Maximum current is defined in 690.8(A) as Isc x 1.25. Minimum OCPD size is defined in 690.8(B) as maximum current x 1.25 (Isc x 1.56). The maximum size, for PV source circuits, is the module maximum series fuse size.
Required conductor ampacity is the greater of Isc x 1.56 or Isc x 1.25 with all conditions of use factors (and the conductor must be protected by the OCPD under conditions of use). Brian On Fri, Feb 11, 2011 at 11:03 AM, <wire...@gmail.com> wrote: > In studying for NABCEP certification I am a little confused about whether > you multiply the short circuit current by 1.25 once or twice (1.56) in order > to calculate maximum circuit current in determining wire size. Same for > overcurrent protection. > > I have always done it twice (1.56) for both PV source circuit and PV output > circuit. Once for over irradiance and once for continuous use. > > But a handout at a recent seminar that I went to totally confused me. > > Can anyone spell it out very clearly? > > Thank you. > > Larry Liesner > Wirewiz > Westport, CT > Phone: 203-644-2404 > Fax: 203-557-0556 > wire...@gmail.com > www.wire-wiz.com > > > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Options & 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 > > -- ======================== Brian Mehalic NABCEP Certified Solar PV Installer™ PV Online Coordinator Solar Energy International Carbondale, CO 81623 http://www.solarenergy.org
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