<div dir="ltr">Wrenches - What do you consider to be a safe ground impedance for a PV array equipment grounding conductor? NEC2011 250.53(A) says that if the impedance between the grounding <i>electrode</i> and earth is less than 25 ohms then no supplementary grounding electrode is needed, but I'm not clear on what that means for the ground impedance measurement within the array. For example, I am inspecting a ballasted landfill system (i.e. no penetrating the earth allowed - just a UFER at the equipment pad) where the ground impedance at the GEC is very low (<1 Ohm), but the array EGCs are showing ground impedances of between 500 and 1000 Ohms. The EGCs (#4) are connected to Cope cable trays, which are in turn connected to the inverter grounding bar via #4 bonding jumpers. The cable tray is grounded per manufacturer specs (large bonding jumpers at each joint), but the runs can be quite long (300'+) with many connections, though nothing appears to be loose. I intend to recommend that continuous conductors be installed to reduce array ground impedance, but any input on the issue would be very much appreciated.<div dir="ltr">
<div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><br><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><br><div><br></div><div><div><p class="MsoNormal"><span style="color:rgb(56,118,29)">For a brighter energy future,<br>
<br><br>Andrew Truitt <br>
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</div><div><p class="MsoNormal"><span style="color:rgb(56,118,29)">Principal<br>Truitt Renewable Energy </span><span style="color:rgb(56,118,29)">Consulting, LLC</span></p></div><div><p class="MsoNormal"><span style="color:rgb(56,118,29)"><a href="tel:%28202%29%20486-7507" value="+12024867507" target="_blank">(202) 486-7507</a></span></p>
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<span style="color:rgb(20,125,186)"><br></span>"Don't get me wrong: I love nuclear energy! It's just that I prefer fusion to fission. And it just so happens that there's an enormous fusion reactor safely banked a few million miles from us. It delivers more than we could ever use in just about 8 minutes. And it's wireless!"<br>
<br>~William McDonough</p><div><div><br></div></div></div>
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