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
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