The 120% rule applies to both commercial and residential from the 2008 code on.
Kirk Herander VSE On Jun 17, 2013, at 2:58 PM, Allan Sindelar <al...@positiveenergysolar.com> wrote: > Pekka, > I believe that the 120% rule is only for residential application. Unless it's > changed (and I don't do commercial any more, so I may be all wet here) you're > limited to 100% on commercial applications. The assumption is that a > commercial service may already be running at or close to full ampacity, while > residential is unlikely ever to do so. > Allan > > Allan Sindelar > al...@positiveenergysolar.com > NABCEP Certified PV Installation Professional > NABCEP Certified Technical Sales Professional > New Mexico EE98J Journeyman Electrician > Founder and Chief Technology Officer > Positive Energy, Inc., a Certified B CorporationTM > 3209 Richards Lane > Santa Fe, New Mexico 87507 > 505 424-1112 office 780-2738 cell > www.positiveenergysolar.com > > On 6/17/2013 11:33 AM, Pekka Laine wrote: >> Dear Fellow Wrenches, >> >> We have a small 50kW 120/208V commercial job with five 9kW 3PH inverters, >> each outputting max. 25A. We are landing those into a dedicated load center >> with five 40A breakers. Doing the math, 5 x 25A x 1.25 = 156.25A, we would >> need a 160A breaker. This also equals to the maximum we can backfeed into a >> 800A/800A Main Service on the load side according to the "120%" rule. >> >> The problem now is that we cannot locate any kind of 160A breaker or even a >> 160A fuse for a AC disconnect. >> >> Has anybody ever done this without doing a "line-side tap?" It is hard to >> believe that there wouldn't be an existing solution to landing maximum PV >> into a 800A service. Are we missing something? >> >> Any good ideas or comments would be appreciated. >> >> Sincerely, >> >> Pekka Laine >> >> President >> Photon Solar Power Inc. >> www.PhotonSolarPower.com >> Cell. 760-556-8170 >> Toll Free 888-SUN-ACDC >> CA Lic. #933648 >> NABCEP Certified PV Installer # 032611-174 >> _______________________________________________ >> 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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