So you pick a conductor size from 310.16 (90 deg column) and then adjust for conditions of use. That number has to be greater than Isc x 1.25.
OCPD has to protect Isc x 1.56. On Fri, Feb 11, 2011 at 2:18 PM, Brian Mehalic <[email protected]>wrote: > 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, <[email protected]> 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 >> [email protected] >> www.wire-wiz.com >> >> >> >> _______________________________________________ >> List sponsored by Home Power magazine >> >> List Address: [email protected] >> >> 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 > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > 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 > > > -- Larry Liesner System Design Elektron Solar, LLC 16 Ketchum St. Westport, CT 06880 203-557-3127 (office) 203-644-2404 (cell) 203-549-0977 (fax) [email protected]
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