2023 NEC Updates to Rapid Shutdown Requirements
Rapid shutdown was introduced to the National Electrical Code (NEC) in the 2014 edition. Since then, numerous changes have been implemented to clarify the requirements. The 2023 version of the NEC included new changes that help clarify the intent and requirements for rapid shutdown (RSD) on structures like canopies, carports, and trellises that support PV arrays. The result is that the 2023 NEC explicitly excludes PV equipment and circuits installed on non-enclosed, detached structures from the requirements to control the conductors via rapid shutdown devices, 690.12 Exception No. 2.
Looking back one Code cycle, the charging language from the 2020 version of 690.12 states, “PV system circuits installed on or in buildings shall include a rapid shutdown function to reduce shock hazard for firefighters in accordance with 690.12(A) through (D).” This statement defines the intent of the Code section as reducing the shock hazard for firefighters, and becomes the basis of when RSD is required: locations where firefighter interaction would put those individuals at risk of shock. These locations include buildings where firefighters will be walking on the roof sections that hold the PV modules.
The NEC Code-Making Panel heard from the PV industry that jurisdictions were interpreting the 2020 language to include structures like solar canopies in the rapid shutdown requirement. This interpretation was based on the rapid shutdown requirement for PV circuits installed “on or in buildings” and the discrepancy between the NEC’s definition of a building and the definition found in building codes. This left some jurisdictions taking the most conservative approach and requiring rapid shutdown on nearly all PV installations.
The justification for the proposal to amend the 2023 Code stated, “The intent of this proposal is to clearly define that PV systems, installed in or on locations where firefighters will perform rooftop operations, require rapid shutdown (RSD) functions to allow firefighters to safely perform vertical ventilation and rescue operations. Basic firefighting methods are performed when there is an enclosed space below the PV system where the occupants may be working, living, or engaged in other similar actions. RSD was not envisioned for PV systems installed on solar carports, accessory structures, or ground mounted arrays since any heat, smoke, or occupants could egress through the open sides of the structure. …The defined area where RSD is required is an enclosed space, designed for human occupancy, where living, sleeping, eating, cooking, or working is performed and there are means of egress, light, and ventilation facilities.”
This change to exclude certain structures was approved by the Code-Making Panel and accompanied by a committee statement: “New Exception No. 2 is aligned with an existing exception to requirements for firefighter roof top access and pathways in the building and fire codes.”
Therefore, the NEC is clarifying the RSD requirement on non-enclosed structures to better align with preexisting fire code requirements. Furthermore, the NEC added another clarifying exception in 2023, 690.12(A) Exception, that conductors from non-enclosed structures that remain exterior to any buildings do not require RSD features. Such conductors require proper labeling per Article 690 and alert firefighters to potential hazards.
In accepting that proposal, the committee statement acknowledged that these installations have an inherent reduced risk of shock to firefighters and do not require RSD. The explanation offered here helps illustrate that the intention for RSD did not originally include circuits originating from non-enclosed structures such as carports. In addition, the current Code language provides clarity on the subject. It doesn’t change the installation methodology, and therefore, incorporation into current installations does not provide conflict or safety concerns.
Jurisdictions that are still working under 2020 are understandably reluctant to accept the 2023 clarifications. However, AHJs may have the ability to evaluate the change and implement the clarifying language without wholly adopting the entirety of NEC 2023. This installation method will ultimately provide more uniform installations and minimize the potential for unnecessary confusion if first responders encounter multiple configurations on non-enclosed, detached structures.
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