<div dir="ltr"><div class="gmail_default" style="font-family:times new roman,serif;font-size:large">Hello, breakers are thermal-magnetic the current heats the breaker; if the current is high enough for long enough, a solder pot inside melts; this current and excessive heat causes other breakers to open Are you sure the string current is less than 80% of the breaker rating and the wire connecting to the breaker is ampacity 120 percent of the current? I have seen several of these events when the cabinet is in the sun or in other hot locations. Also, excessive breakers in a panel board can cause heat build-up and premature breaker tripping. If a breaker trips from heat several times, the bus bar clip can soften or distort, this can damage the bus. </div><div class="gmail_default" style="font-family:times new roman,serif;font-size:large">I hope this has some value.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Aug 4, 2022 at 1:12 PM Jason Szumlanski via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">I have a commercial 208 volt job where four of 11 fully populated strings of IQ7A had breakers that were tripped as reported by the client. They were able to reset two of them. They also reported that the two they were not able to reset we're very hot. The other two were warm. By the time I got to the site, all four breakers had permanently failed. <div dir="auto"><br></div><div dir="auto">Once I got replacements, I was able to install them and they turned on without any faults. I gave it about 15 minutes and then put my infrared camera on it. To my surprise, the breaker immediately above two of the failed breakers and across from the other two failed breakers was clearly hot. I'm thinking this might have been the bad breaker all along causing the heat issue on the bus bar which made adjacent breakers fail. But this hot breaker did not fail.</div><div dir="auto"><br></div><div dir="auto">Does this seem like a plausible scenario, and if so, any ideas on what might have caused it? All of the breaker bolts were tight, but a couple were not torqued to spec. I just find it strange that one breaker that didn't fail would cause other adjacent breakers to heat up enough to fail.</div><div dir="auto"><br></div><div dir="auto">Flir image attached. This was after I replaced the four failed breakers.</div><div dir="auto"><br></div><div dir="auto">Jason Szumlanski</div><div dir="auto">Florida Solar Design Group </div></div>
_______________________________________________<br>
List sponsored by Redwood Alliance<br>
<br>
Pay optional member dues here: <a href="http://re-wrenches.org" rel="noreferrer" target="_blank">http://re-wrenches.org</a><br>
<br>
List Address: <a href="mailto:RE-wrenches@lists.re-wrenches.org" target="_blank">RE-wrenches@lists.re-wrenches.org</a><br>
<br>
Change listserver email address & settings:<br>
<a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" rel="noreferrer" target="_blank">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a><br>
<br>
There are two list archives for searching. When one doesn't work, try the other:<br>
<a href="https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/" rel="noreferrer" target="_blank">https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/</a><br>
<a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org" rel="noreferrer" target="_blank">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><br>
<br>
List rules & etiquette:<br>
<a href="http://www.re-wrenches.org/etiquette.htm" rel="noreferrer" target="_blank">http://www.re-wrenches.org/etiquette.htm</a><br>
<br>
Check out or update participant bios:<br>
<a href="http://www.members.re-wrenches.org" rel="noreferrer" target="_blank">http://www.members.re-wrenches.org</a><br>
<br>
</blockquote></div>