergence in 2021–2022 substantially reduced the expected number of structures burned in the modeled period and recommended a stepwise approach to capital‑intensive undergrounding given ongoing innovation.
Limitations: Callaway and several committee members noted that his data run through 2023 and that very recent transmission incidents — including the Eaton Canyon fire under investigation in 2025 — could change the analysis if those events prove to be caused by transmission equipment. "If the Eaton Fire costs turn out to be the result of SCE infrastructure failure," Assemblymember Hart asked, "would that change the trends or conclusions?" Callaway replied he would wait for the cause determination and that his work focuses on long‑term probabilistic averages rather than single events.
What the committee asked for: Members requested more data sharing and continuous evaluation so regulators and utilities can re‑optimize the mix of operational and capital investments as technologies evolve.
