[RE-wrenches] ground

[Kent Osterberg]

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
>