<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">HI Jason,<div class=""><br class=""></div><div class="">My experience with fuses is that like breakers when you run them at or near their max rating they get hot and are prone to failure. </div><div class=""><br class=""></div><div class="">The added heat from environmental issues might be just enough to push it to failure. </div><div class=""><br class=""></div><div class="">Given the good performance data from enphase you might be able to correlate production watts and ambient temperatures to find a pattern.</div><div class=""><br class=""></div><div class="">Jay</div><div class=""><br class=""></div><div class="">PS I haven\u2019t researched enough to see if there are fuses rated for high heat and constant duty but that might be the answer if there are.</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Nov 19, 2020, at 3:25 PM, Jason Szumlanski <<a href="mailto:jason@floridasolardesigngroup.com" class="">jason@floridasolardesigngroup.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"></div><div dir="ltr" class=""><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Very interesting, Jay. The Bussman curve I just looked up is very similar. </div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br class=""></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">If that is the sole issue then replacing the disconnect alone with an HD version may not solve the problem. The better corrective action may be increasing the fuse rating and the wire size accordingly. However, since this is a 60A disconnect fused at 60A, that would require going to a 100A disconnect. I suppose increasing one wire size to #4 and using 80A fuses in a 100A disconnect may do the trick.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br class=""></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Now I'm conflicted. I don't know for certain whether direct sunlight is the primary issue since this happens on west walls under 18-inch eaves around 1:30pm (an hour after solar noon). My issue could still be a faulty or poorly designed switch.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br class=""></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br class=""></div><div class=""><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr" class=""><div dir="ltr" class=""><div dir="ltr" class=""><div dir="ltr" class=""><div dir="ltr" class=""><div dir="ltr" class=""><table border="0" cellpadding="0" cellspacing="0" style="font-family:"helvetica neue",helvetica,arial,sans-serif" class=""><tbody class=""><tr class=""><td rowspan="2" class=""><br class=""></td><td rowspan="2" class=""></td></tr></tbody></table><b class=""><div style="text-align:center" class=""><br class=""></div></b></div></div></div></div></div></div></div></div><br class=""></div><br class=""><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Nov 19, 2020 at 1:51 PM jay <<a href="mailto:jay.peltz@gmail.com" class="">jay.peltz@gmail.com</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class="">I looked up on the eaton site and found this information. Page 6, its a temperature derate curve, which I think is your problem.<div class=""><br class=""></div><div class="">In short, at 160F, for a slow blow fuse it is derated 20%. </div><div class="">At 176f its 25% derated.</div><div class=""><br class=""></div><div class="">I couldn\u2019t find any fuses that have a high temp rating.</div><div class=""><br class=""></div><div class="">jay</div><div class=""><br class=""></div><div class=""><a href="https://mailtrack.io/trace/link/474b2c27b2bb1ff895f6a23e345df0a69acb9530?url=https%3A%2F%2Fm.littelfuse.com%2F~%2Fmedia%2Felectrical%2Fapplication-notes%2Fpowr-gard-technical-application-guide.pdf&userId=1613865&signature=bac567fe7daf0198" target="_blank" class="">https://m.littelfuse.com/~/media/electrical/application-notes/powr-gard-technical-application-guide.pdf</a></div><div class=""><br class=""></div><div class=""><br class=""><div class=""><div class=""><br class=""><blockquote type="cite" class=""><div class="">On Nov 19, 2020, at 8:19 AM, Ken Schaal <<a href="mailto:Ken@commonwealthsolar.com" target="_blank" class="">Ken@commonwealthsolar.com</a>> wrote:</div><br class=""><div class=""><div dir="auto" class="">From my experience with reflective roofs galvanized quickly ages becoming less reflective! White is best aluminum paint next. <div dir="auto" class="">Ken Schaal</div><div dir="auto" class="">CommonWealth Solar</div></div><br class=""><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Nov 19, 2020, 9:17 AM frenergy <<a href="mailto:frenergy@psln.com" target="_blank" class="">frenergy@psln.com</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div class=""><p class=""> This is a very timely discussion for us also as we
have many Midnight MNPV6 discos in the sun. Though we're careful
about tightening wire landings, using contact cleaner for the
fuses and fuse holders, some installs seem to get hotter than
others. We just started making a very simple sheet metal heat
shield of sorts spaced away from the face of the disco for
ventilation which keeps direct sun off the "face" of the disco.
We don't paint this shield to give the galvanized surface a chance
to reflect the IR.<br class="">
</p><p class=""> Its a retro which we've covered the cost for to
prevent callbacks for blown (cooked?) fuses. I haven't done any
before and after temp checks but I know from a long history of
this kind of work that temps inside that disco will be
substantially lower. They haven't been out in the field long
enough to get any data.<br class="">
</p><p class="">Bill</p>
<pre cols="72" class="">Feather River Solar Electric
Bill Battagin, Owner
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849
CA Lic 874049
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<div class="">On 11/18/2020 5:13 PM, Ray wrote:<br class="">
</div>
<blockquote type="cite" class=""><p class="">What is the brand and model of the disconnect? Temp ratings of
the terminals? I've definitely had fuse holders not make good
contact with the fuses and burn the fuses at one end, instead of
in the middle. Have you looked at it with a Thermal imaging
camera when its operating to see if its hot on one end of the
fuse? <br class="">
</p><p class="">Second, depending on the temperature it would be hitting inside
the enclosure in the sun, you could be exceeding the rating of
the #6 conductor. Assuming terminals rated at 75C, then from
310.16, a #6 is rated 65 A, but derate for temperature of 114F
inside the enclosure gets you to .82 x 65 = 53.3, which is a bit
less than the 54.45 that Dave just calculated for continuous
duty. <br class="">
</p><p class="">What color is the disconnect painted? any chance of painting
it white?<br class="">
</p>
<pre cols="72" class="">Ray Walters
Remote Solar
303 505-8760</pre>
<div class="">On 11/18/20 4:16 PM, Dave Tedeyan
wrote:<br class="">
</div>
<blockquote type="cite" class="">
<div dir="ltr" class="">Jason,
<div class="">Bright sunny days, disconnect on the west side of house,
maybe in the sun? 43.56A * 1.25 for continuous duty =
54.45A. If these disconnects are also baking in the sun,
maybe the extra ambient heat is enough to push it over the
edge? Just a thought.</div>
<div class="">Cheers,</div>
<div class="">Dave<br clear="all" class="">
<div class="">
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<div class=""><b class=""><font face="tahoma,
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Tedeyan, PE</font></b></div>
<div class=""><font face="tahoma,
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<pre cols="72" class=""></pre>
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