Thanks for sharing, Jason. That's an excellent cautionary tale... On Wed, Jan 22, 2020 at 2:58 PM Jason Szumlanski < ja...@floridasolardesigngroup.com> wrote:
> I discovered the issue I believe, so I thought I'd update all of you who > gave me ideas on what to look for (thank you). > > And this is something that I stress the importance of all the time... > > The branch circuit pairs were not properly paired up! All of the L1 > conductors went to L1 on the bus and all of the L2 to L2. However, for > example, circuit 1 L1 and circuit 2 L2 were on a single 2-pole breaker. And > circuit 2 L1 and circuit 1 L2 were on another breaker. Everything worked > because it was electrically connected to the right bus bar. However, when > there was a previous fault one of the breakers probably didn't trip when it > should have as a result of the improper pairings. It was reset a few times > and just kept heating up and heating up. > > This isn't conclusive, but it sure makes sense. It wasn't fun tracking > this down with 5 strings and 5 junction boxes on the roof, but once we > started continuity testing and finding strange results, it became clear. > > Jason Szumlanski > > > > On Tue, Jan 21, 2020 at 12:10 PM Jason Szumlanski < > ja...@floridasolardesigngroup.com> 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: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > -- Blake Gleason, PE | Employee Owner Director of Innovation and Technical Excellence O: 510-845-2997 x128 C: 510-867-5878 1035 Folger Ave. Berkeley, CA 94710 www.sunlightandpower.com License #326203 <https://bcorporation.net/> <https://www.amicussolar.com/> <https://calssa.org/>
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