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Many Factors to Consider When Providing Access to Roofs with a Photovoltaic System Installed

Blog Post created by vboutin Employee on Jul 24, 2020

The use of renewable energy is on the rise and one popular source is photovoltaics (PV). Section 11.12 in the 2018 Edition of NFPA 1, Fire Code covers everything related to PV installations from marking to rapid shutdown to accessways. There are a number of things to consider when installing a PV system on the roof of a building, but perhaps the most popular topic for questions has to do with the required pathways. Providing proper pathways is extremely important because firefighters need access to the roof for firefighting operations. Often, there is confusion about the size and location of the required pathways. The pathway requirements are different for PV arrays installed on one- and two-family dwellings and townhouses than they are for all other buildings. Here, we will focus on the pathway requirements for all those other buildings.

 

There are essentially three types of pathways that are required. The first type ensures firefighters will be able to get on the roof and are often called perimeter pathways. The second type of pathway ensures that firefighters can move around the roof once they have gained access. These are referred to as “other pathways” in the Code. The final type of pathways provide access to areas for ventilation. The size of the perimeter pathways is going to depend on the building size. For any building with a length or width greater than 250 ft (76.2 m), a minimum 6 ft (1829 mm) pathway is required on all sides. If both the length and width are 250 ft (76.2 m) or less, then the pathway is only required to be a minimum of 4 ft (1219 mm). The images below show what these pathways look like in plain view.

The “other pathways” required by the Code allow firefighters to move around the roof as needed. These types of pathways are required under three different conditions. The first is to provide straight line access to ventilation hatches and/or roof standpipes. Wherever ventilation hatches and standpipes are located a pathway of at least 48 in (1219 mm) must be provided.  A 48 in (1219 mm) pathway around all roof access hatches must also be provided. In addition to the pathway around the roof access hatch, at least one 48 in pathway must be provided from the roof access hatch to the roof edge or parapet. The last type in this group is to ensure that there is a pathway every 150 ft (46 m). The 150 ft distance cannot be exceeded in either the length or the width of the building. This essentially limits the PV array to a maximum size of 150 ft by 150 ft (46 m by 46 m).

 

The final category of pathways required are for smoke ventilation. The third type of pathway listed in the “other pathway” paragraph, which limits the array size to 150 ft by 150 ft (46 m by 46 m), will be used to provide ventilation options. The width of this pathway will depend on what, if any, type of ventilation options If there aren’t any ventilation options provided (such as skylights or smoke and heat vents) then the pathway must provide a minimum 96 in. (2438 mm) between array sections. If there are existing roof skylights or dropout smoke and heat vents are provided on at least one side    of the pathway, then the pathway must only be a minimum of 48 in (1219 mm) wide. A 48 in. pathway is also permitted where there are 48 in. by 96 in. (1219 mm by 2438 mm) venting cutout options every 20 ft (6096 mm). The last type of required pathway for venting is where nongravity-operated smoke and heat vents are provided. For those, a 48 in. (1219 mm) pathway must be provided around the vent.

 

 

 

It is not uncommon to see PV systems connected to energy storage systems (ESS). This allows the energy generated from the PV system to be stored and used later on when it is needed. For more information on ESS take a look here and at NFPA 855. There are many components to ensuring a PV system is installed correctly. Here we’ve focused on the pathway requirements for buildings other than one- and two-family dwellings and townhouses. Other requirements such as marking requirements and requirements for rapid shutdown can all be found in NFPA 1, The Fire Code, Section 11.12.

 

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