Expert tells House panel UL 3700 already covers safety for plug‑in solar; committee weighs referencing standard in S202

Representative Kathleen James convened the House Energy and Digital Infrastructure committee on April 3 to take testimony on S202, a bill to set safety requirements for plug‑in solar devices that can be plugged into household outlets.

Bill Brooks, a registered professional engineer and principal at Brooks Engineering, told the committee that the UL 3700 standard — which he described as an "umbrella standard" — addresses the main safety concerns committee members had raised, including utility interconnection, touch safety, and compatibility with household wiring and protective devices. "I would classify UL3700 ... as an umbrella standard," Brooks said, adding that the standard brings together testing and performance requirements from related documents.

Brooks explained that UL 3700 sits in a family of standards that includes UL 1741 and references interconnection and grid‑support test procedures derived from IEEE 1547. He told members the standard has been issued in standard form and that products can be certified to it, though "to my knowledge there are no products currently certified to that standard," with certification typically taking about one to six months.

Committee members pressed Brooks on specific technical items they had heard in prior testimony: whether a dedicated circuit is required; whether a specialized plug or birectional ground‑fault circuit interrupter (GFCI) is necessary; and how devices will avoid overloading existing house wiring. Brooks answered that power control systems (PCS) — a technology that monitors loads and limits injected power into a branch circuit — are central to the safety approach in 3700 and that requiring a dedicated circuit in statute could unduly limit the technology. "Power control systems are absolutely [what] deal with overcurrent," he said.

On the question of plugs, Brooks said the initial version of 3700 requires a specialized plug to ensure touch safety, but that testing pathways could allow a standard three‑prong NEMA 15A plug to be certified if accompanying protections are demonstrated. He compared the brief energized state of a plugged device to commonly used uninterruptible power supplies, noting those products remain energized for about one second when unplugged and are generally treated as safe when certified and used per instructions.

Members also asked about installation, permanent mounting and older housing stock. Brooks said UL 3700 expects manufacturers to provide installation instructions and that mounting hardware and structural testing are addressed via UL 2703 when a product is intended to be permanently attached. He said the National Electrical Code (NEC) and installation requirements account for older wiring and that in some cases the device's internal protections (for example, built‑in GFCI or PCS) can address compatibility with legacy systems.

Several members noted that their draft bill uses the phrase "UL Solutions or an equivalent nationally recognized testing laboratory"; Brooks said that while other labs could test to the UL standard, UL is regularly the organization that develops solar safety standards and that including the "or equivalent" language is a common statutory drafting choice to avoid naming a single private actor.

The committee did not take a vote during the hearing. Members said they would consider referencing UL 3700 in S202 rather than enumerating detailed technical requirements in statute, so the rules can evolve with standards and technology. The hearing concluded after committee members thanked Brooks for his testimony.