Designing for Fire Code Compliance

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Commercial Rooftop PV Arrays
  • Designing for Fire Code Compliance
    Designing for Fire Code Compliance
  • Perimeter access
    The fire codes require a clear perimeter around PV arrays on commercial rooftops to allow fire crews to access the roof from any direction, stage equipment and maneuver around one another. This...
  • Pathways
    Firefighters can use centerline axis and straight-line pathways to move across a roof, to access skylights for vertical ventilation or as a means of emergency egress.
  • AHJ exceptions
    According to the CAL FIRE Guideline, local jurisdictions are empowered to reduce access, pathway or ventilation requirements when certain criteria are met, such as when there are “adequate...
  • Exit strategy
    When designing large rooftop PV arrays, it is important to leave room for routing PV power circuits off the roof and to verify that no obstructions are on the side of the building or at ground level.
  • Rooftop step-over
    If an AHJ determines that the combined width of cable trays or conduits crossing fire service pathways or access areas constitutes an obstruction, you may need to install a ramp, bridge or step-over...
  • Don’t miss the BOS
    When laying out commercial PV arrays that will use low-profile mounting systems, you must account for dc aggregation system components and ensure that they do not encroach on the access, pathway and...
  • Elevated mounting system
    One benefit of mounting modules on elevated racks is that it leaves room underneath the array to accommodate BOS components such as raceways and dc combiners.
  • Designing for Fire Code Compliance
  • Perimeter access
  • Pathways
  • AHJ exceptions
  • Exit strategy
  • Rooftop step-over
  • Don’t miss the BOS
  • Elevated mounting system

In a first, the most recent fire code editions include requirements specific to PV systems. Meeting these requirements provides fire service personnel with access to the roof and room to conduct emergency fire suppression activities.

The rooftops of commercial buildings provide some of the best locations for PV systems. Picture the roof of a commercial building that does not require climate control systems or HVAC equipment, such as a distribution warehouse. This expansive, relatively flat roof with few obstructions is an ideal open space for a PV installation. However, to comply with current fire code requirements, PV system designers still need to ensure that the layout of the array provides fire service personnel with perimeter roof access, pathways within the array and smoke ventilation opportunities.

In this article, we review the evolution of fire code requirements related to PV systems. We then focus on those requirements that pertain to access, pathways and smoke ventilation for PV systems on commercial buildings and explain the rationale behind these regulations. We also review the process of complying with these fire code requirements and suggest useful design strategies to avoid permitting and inspection problems.

Evolution of Fire Code Requirements

The current fire code requirements for PV systems began as a set of recommendations known as the Solar Photovoltaic Installation Guideline, which CAL FIRE—the California Department of Forestry and Protection—developed in partnership with “interested local fire officials, building officials and [solar] industry representatives” (see Resources). CAL FIRE’s Office of the State Fire Marshal initiated the development of these guidelines in August 2007 “with safety as the primary objective.”

Unlike ac electrical systems, conventional PV systems include dc circuits that remain energized even when the PV inverter is disconnected from the utility grid. Recognizing the unique nature of these hazards and the burgeoning growth of PV installations, CAL FIRE determined that regulations were needed to guarantee that the design of rooftop PV installations would facilitate fire suppression operations and ensure firefighter safety while still meeting the needs of the solar industry.

The final draft of the Solar Photovoltaic Installation Guideline, published in April 2008, is known informally as the CAL FIRE Guideline. In the 2011 Solar America Board for Codes and Standards (Solar ABCs) report, “Understanding the CAL FIRE Solar Photovoltaic Installation Guideline,” Bill Brooks summarizes the intent and scope of the CAL FIRE recommendations: “The purpose of the Guideline is to help firefighters identify PV systems, protect electrical wiring and safely access roofs for vertical ventilation operations during fire suppression activities. The Guideline includes guidance about clearly marking conduit and equipment; access, pathways and ventilation; and the location of dc conductors in both residential and commercial buildings” (see Resources).

The CAL FIRE Guideline does not have the force of law. Rather, it is a “suggested means of writing a local ordinance.” As such, the Guideline describes the process whereby an individual governing body in California—such as a city or county—could convert the wording in the Guideline into a legally enforceable code. However, the Guideline also recognizes that AHJs have broad powers to amend the language. On one hand, AHJs are empowered to “establish more restrictive” provisions based on “climatic, topographic, or geological conditions.” On the other hand, AHJs “may approve alternative means of compliance based on their authority.” This provision allows individual AHJs to adapt to and permit evolving products, designs, technologies and installation methods while still implementing necessary safety considerations.

From guideline to code. While CAL FIRE originally wrote the Guideline as a recommendation for local ordinances, other agencies have since codified the design and installation practices it describes. In his Solar ABCs report, Brooks explains: “In May 2010, the International Code Council (ICC) approved a revised version of the Guideline for inclusion in the 2012 version of the International Fire Code (IFC). 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.”

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