Photovoltaic (PV) systems installed at homes, commercial buildings and industrial facilities can be mounted on pedestals, rooftops parking structures and the ground. Since I have spent so much time teaching people about PV systems, I
find it fascinating to see how they are installed.
I have spent most of my professional life as an electrician, electrical contractor, electrical instructor and National Electrical Code Panel member. I also spent half of the 20 years that I worked for Underwriters Laboratories teaching and testing people on how to install PV systems.
For about eight years, I was in charge of the UL photovoltaic accreditation and licensing program. I provided the first PV training and certification for Taiwan and Saudi Arabia. The training in Saudi Arabia concentrated on dwelling unit installations, and Taiwan’s were more commercial-based.
I travel extensively around the local Phoenix area, the United States and various other countries.
I have seen PV modules, panels or arrays mounted correctly and incorrectly. Some systems were extremely well done, some were marginal and some were just downright terrible. For the systems done correctly, I applaud the expertise and professionalism of the electricians and ECs. For the others, I hope future system installations improve and that safety is not compromised on those previously installed and those in the future.
Many installers do not realize that, where mounting PV modules on the roof of any building, provision must be made for firefighter access. This is critical for safety and quicker reaction time in an emergency situation. The location of modules to allow access on a roof is not covered in the 2023 NEC or in previous editions back to the 1984 NEC, when Article 690 on PV was first inserted.
Many installers do not realize that, where mounting PV modules on the roof of any building, provision must be made for firefighter access.
Articles 690 and 705 cover almost all of the requirements for safely installing a PV system. However, there are other safety issues not in the Code, and an installer must recognize and comply with them.
Requirements to keep in mind
Section 1205.2.1 in the 2018 International Fire Code and Section 11.12.3 in NFPA 1, Fire Code, recognize the location of PV module placement requirements for one- and two-dwelling homes and townhouses to allow rooftop access for firefighters. In NFPA 1, access pathways, setbacks and spacing requirements are required to provide emergency access, pathways to specific areas, smoke ventilation opportunity areas and emergency egress to and from the roof. The authority having jurisdiction can reduce or modify roof access based on fire department ventilation procedures or alternative methods that still ensure fire department access.
The modules must be mounted to provide not less than two 36-inch-wide access pathways on separate roof planes, from the gutter to the ridge of the roof. These access pathways shall be located in areas with minimal obstructions such as vent pipes, conduit or mechanical equipment, and at least one access must be toward the front of the building where the fire department will respond. The 36-inch path must be over the roof, and the measurement must not include the roof overhang.
Consider a 200-lb. fireman with an average 45 pounds of equipment without an oxygen tank, or 75 lbs. of equipment with the oxygen tank. I once saw a 300-lb. roofer fall through the sheathing on a dwelling unit roof and into an attic. Fortunately, he was not hurt.
For PV arrays occupying up to 33% of the plan view roof area, a minimum 18-inch setback must be provided on either side of a horizontal ridge. For PV arrays occupying more than 33% of the plan view roof area, a minimum 36-inch setback shall be provided on either side of a horizontal ridge. For one- and two-family dwellings with an automatic sprinkler system installed within the home in accordance with 22.214.171.124, for PV arrays occupying up to 66% of the plan view roof area, a minimum 18-inch setback must be provided on either side of a horizontal ridge. Finally, for PV arrays occupying more than 66% of the plan view roof area on sprinklered one- and two-family dwellings, a minimum 36-inch setback shall be provided on either side of a horizontal ridge.
I have seen many PV installations where there isn’t any access to the front or side edges of the dwelling due to improper locations of the modules. Check with your local AHJ before mounting the PV modules on the roof.
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