Solving problems in the
Wildland-Urban Interface

Joseph W. Mitchell, Ph.D.
Phone: 858 228 0089

Power Lines and Wildfire

14th annual International Association of Fire Safety Science Symposium

October 2023

I attended the 14th annual International Association of Fire Safety Science (IAFSS) symposium to present my analysis of California utility wildfire and risk models:

Analysis of utility wildfire risk assessments and mitigations in California


Fire Safety Science: Proceedings of the 14th International Symposium


The Conference was held in Tsukuba, Japan.

IMG 3010


The CPUC Risk-Based Decision-Making Framework

July 2023

As part of the S-MAP proceeding I was recently invited to give a presentation on tail risk and consequences for utility risk planning by the CPUC's Safety Policy Division. This is shown on the CPUC YouTube channel below.

Tail risk and event statistics for utility planning

About the S-MAP/RDF Proceeding

California statute requires utilities to include safety and reliability risk assessments and incorporate the findings into their funding requests.

The Risk-Based Decision-Making framework (CPUC proceeding R.20-07-013) - formerly known as S-MAP determines regulations and requirements for utility risk assessments. M-bar Technologies and Consulting have been contributing to these proceedings since 2014.




Reviewing Utility Wildfire Mitigation Plans - 2023

By California statute, electrical utilities must provide a complete Wildfire Mitigation Plan every three years, with yearly updates. The WMPs are submitted to the Office of Energy Infrastructure Safety (OEIS) and then to the California Public Utilities Commission (CPUC) for ratification.  The public is allowed to comment on these plans, which have come to comprise thousands of pages of the plans and supporting data and documents.

M-bar Technologies and Consulting has been reviewing these plans on behalf of MGRA since their inception in 2019.  While each iteration of the WMPs becomes more complete and sophisticated, there remain a number of key issues with the WMPs of the major California utilities that MGRA has identified. In the 2023 WMPs, the following issues were of particular concern:

  • Utility risk models generally do not adequately incorporate the influence of extreme wind events in triggering the outages that lead to wildfires.
  • As a consequence, utility models also overweight risk drivers unrelated to wind (such as animals, vehicles, balloons, or 3rd party).
  • Utility risk models that use wildfire spread simulations to calculate consequences artificially inflate risk nearer to the ignition point and underrepresent risk in remote high-wind areas.
  • Since PG&E proposed a 10,000 mile undergrounding program in 2021, all three utilities have introduced expanded undergrounding programs without adequately justifying the cost efficiency of undergrounding. While highly effective, undergrounding is the most expensive and there are other mitigations that have significantly higher cost efficiency.
  • New evidence from Southern California Edison's extensive deployment of covered conductor suggests that covered conductor may be more effective in preventing wildfires than the estimates utilities are using.
  • Combinations of covered conductor and new technologies (REFCL, Falling Conductor Protection, High-Impedance Fault detection) will further reduce potential for wildfire igntions.

 MGRA Comments on the 2023-2025 Wildfire Mitigation Plans of SDG&E, SCE, and PG&E


The October 2019 PG&E PSPS Website Failure

From October 8th to October 12th, 2019, PG&E planned its largest pre-emptive power shutoff event (PSPS) ever attempted by a utility in anticipation of an extreme Diablo wind event. As the event approached, performance of the PG&E website, a primary outlet for PSPS information, degraded and key components ultimately failed. As part of a CPUC proceeding investigating PG&E's October 2019 event, M-bar's expert prepared testimony and briefing for MGRA on the PG&E website failure. Our findings: PG&E's failure was at the root a lack of customer empathy. PG&E did not understand how its customers would use its website during a power shutoff event, and as a result under-estimated required capacity, failed to implement performance testing, and missed a key warning sign that could have helped it avoid the outage.


MGRA Testimony on the October 2019 PG&E Website Failure


MGRA Brief Regarding the October 2019 PG&E Website Failure

Utility Power Shutoff

Since our original involvement in defeating SDG&E’s proposed de-energization plan in 2008 we have provided technical support for MGRA's strong advocacy for requiring cost/benefit and risk/benefit analyses to determine thresholds for the risky wildfire prevention tool of utility power shutoff.
We remain involved at the California Public Utility Commission, advocating for the collection and analysis of customer harm data in order to properly determine utility “PSPS” thresholds.  We also advocate for aggressive remediation efforts to harden and protect utility infrastructure to reduce the need for power shutoff. 
2009 Whitepaper on De-Energization:
2019 CPUC Phase 2 Shutoff Proceeding
  • Quantification of customer and resident harm
  • Criteria for “reasonable” shutoff, including documented infrastructure damage
  • Requiring utilities to track predicted and measured wind speeds for all de-energized circuits