I agree with Ray. The best ground clamp I have found for the money ($1600) is the Fluke 1630 ,its real easy to use and work well.
On Sat, Oct 1, 2011 at 1:41 AM, Ray Walters <r...@solarray.com> wrote: > I'm a big fan of grounding at the array, and was sorry to lose 690.47D > (which also clearly allowed the structure to be considered an electrode) . > I think if you look at the sq ft. of metal in contact with the concrete, > you can make a credible case for the frame fitting the definition of an > electrode. IMHO, it's all about a low impedance path to ground. Whether > it's 20 ft of 1/2" rebar, or 4 ft of 6" diam pipe, or 4 ft of 2" x 2" angle > iron, its all roughly the same required 2 sq ft of surface area in contact > with the concrete. > > Actually if you want to be a real stickler and also enforce 250.53A2, a > tough AHJ might demand 2 electrodes at the array in addition to the > structural grounding all ready present. > Me? I like the exception if the measured ground impedance is less than 25 > ohm. Most inspectors will be more than satisfied, if you just show them a > quick reading with a clamp-on ground impedance tester. > What If you're still over 25 ohms? If you're in lightning country, you > really should sink another electrode anyway. > > Ray > > > On 9/30/2011 7:04 PM, Kent Osterberg wrote: > >> Ray, >> >> I believe that a pole-mounted or grounded-mounted PV array is considered a >> structure and requires a ground electrode per 250.32. Perhaps the exception >> would cover the possibility a installing very small system without a ground >> electrode. >> >> Kent Osterberg >> Blue Mountain Solar, Inc. >> >> >> >> Ray Walters wrote: >> >>> I've also used 250.52A(7) defining plate electrodes. A 6" Sch 40 pipe 4 >>> ft in the ground has more than the required 2 sq ft of surface metal, and is >>> at least the required 1/4" thickness. >>> Also, the 2011 NEC dropped 690.47 D which required a grounding electrode >>> at the array. Are you sure you still need this? I believe 2011 only requires >>> you bond all the metal to the EGC, as always. >>> >>> Ray Walters >>> >>> On 9/30/2011 8:24 AM, Kent Osterberg wrote: >>> >>>> The requirements listed in 250.52(3) were changed in 2011. The rebar >>>> used is allowed to be near the bottom of the footing or in vertical >>>> foundation walls that are in direct contact with earth. If there was in >>>> doubt in the past that the rebar in the concrete of a pole mount was a >>>> suitable grounding electrode, the changes in 2011 should remove it. >>>> >>>> Kent Osterberg >>>> Blue Mountain Solar, Inc. >>>> >>>> Richard L Ratico wrote: >>>> >>>>> As Dan points out, 250.52(A)(3) specifies several installation >>>>> requirements in >>>>> order for a concrete encased electode to qualify as a permitted >>>>> Grounding >>>>> Electrode. A pole mount foundation would certainly qualify if it met >>>>> those >>>>> requirements. >>>>> >>>>> Even if the requirements are not met, IMHO, any opportunity to >>>>> inexpensively >>>>> increase the grounding integrity of a system should not be overlooked, >>>>> particularly in lightning country. Of course, a code compliant >>>>> Grounding >>>>> Electrode System is still required. Bonding a non compliant, but never >>>>> the less, >>>>> very substantial additional "electrode" to that system would not hurt >>>>> anything >>>>> and quite possibly help considerably. >>>>> Dick Ratico >>>>> Solarwind Electric >>>>> >>>> >>> ______________________________**_________________ >> List sponsored by Home Power magazine >> >> List Address: >> re-wrenc...@lists.re-wrenches.**org<RE-wrenches@lists.re-wrenches.org> >> >> Options & settings: >> http://lists.re-wrenches.org/**options.cgi/re-wrenches-re-**wrenches.org<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<http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org> >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.**htm<http://www.re-wrenches.org/etiquette.htm> >> >> Check out participant bios: >> www.members.re-wrenches.org >> >> >> >> >> > ______________________________**_________________ > List sponsored by Home Power magazine > > List Address: > re-wrenc...@lists.re-wrenches.**org<RE-wrenches@lists.re-wrenches.org> > > Options & settings: > http://lists.re-wrenches.org/**options.cgi/re-wrenches-re-**wrenches.org<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<http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org> > > List rules & etiquette: > www.re-wrenches.org/etiquette.**htm<http://www.re-wrenches.org/etiquette.htm> > > Check out participant bios: > www.members.re-wrenches.org > > -- *James B Rudolph NABCEP Certified PV Installer *
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