I don't see it in your comments. At least that wasn't clear. Anyway, in that case there is absolutely no reason to use the inverter ground clip. The whole purpose of the inverter-> rail WEEB is to eliminate the ground wire.
Take a look at the Enphase App Note here: http://www.enphaseenergy.com/downloads/EnphaseAppNote_WEEB_Installation. pdf It starts out, "As an alternative to installing a continuous grounding electrode conductor connected to each microinverter chassis, a grounding washer may be used to ground the microinverter to grounded racking." It couldn't be more clear for an inspector, but I understand that sometimes it's hard to convince them. Hope this helps! Jason Szumlanski Fafco Solar -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Kirk Herander, VSE Sent: Thursday, March 03, 2011 8:46 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter "As an aside, why didn't you use approved WEEB's to bond the inverters to the rails? This eliminates the ground wire to each inverter. Simpler IMHO." I did. It is in my comments. Kirk Herander Vermont Solar Engineering 802.863.1202 NABCEP(tm) Certified Solar Installer NYSERDA-eligible Installer VT Solar Incentive Program Partner -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jason Szumlanski Sent: Wednesday, March 02, 2011 6:56 PM To: RE-wrenches Subject: Re: [RE-wrenches] grounding the Enphase inverter As an aside, why didn't you use approved WEEB's to bond the inverters to the rails? This eliminates the ground wire to each inverter. Simpler IMHO Anyway, what we are seeing in some jurisdictions is the requirement for the additional grounding electrode (690.47(D)) even when there is a good argument that the premises grounding electrode via the MDP is arguably "as close as practicable." I think we've used Exception No. 2 about once or twice. What it basically looks like, assuming you bond inverters and panels to rails using WEEBS, is [insert deep breath] a bare ground wire from the additional grounding electrode up to the roof, through lay-in lugs (WEEB-LUGS) on each rail, into a junction box, irreversibly crimped to a #6 THWN-2 green, down to the premises GEC via the MDP ground bus bar, hitting any metal enclosures and grounding bushings along the way. If you are using D380's with a green ground in the AC Interconnect cable, that get's irreversibly crimped in the J-box, too. The GEC can function as the EGC, fortunately. Some inspectors have wanted to see the ground rods tied together with another wire, even if it means trenching around the entire building, digging up driveways and sidewalks, and calling in 811. I've reached the boiling point more than a few times over this stuff. And you're right - none of it makes much sense... I recently asked Jacob Michaels at Enphase if he could come up with an application note that clarifies grounding requirements relative to NEC 2008 and 2011 once and for all. Circumstances will always dictate requirements, but AHJ's, at least around here, often put a good deal of weight on an App Note from a manufacturer. We'll see! Jason Szumlanski Fafco Solar -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Kirk Herander, VSE Sent: Wednesday, March 02, 2011 6:07 PM To: 'RE-wrenches' Subject: [RE-wrenches] grounding the Enphase inverter My AHJ is making me ground the Enphase inverters AND use a separate equipment ground for modules / mounting rails. The panel frames are grounded to mounting rails via WEEBS, rails are grounded together using WEEB lay-in lugs and copper wire, this ground wire makes its way to AC panel gnd bar, where it is connected to ground rod via grounding electrode conductor, as normal. AHJ insists I also install dedicated continuous ground wire from each Enphase inverter gnd clip directly to the building GEC or to the ground rod itself. Mind you, the inverter enclosure, to which the gnd clip is attached, is already grounded to the mounting rails via WEEBs. So what I have done is created a parallel ground between the mounting rails and the GEC, a.k.a a ground loop, a.k.a. a current divider. Short circuit current from the Enphase is going to be split between the two paths to ground. The only way this grounding scheme makes any sense to me is if the inverters were totally isolated from the rails using a non-conductive tape or washer between the rail and inverter at point of attachment. Just removing the WEEBS would not isolate the two. My AHJ is basically trying to apply the grounding rules of a string inverter (dedicated gnd directly from inverter to GEC) to a micro-inverter, but I feel this method, aside from redundancy and T $ M, is little short in the "best practice" or "safest" categories. I'd be interested in other takes on this. Thanks. Kirk Herander Vermont Solar Engineering 802.863.1202 NABCEP(tm) Certified Solar Installer NYSERDA-eligible Installer VT Solar Incentive Program Partner _______________________________________________ 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 _______________________________________________ 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 _______________________________________________ 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
