<p>In our area of California, when the green grass dies and turns brown, the area under any type of array needs to be free of grass. An array could ignite a wildfire if the array were emit sparks. This is a very rare condition but it can happen to even the best design and module type.</p>
<p>There would not be any brush anywhere near an array. 10 feet from any point of the array makes sense but if there were a wildfire I would want alot more. 100 feet is typical for the zone around a home. That is what our AHJ wants to see in an inspection. We are in a very dangerous area for wildfires in the southern Sierra.</p>
<p>Brush does not count as grass. An array should survive a grass fire. Brush would be much more dangerous and must be kept clear as it is a much larger heat source than grass. I hope this is helpful.</p>
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<pre><strong><span style="font-size: small;">Dave Angelini Offgrid Solar
"we go where powerlines don't"
<a href="http://members.sti.net/offgridsolar/" target="_blank">http://members.sti.net/offgridsolar/</a>
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text 209 813 0060</span></strong></pre>
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<p>On Fri, 20 Mar 2020 17:06:01 -0600, Dan Fink <danbob88@gmail.com> wrote:</p>
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<div>Hello esteemed Wrenches; I am trying to clear this up for a client and his AHJ, which is also puzzled at how to interpret IFC 2018, Section 1204.4, which states:</div>
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<blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left: 1px solid #cccccc; padding-left: 1ex;">Setback requirements shall not apply to ground-mounted, free-standing photovoltaic arrays. A clear, brush-free area of 10 feet (3048 mm) shall be required for ground-mounted photovoltaic arrays.</blockquote>
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<div>I found one lone informational note in a white paper stating this was to prevent a burning PV array from igniting surrounding vegetation and the fire spreading.</div>
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<div>So, has anyone dealt with an AHJ on this before? Our questions are:</div>
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<li>What exactly is a "free-standing photovoltaic array" that is exempt? A pole mount? Couldn't burning debris from that ignite vegetation underneath?</li>
<li>What exactly does "A clear, brush-free area of 10 feet (3048 mm)" mean? "10 feet" is a linear measurement, not an area, that would be in square feet.</li>
<li>What is "brush"? Does grass count as brush?</li>
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<div>I would interpret this on the safe side as meaning that all vegetation under the PV array and out to a 10 foot perimeter should be cleared, except for pole-mount arrays (that exception makes no sense to me).</div>
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<div>I always recommend to clients that the area <em>under</em> the ground mount array should be pea gravel bordered by railroad ties, but out to 10 feet from the array edge seems excessive.</div>
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<div>Any input greatly appreciated!</div>
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