Of course the objective in locating fuses is almost a catch-22. On the one hand they should be as close as possible to the batteries, on the other hand you can't locate the fuses in the same enclosure as the batteries as there is a chance that if they were to open, the arcing may ignite any hydrogen that is present.
We usually locate them immediately on the side of the box that the batteries are in, inside a jbox. -Glenn From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of frenergy Sent: Saturday, February 08, 2014 4:53 PM To: RE-wrenches Subject: Re: [RE-wrenches] DC Fusing/Breakers for Battery Circuits So help me out with a little more detail please. Example (Dan's configuration and my current in-progress install): 2 Strings of 8, L-16s for 48V. nom. Destination: the common pos bus at the bottom of a pair of 125 amp CBs as OCP for 2, VFX3648s. Positive battery current path: from each end of both battery string pos terminals, the next stop would be a (110 amp?) Class T fuse, one for each cable/string. Then cables from each of these fuses would land on one Bus (hefty chunk of copper bar stock) mounted on inside of battery box (backed up with Dan's cement board), combining the outputs of both batt strings. From this one bus, run 2 cables to the pos bus at the bottom of the 2, 125 Amp CB's (in this case provided in the OB-DC Flex enclosure, protecting the 3648s. A little simpler (better?) would be to just bolt the Class T fuses right to the bus in the battery box, eliminating some cable. Feedback?...and thanks, Bill Feather River Solar Electric 4291 Nelson St. Taylorsville, CA 95983 530.284.7849 / 6544 fax ----- Original Message ----- From: Dan Fink <mailto:danbo...@gmail.com> To: Allan Sindelar <mailto:al...@positiveenergysolar.com> ; RE-wrenches <mailto:re-wrenches@lists.re-wrenches.org> Sent: Saturday, February 08, 2014 12:05 PM Subject: Re: [RE-wrenches] DC Fusing/Breakers for Battery Circuits Allan; It's a topic much on my mind recently and i will provide a writeup soon. It's all very well documented. I do have photos, but they don't show the fire damage to the wooden battery box unfortunately, the client was a bit flustered getting all the batteries out of there after the incident and when I showed up he had already demo-ed the box. But the photos of the batteries themselves do tell the story rather well. There was another issue also.....his Xantrex power panel was wired with a 'self destruct switch' main battery cutoff. I did not design or install the panel. But his logical reaction in seeing smoke coming out of his battery box was to open the main battery disconnect breaker on the panel, which then put solar 140vdc onto the inverters inputs. Both were zorched by high voltage. He should have opened the solar breaker first, then the main DC. His homeowner's unsurance did cover most of it all. The batteries were 8 years old....end of lifespan situation. Lessons learned......OCP on parallel battery strings, and cement board liner in all battery boxes, if they are field built wooden. Dan Fink, Executive Director; Otherpower Buckville Energy Consulting Buckville Publications LLC NABCEP / IREC accredited Continuing Education Providers 970.672.4342 On Fri, Feb 7, 2014 at 10:36 AM, Allan Sindelar <al...@positiveenergysolar.com> wrote: Dan, Do you have a writeup on that event? Any photos? I have many plywood battery enclosures in the field. Thanks, Allan Allan Sindelar <mailto:al...@positiveenergysolar.com> al...@positiveenergysolar.com NABCEP Certified PV Installation Professional NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder, Positive Energy, Inc. A Certified B CorporationTM 3209 Richards Lane Santa Fe, New Mexico 87507 505 424-1112 <tel:505%20424-1112> office 780-2738 cell www.positiveenergysolar.com <http://www.positiveenergysolar.com/> On 2/7/2014 10:26 AM, Dan Fink wrote: Does anyone have any elegant solutions to this? It's really time consuming and ugly to run big parallel battery string wires *out* of the battery enclosure to class T fuses, then back into the battery box. It looks very ugly and DIY, and in conduit adds a few hundred to the install cost just for labor. The Class T fuses and blocks themselves are not particularly expensive. I have been recommending parallel fusing on battery banks of 2x8 L16s and over now, after a nearly tragic incident with a bad cell that shorted. The (perfectly legal) wooden battery box made the fire much worse. A pet peeve of mine. Dan Fink, Executive Director; Otherpower Buckville Energy Consulting Buckville Publications LLC NABCEP / IREC accredited Continuing Education Providers 970.672.4342 _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org _____ _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
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