Fire Commission adopts bulletin allowing UL-tested rules for home battery spacing

The San Francisco Fire Commission on a unanimous vote adopted Fire Department Administrative Bulletin AB 5.12, changing how the department will interpret separation distances for residential energy storage systems (ESS).

The bulletin, presented by the fire marshal, permits applicants to submit UL 9540 test reports and corresponding manufacturer installation instructions to justify spacing that is less than the code's default three-foot separation. The fire marshal said the bulletin will accept the UL-tested spacing when provided and otherwise default to the existing three-foot separation in the code. "You can either use three feet or testing," the fire marshal said, and when both test results and installation instructions are present the department will use the larger distance listed.

Why it matters: the change aims to accommodate modern ESS designs and constrained installation space in San Francisco houses while maintaining fire-safety review. Proponents argued the revision will help homeowners and installers place more ESS units in tight spaces; opponents and some industry commenters urged a longer review.

Industry speakers who voiced concerns during public comment said more outreach and a formal rulemaking process were needed. Ben Davis of the California Solar & Storage Association said the clearance provisions in Section 3 "are not code interpretation; it is... new code and there is a formal rulemaking process for that that is being ignored here," and asked for more meetings with multiple manufacturers. Mark Balvasari of Enphase Energy told the commission he supported considering UL testing but asked for extended comment time to refine requirements. Janine Cotter, cofounder of Luminalt, said the bulletin in its current form "is going to continue San Francisco's practice of greatly restricting the ability of San Franciscans to install solar battery energy storage systems," and she asked the commission to consider a six-month trial period to measure impacts on installations in R3 occupancies.

Commissioners asked technical questions about test standards and installation clearances. The fire marshal cited examples from industry testing that showed some products could be safely installed with spacing down to six inches (with other manufacturers' instructions listing ten inches) and said the bulletin will require applicants to include UL test documentation and the manufacturer's installation instructions on submitted plans.

The commission adopted AB 5.12 by voice and roll-call vote; the motion to adopt was made by Vice President Armee Morgan and seconded by Commissioner Catherine Feinstein. The motion passed unanimously.

Next steps: The bulletin is now adopted as department guidance. Commissioners and staff said they may revisit the bulletin if industry practice or state code changes; several public commenters requested additional manufacturer engagement and a longer comment period before the requirements are fully relied upon for broad deployment.