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<p>Almost every meltdown I've looked at was not due to lightning,
but heat from a high resistance connection. A lug not torqued can
cause surrounding plastic to melt. If the wrong breakers are used
with the buss bar, they might snap on and work, but not be able to
take the current over time. Coupled with high humidity, you can
start getting corrosion going which further increases the
resistance. Eventually, if its gets bad enough, the resistance
can cause glowing red hot metal, and attached insulator plastic
starts melting. <br>
</p>
<p>Its also possible that someone knocked a wire or breaker loose?
Or possibly shorted the buss doing something wrong, corrected the
error, but didn't realize the buss had been damaged. Lots of
guessing, but that's how you figure it out. <br>
</p>
<p>If it was lightning, there would be lots of related damage:
Enphase inverters and other electronics cooked. <br>
</p>
<pre class="moz-signature" cols="72">Ray Walters
Remote Solar
303 505-8760</pre>
<div class="moz-cite-prefix">On 1/21/20 12:51 PM, Jerry Shafer
wrote:<br>
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cite="mid:CAMUFgmW2Rp4MOPkxESvD00kGtEt0fs3cFKQ1VPRCsEUgcdpzuQ@mail.gmail.com">
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<div dir="auto">Wrenches
<div dir="auto">Cant tell anymore but l had a buss failure due
to water getting on buss and pealing the tin off the buss and
the aluminum base will light up real quick.</div>
<div dir="auto">Jerry</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Jan 21, 2020, 9:10 AM
Jason Szumlanski <<a
href="mailto:jason@floridasolardesigngroup.com"
moz-do-not-send="true">jason@floridasolardesigngroup.com</a>>
wrote:<br>
</div>
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<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif">(System
installed by another contractor...)</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif"><br>
</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif">I have been
tasked with assisting in the investigation of damage in a
subpanel used to combine inverter output circuits (5
strings of microinverters). There appears to be no damage
to conductors or other system components. It looks like
the damage started at the stabs of the bus bar where the
breakers connect. Picture attached. Here are a few clues:</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif">
<ul>
<li>Monitoring indicates that damage occurred overnight
a few weeks ago. That night we had rain as a winter
front came through Florida, possibly lightning. The
prior day everything was fine.</li>
<li>The next morning, only 2 of 5 strings started
producing power, but 4 of 5 strings were reporting
data to the Envoy. The two strings that were reporting
but not producing power reported 0Vac and Voc on the
DC side of the microinverters. </li>
<li>A couple of weeks later, 1 of the 2 strings that was
producing power quit doing so, but continued reporting
data.</li>
<li>Customer discovered damage yesterday.</li>
<li>About a week before the initial damage apparently
manifested itself, another contractor installed a
whole house generator transfer switch on the line side
of the PV interconnection. The generator has never
been run (there is not even a LP fuel source on site
yet). I pointed out that the solar interconnection,
which was previously on the supply side, would need to
be moved to the supply side of the generator transfer
switch's main breaker before operation. During the
transfer switch installation, the contractor also
switched line 1 and line 2, but that shouldn't
really matter, except for Enphase consumption
monitoring, which was messed up by the swapping of the
lines.</li>
</ul>
<div>So I'm looking for ideas. I'm wondering if the OCPD
would be a likely place for lightning damage to manifest
itself. I can't visually detect any other damage
anywhere else. I can't imagine that the transfer switch
installation would have anything to do with it, but the
timing is interesting. Other than replacing the subpanel
and OCPD and firing it back up (no pun intended), I'm
not sure how to approach further investigation.</div>
<div><br>
</div>
<div>Jason Szumlanski</div>
<div>Florida Solar Design Group</div>
</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif"><br>
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