Jason, Have you calculated your back-fed amapacity allowance to confirm it complies with the 120% busbar rule as per 705.12?
Best, Chris On Tue, Jan 21, 2020 at 12:40 PM August Goers <[email protected]> wrote: > Hi Jason - > > It certainly appears that there was some sort of surge or short. We've had > a few cases where microinverter branch circuit end termination caps were > left off or fell off and shorted out during rain storms. You might want to > double check that those are all in place. We've also had cases were > microinvers themselves developed internal shorts. This third comment is > only anecdotal - I've been in touch with a couple of other installers that > have had back-fed breaker issues specifically with Eaton brand breakers > burning up the bus stabs. Our company has had one unexplained issue where > the inverter output breaker bus stabs were burned up with Eaton breakers. I > have no idea whether the breakers were faulty or what, but thought I'd just > mention it in case there is a pattern. > > Best, August > Luminalt > > > On Tue, Jan 21, 2020 at 9:10 AM Jason Szumlanski < > [email protected]> wrote: > >> (System installed by another contractor...) >> >> 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: >> >> - 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. >> - 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. >> - A couple of weeks later, 1 of the 2 strings that was producing >> power quit doing so, but continued reporting data. >> - Customer discovered damage yesterday. >> - 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. >> >> 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. >> >> Jason Szumlanski >> Florida Solar Design Group >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: [email protected] >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://www.mail-archive.com/[email protected]/maillist.html >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> www.members.re-wrenches.org >> >> _______________________________________________ > List sponsored by Redwood Alliance > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/[email protected]/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > -- Chris Sparadeo C_802-369-4458 H_802-728-3059
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