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Vermont committee hears safety warnings on plug‑in solar devices; UL presents new UL 3700 standard
Summary
Lawmakers on the House Energy and Digital Infrastructure committee heard union and safety experts raise concerns that plug‑in photovoltaic devices could overload older wiring and bypass protective devices unless they meet technical safeguards such as UL 3700 certification or are limited to dedicated circuits.
Representative Kathleen James convened the House Energy and Digital Infrastructure committee on March 19 to continue consideration of S.202, a bill addressing portable plug‑in photovoltaic (PIPV) devices intended to expand access to small‑scale solar.
The committee heard from Jeffrey Wat, business manager of the International Brotherhood of Electrical Workers (IBEW) Local 300, who said his members and the utilities that represent their employers are worried that current plug‑in devices can “back feed” electricity into household wiring and the grid in ways that existing breakers and protective devices were not designed to handle. "If it's UL listed, hey, I got no complaint," Wat said, urging that safety certification be part of any path forward. He added that "safety goes out the window when money comes into play," arguing enforcement and consumer behavior remain concerns even if standards exist.
Wat outlined several concrete hazards: PIPV units can inject current downstream of a home's circuit breakers so overloads may not be detected by the panel; ground‑fault circuit interrupters (GFCIs) can be impaired by bidirectional current; and older wiring may overheat or degrade over time when additional current is injected. He told the committee that requiring a dedicated circuit for a PIPV device would eliminate many overload risks but acknowledged that installing a dedicated receptacle can add time and cost — he estimated "a couple hundred" dollars in a typical house — and may be a barrier for renters and some owners.
UL Solutions presented technical findings and a new product‑level safety standard. Ken Boyce, vice president of engineering for UL Solutions, described why UL developed UL 3700 after reviewing PIPV systems in jurisdictions such as Utah and Virginia. "UL 3700 is a comprehensive set of technical requirements specifically designed to address PIPV safety concerns," Boyce said, summarizing the standard's focus on system design, verified compatibility with bidirectional GFCIs, touch‑safety measures, and mechanical and environmental durability tests.
Boyce explained that UL 3700 offers multiple pathways to mitigate hazards, including design controls that prevent unsafe backfeeding, verified protection for circuits that accept injected current, and, as one option, requiring that the device connect only to a dedicated circuit. He told lawmakers UL 3700 had been finalized and that UL was working with manufacturers; as of the hearing he said UL had not yet issued certifications under the new standard but expected that to change.
Committee members pressed both witnesses on practical enforcement and consumer implications. Members asked who would be responsible for compliance — manufacturers, sellers, installers or buyers — and whether European experience with plug‑in units translates to U.S. wiring and breaker standards; witnesses noted European systems and code differ materially from U.S. practice. The committee also discussed landlord/tenant implications, referencing Virginia law that allows lower‑wattage plug‑in systems and includes renter notification provisions; witnesses suggested landlords could pay to install a permanent dedicated receptacle that would remain with the property to reduce cost barriers for renters.
No formal votes were taken. Committee staff will follow up with UL on distributing the UL 3700 white paper and technical summary, and legal staff will review the Utah and Virginia approaches for comparison. The committee expects to hear further testimony from utilities and fire‑safety officials in upcoming sessions.
What this means: Testimony at the hearing focused on balancing consumer access to small‑scale solar with electrical safety in older housing stock and legacy U.S. wiring practices. The two principal technical options discussed were (1) requiring PIPV products to meet a product safety certification such as UL 3700 and (2) limiting installations to a dedicated circuit or panel‑level interconnection that preserves overcurrent and ground‑fault protection.
