I am not aware of any type of installation where the NEC would require bundling in a gutter. I have seen some non-metallic raceways with built-in partitions for low-voltage and line-voltage wiring, but of course this type of product wouldn't be applicable for the AC/DC separation you're looking for. Anyway, you should be careful with bundling, because although it makes for a neat installation, your AHJ might consider tightly grouped conductors in a gutter as requiring derating, as if they were sharing a raceway. Typically this would not be an issue for solar installations, since we're increasing wire sizes over minimum requirements in order to minimize voltage drop / wire resistance losses, but if you had say, five strings, and you bundled the 10 DC wires together for a distance of 24" or more, your derating factor may have just hit 50%, and that's in addition to any derating that might be required by ambient temperature. Just keep in mind that any current carrying conductors that are bunched together with zip ties just might run a bit warmer and thereby have increased resistance. I heard a story somewhere once about a homeowner who thought it would be very workmanlike to _braid_ all the home runs together as they left the service panel. According to the story, the AHJ took a dim view of this and wrote an ampacity correction based on NEC 310.15(B)(2) "Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway of Cable". This makes sense when you consider that the braided romex was essentially one big cable.
-Hans Hans Frederickson Project Manager Frederickson Electric, Inc. www.fredelectric.com ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Drake Chamberlin Sent: Thursday, September 24, 2009 2:19 PM To: RE-wrenches Subject: Re: [RE-wrenches] AC & DC in Raceway Bundling is a good idea, I to that too. But where does it say we have to do it? At 09:43 AM 9/24/2009, you wrote: Nik, we always use 4x4 gutters when ever possible - keeps things clean and neat - as long as insulation voltage rating is same on all wires and wires are bundled (AC and DC - tie wraps or tape) and it's all from the same system (house wiring is another system) then it's OK....... Max Balchowsky SEE Systems From: "Nicholas Ponzio, Building Energy" <[email protected]> To: RE-wrenches <[email protected]> Sent: Thursday, September 24, 2009 4:02:21 AM Subject: [RE-wrenches] AC & DC in Raceway Wrenchers, What's the deal with mixing AC and DC conductors in a raceway? The job in question has a 6x6 wireway under the inverters. Conductors will have their own conduits but is it ok for them to share the wireway? Thanks in advance for clarification on this, Nik -- Nicholas Ponzio Building Energy 1570 South Brownell Road Williston, VT 05495 t: 802-859-3384 x15 f: 802-658-3982 www.BuildingEnergyVT.com "Building Solutions for a Sustainable Future" _______________________________________________ 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 <http://www.members.re-wrenches.org/> Drake Chamberlin Athens Electric OH License 44810 CO License 3773 NABCEP TM Certified PV Installer Office - 740-448-7328 Mobile - 740-856-9648 _______________________________________________ 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
