Ray,
Thanks for the note and I see your point about "operating at greater than 50 v". Does anyone else have an opinion on the operating voltage for batteries? I know that NEC 480.2 defines the nominal battery voltage as 2 volts per cell for lead-acid and I believe I have a code interpretation book lying around that states that this is what you apply to 250.162 but I don't have much info other than that. Best, August *From:* re-wrenches-boun...@lists.re-wrenches.org [mailto: re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Ray Walters *Sent:* Monday, April 15, 2013 1:48 PM *To:* RE-wrenches *Subject:* Re: [RE-wrenches] Fuse sizing in battery circuits Hi August; 250.162(A) says "operating at greater than 50 v", which a 48 v nominal system operates most of the time at over 50 v, at least when solar charging and/or selling back. We used to get dinged many years ago for using breakers rated at 50v dc on 48 v systems. John Wiles used to insist we use the highest possible voltage (Voc of modules on coldest day) Personally I prefer ungrounded systems, so I'm not saying there's anything wrong from a safety stand point, just that inspectors here don't see it the same way. R.Ray Walters CTO, Solarray, Inc Nabcep Certified PV Installer, Licensed Master Electrician Solar Design Engineer 303 505-8760 On 4/15/2013 2:20 PM, August Goers wrote: Hi Drake, The Sunny Island System runs at 48 V nominal so I don't believe 250.162(A) applies. We have some really savvy inspectors in the Bay Area and they were happy for us to be ungrounded since we're operating at 48 V. Yes, the actual voltage might go above 50 V when charging but I believe it is the nominal voltage that the code cares about. Best,
_______________________________________________ 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
