Folks, In looking at a circuit breaker based re-combiner for the first time, I am now pondering the meaning of the Exception below:
NEC 2014 690.8 (B) Conductor Ampacity. PV system currents shall be considered to be continuous. Circuit conductors shall be sized to carry not less than the larger of 690.8(B)(1) or (2). (1) One hundred and twenty-five percent of the maximum currents calculated in 690.8(A) before the application of adjustment and correction factors. Exception: Circuits containing an assembly, together with its overcurrent device(s), that is listed for continuous operation at 100 percent of its rating shall be permitted to be used at 100 percent of its rating. Just to be clear, it is only the assembly that can be used at 100 percent of its rating. (Isc*number of strings*1.25) The conductors in the circuit still have to be sized for continuous operation (Isc*number of strings*1.25*1.25). I ask because a vendor with a 100% circuit breaker re-combiner states in their cut sheet that use of the device "allow smaller home run cable sizes from the string combiner to the inverter". Is anyone aware of a means by which this claim can be substantiated? Thanks, Mark Frye Berkeley Solar Electric Systems _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
