Pitched Roof Array Layout for Fire Code Compliance
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The latest fire code editions include requirements that could have far-reaching implications for residential PV installations.
In this article, I provide background on the two primary fire codes enforced in the US and the process that added PV system requirements to these codes. I focus specifically on fire code requirements that pertain to array layout on single- and two-unit residential dwellings. I discuss why these particular requirements, which may be new to you and your system designers, could have a negative impact on solar markets around the country. I then summarize some possible compliance strategies for companies that sell and install residential PV installations. Finally, I illustrate how proactive engagement with AHJs can help minimize the disruptive potential of these new requirements.
PV Systems in the Fire Codes
In July 2007, the California Department of Forestry and Fire Protection (CAL FIRE) established a task force consisting of fire service and solar industry stakeholders, as well as building code officials and codes and standards experts, to develop a set of PV system installation guidelines. This collaborative effort culminated in the April 2008 release of the Solar Photovoltaic Installation Guideline. (See Resources.)
While CAL FIRE originally developed the Guideline as an optional means of writing a local ordinance, its language was subsequently revised and incorporated into the 2012 editions of the two primary fire codes adopted and enforced in the US: the International Fire Code (IFC), published by the International Code Council, and the NFPA 1: Fire Code, published by the National Fire Protection Association, which also publishes NFPA 70, more commonly known as the National Electrical Code. As with the NEC, the issuing organization revises both fire codes every 3 years. While local regulatory agencies across the country vary in terms of which code or edition they enforce, the requirements related to PV systems are very similar in both the IFC and the NFPA 1.
Subsection 11.12 of NFPA 1 follows the format of the CAL FIRE Guideline and organizes requirements for photovoltaic systems into two main content areas: requirements for marking and requirements for access, pathways and smoke ventilation. Subsection 605.11 of the IFC includes these primary content areas, but also adds a third related to locations of dc conductors. The fire code content related to marking and wiring methods for PV power systems is generally harmonized with requirements in the 2014 NEC. AHJs and PV installers around the country should therefore be familiar with these requirements.
The goal of the CAL FIRE Guideline is to “increase public safety for all structures equipped with solar photovoltaic systems.” To achieve this principal objective, the Guideline places restrictions on rooftop PV installations to accommodate emergency response and fire suppression activities. The CAL FIRE Guideline is the only precedent for the PV array layout restrictions now found in the fire codes. These requirements may therefore be new to AHJs and PV system installers outside California and neighboring states such as Arizona and Oregon.
Bill Brooks is the principal at Brooks Engineering and a noted codes and standards expert. He was among the solar industry representatives who worked on the CAL FIRE Guideline, and he subsequently wrote the 2011 Solar America Board for Codes and Standards (Solar ABCs) report, “Understanding the CAL FIRE Solar Photovoltaic Installation Guideline.” (See Resources.) In this report, Brooks explains why revising the CAL FIRE Guideline for inclusion in the fire codes is significant: “This elevates the importance of the Guideline from a recommendation to a legally binding code, and makes a thorough grounding in the reasoning behind the Guideline even more important.”
Residential Array Layout Restrictions
The fire code requirements for PV arrays on steep-slope residential rooftops are in some ways more challenging to meet than those pertaining to low-slope commercial roofs. (See “Designing for Fire Code Compliance: Commercial Rooftop PV Arrays,” SolarPro magazine, August/September 2014.) Residential rooftops tend to be more varied in shape than commercial roofs. In addition, residential roofs are generally smaller and more space constrained than commercial roofs.