From: Kirk Herander, VSE [mailto:k...@vtsolar.com] Sent: Sunday, April 10, 2011 10:02 PM To: 'William Miller' Subject: RE: [RE-wrenches] 690.4 (B) ???
Thanks William, IMO you are right on in your interpretation. I can see no wiggle room for the inspector because of the definitions in 690.2. So we will see what happens. BTW, I hope your local inspector reversed themselves when presented the same "evidence". That said, 690.4(B) tin the 2008 NEC is ridiculously vague. PV inputs/outputs are not spelled out as DC (which by definition they are). Does "unless connected" mean unless the pv inputs and outputs are tied together (and why woudn't they be in a jbox or fused array combiner), or that the pv inputs and outputs are tied to the "separate" system conductors in the same raceway? Is this the most poorly worded paragraph in 690? It seems so right now. Just got my new 2011 NEC (comments version) but I am without it traveling and can only hope it's been clarified. Kirk Herander Vermont Solar Engineering 802.863.1202 NABCEP(tm) Certified Solar Installer NYSERDA-eligible Installer VT Solar Incentive Program Partner _____ From: William Miller [mailto:will...@millersolar.com] Sent: Sunday, April 10, 2011 2:19 AM To: k...@vtsolar.com; RE-wrenches Subject: Re: [RE-wrenches] 690.4 (B) ??? Kirk: When you say inverter combiner, I am confident you mean the device combining the AC output conductors of multiple inverters. I got the same jive from an over zealous inspector once, but he and your inspector are just plain wrong. Examine and show them the diagram in the code book of PV source and output conductors (690.2). These are all DC PV conductors, not AC conductors, and, assuming the statement in the paragraph above is correct, the passage has no application here. This is a rookie inspector mistake. Good luck, William PS: By saying the source and output connectors are connected together, this is an oblique way of describing the PV combiner, the one point where PV source and output circuits are connected together. WM At 06:10 PM 4/9/2011, Kirk Herander, VSE wrote: 2008 NEC states that: (B) Conductors of Different Systems. Photovoltaic source circuits and photovoltaic output circuits shall not be contained in the same raceway, cable tray, cable, outlet box, junction box, or similar fitting as feeders or branch circuits of other systems, unless the conductors of the different systems are separated by a partition or are connected together. Can anyone describe and give an example of what "connected together" means to inverter PV circuits in the same conduit as a branch (load) circuit? I have a single existing PVC conduit to a barn with an AC load subpanel. I want to run the output conductors of an inverter combiner panel in the barn through the same conduit to get to be main building. The fill / derating calcs work to do this. The inspector says I have to run a new conduit for the AC inverter combiner because the subpanel feeder and the combiner output conductors are "not connected". But they are both connected to the main building panel. Any insight will be appreciated. Thanks. I've also been told that the NEC 2011 comments on 690.4 (B) clarify this. Can anyone comment? Obviously I am not mixing DC and AC conductors. Kirk Herander William Miller Miller Solar Voice :805-438-5600 email: will...@millersolar.com http://millersolar.com <http://millersolar.com/> License No. C-10-773985
_______________________________________________ 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
