HI Dan,
All the big three have the same wiring diagrams with a positive buss and then breakers going out from there. And yes there is no main disco for the DC branches. But if your point was that the fuse could/will blow and then you have the PV/wind connected to the inverter and could over volt it, then yes I agree. This was actually a problem that happened to a friend using some rapid shutdown with a trip/breaker at the battery. It shut down the battery but the system continued to work as the PV had enough energy to feed the inverter/loads. And in the really old days of the first power panels from Trace, they did wire them the way maybe you are taking about Dan. With the main breaker as a main, and the PV/inverter connected on the switched side. But then PV is connected directly to the inverter and those old CC didn’t clamp that fast, and poof dead inverter. Amazingly I just “updated” a trace PP from way back a few months ago. I am of the opinion ( in the minority here) that fuses are not a good addition for protection of the conductors. They add complexity and more failure modes. ( I’ve seen class T fuse holders almost catch on fire). And now you are going to have to leave extra fuses $$$ and then insulated tools as well? And as others have pointed out, where do you mount them etc. And in my defense, mostly my conductors are pretty short so I don’t worry about that. If they were going a long ways, then I might reconsider, but I’d probably use a breaker instead. The only time I will use them is for larger parallel battery banks, but this is for the protection of the battery side, not the main conductors really. my 2c. jay peltz power > On Oct 23, 2015, at 7:30 AM, Dan Fink <danbo...@gmail.com> wrote: > > Esteemed Wrenches; > This creeps me out too and sometimes causes lack of sleep. > The Midnite Solar power panel install manual shows no OCPD on in DC + main > from battery bank to power panel. Easy to wire the main DC breaker to control > those conductors, but then you have a "self destruct" switch if system > shutdown and restart is not done in the proper order, IE PV and wind turbine > shut down first before battery bank. > For a class T fuse on the battery bank, it's a big $ ordeal because it has to > be outside the battery box in an enclosure per NEC. > So, recently I've just been making sure the conduit from DC battery mains is > sound up to the power panel. The only issue I can see is mice chewing 2/0 > cable inside the battery box -- which means the box wasn't designed right to > exclude rodents, or the owner has a lazy cat. > I'd feel much better if there was an OCPD NEC legal to attach right to the > main battery DC + and wire from there to power panel, but I don't think that > exists. > > > > > Dan Fink > Adjunct Professor, Ecotech Institute > IREC Certified Instructor™ for: > ~ PV Installation Professional > ~ Small Wind Installer > Executive Director, Buckville Energy > NABCEP / IREC / ISPQ Accredited Continuing Education Providers™ > 970.672.4342 <tel:970.672.4342> > > > On Thu, Oct 22, 2015 at 11:26 PM, Mbalchowsky <m...@seesolar.com > <mailto:m...@seesolar.com>> wrote: > It's ALWAYS good practice to install a current limiting fuse at the battery > bank, if fact it's very poor practice not to. We're working with a lot of > larger lithium ion phosphate manganese systems and I would not install them > without it. As far as working on someone else's install, make your contract > very clear as to what the customer can expect as far as your liability when > working on an existing system. The more detail, the better..... > > Sent from my iPhone > > On Oct 22, 2015, at 7:25 PM, Jerry Shafer <jerrysgarag...@gmail.com > <mailto:jerrysgarag...@gmail.com>> wrote: > >> I agree, fuse it >> >> Jerry >> >> On Oct 22, 2015 3:26 PM, "Tom Ruscitti" <trusci...@taitem.com >> <mailto:trusci...@taitem.com>> wrote: >> On battery based systems I always install a Class T fuse as close to the >> battery bank as possible. 690.71(C) is a little vague in requiring a current >> limiting fuse only where the available short-circuit current from the >> battery bank exceeds the interrupting ratings of the inverter breaker. >> Inverter breakers vary in their interrupting ratings and battery banks are >> big current sources when things go wrong, so it's just a sensible best >> practice. My question is about service work on systems we didn't install. >> We're quoting the second job this year for battery replacement where there >> is no current limiting fuse installed. It's always a tough question to judge >> what extra work might be required when you touch another contractor's >> system, but does anyone have an opinion about recommending or requiring the >> installation of a fuse at the battery box as part of the battery replacement? >> >> Thanks, >> >> - Tom >> >> -- >> Tom Ruscitti >> Senior Engineer >> >> Taitem Engineering, PC >> 110 S. 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