<div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif">We are 100% on the same page. That is the technique we use and the argument I make. In a large proportion of cases we have modules directly above the existing premises grounding electrode, or otherwise where an additional grounding electrode would be "as close as practicable" to a location within 6 feet.</div><div class="gmail_default" style="font-family:verdana,sans-serif"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif">A 25MW plant presumably has several distinct structures on which it is mounted. I can see the rationale for a GEC and electrode for each structure in that scenario. But a single building with various roof faces is technically a single mechanically integrated structure on which PV modules are mounted. </div><br><br><div id="WISESTAMP_SIG_gmail_session" href="http://WISESTAMP_SIG_gmail_session"><div style="font-size:13px;font-family:Verdana,Arial,Helvetica,sans-serif"><div style="margin:0 0 8px 0"><p style="margin:0"><span><span>Jason Szumlanski</span></span></p><p style="margin:0"><span><span></span></span></p><div class="gmail_default" style="font-family:verdana,sans-serif;display:inline">Fafco Solar</div><br><p></p><div style="clear:both"></div></div><img src="https://wisestamp.appspot.com/pixview.gif?p=chrome&v=3.50.0&t=1412016437320&u=d0c775731865b324" width="1" height="1"></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Sep 29, 2014 at 2:19 PM, Ray Walters <span dir="ltr"><<a href="mailto:ray@solarray.com" target="_blank">ray@solarray.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>Definitely could use some
clarification. The 690 definition of an array says "mechanically
integrated", which sort of implies each roof plane is its own
array.<br>
However in terms of actual PV design terminology, each PV system
has only one array which may consist of many subarrays. Even a 25
MW plant has Only One array!<br>
So once again, NEC is inventing its own language that is not
consistent with actual terminology in use for over 30 years.
(Ugh)<br>
My call is that you would bond each subarray to each other with
#6, and then bring down a single GEC. Multiple GECs sounds very
silly, but damn that NEC language.<br>
I would argue that "mechanically integrated" means they are all
bolted down to the same building (one support structure)<br>
What other electrical system would require multiple GECs for an
installation on a single building ?<br>
<br>
Good Luck,<br>
<pre cols="72">R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
<a href="tel:303%20505-8760" value="+13035058760" target="_blank">303 505-8760</a></pre><div><div class="h5">
On 9/29/2014 6:21 AM, Jason Szumlanski wrote:<br>
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<blockquote type="cite"><div><div class="h5">
<div dir="ltr">
<div style="font-family:verdana,sans-serif">The definition of Array
in 690.2 is ambiguous. Figure 690.1(A) seems to indicate that
groups of modules on different roof surfaces could be
considered a single array. The textual definition itself could
be construed either way. We have successfully argued that an
entire roof mounted system with modules on different roofs
constitutes a single array. Therefore, if the additional
grounding electrode required by 690.47(D) qualifies for
Exception 2, it is not required. However, our "favorite"
jurisdiction has just interpreted it differently, requiring a
separate electrode and electrode conductor for each roof
surface... and there are a lot of roof surfaces on this
particular job. Complying will not be fun or cheap.</div>
<div style="font-family:verdana,sans-serif"><br>
</div>
<div style="font-family:verdana,sans-serif">How is your
jurisdiction interpreting this?</div>
<div><br>
</div>
<div><br>
</div>
<div style="font-family:verdana,sans-serif">Related note: Figure
690.1(A) would effectively make each module in a microinverter
based system a distinct array. The figure seems to imply that
all modules that form a PV Output Circuit are a single array.
Each module is a complete PV Output Circuit in a microinverter
based system. It's strange that the textual definition is
concerned with mechanical assemblies, but the figure refers to
electrical configuration in defining Array. In fact, in the
text an Array is defined as components forming "a
direct-current power-producing unit." In a microinverter-based
system, how can any group of modules be considered an array
given that definition? </div>
<br>
<br>
<div href="http://WISESTAMP_SIG_gmail_session">
<div style="font-size:13px;font-family:Verdana,Arial,Helvetica,sans-serif">
<div style="margin:0 0 8px 0">
<p style="margin:0"><span><span>Jason Szumlanski</span></span></p>
<p style="margin:0"><span><span></span></span></p>
<div style="font-family:verdana,sans-serif;display:inline">Fafco
Solar</div>
<br>
</div>
</div>
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