Kelly,

If I understand your situation, the AHJ is allowing you to use 
the existing grounding electrode/s as the (new for 2008) required 
array electrode, rather than adding an additional electrode closer to the array. 

He does want an additional GROUNDING ELECTRODE CONDUCTOR, sized appropriately, 
and, of course, run separately from the array circuit conductors, 
directly from the array to the existing electrode.

If this is the case, it makes sense. You dont want to depend on your 
EQUIPMENT GROUNDING CONDUCTOR, run with your circuit conductors, 
to carry energy from a lightning strike, for instance. Take that energy 
(renewable but undesired) to EARTH / GROUND as directly as possible.
Hope this helps.

Dick
Solarwind Electric
Bradford, VT



--- You wrote:
All,
This issue was discussed here about a year ago, before most jurisdictions
had adopted the 2008 Code and AHJ's started interpreting it.

Our current situation is a residential, roof-mounted PV array, with not an
extraordinary distance to the existing AC GEC. The AHJ has NOT required the
"additional PV" GE, but IS requiring the extra GEC from the array to the
AC/DC GE, on the grounds of (690.47D) "The dc grounding electrode conductor
shall be sized according to 250.166" (i.e. #8 min). We have the standard EGC
inside the conduit, running with the PV DC circuit conductors.

Is there any "grounds" for this requirement? What are your AHJ's requiring?

Thanks,

Kelly Keilwitz, P.E.
Whidbey Sun & Wind, LLC
Renewable Energy Systems
NABCEP Certified PV Installer
WA Electrical Administrator #KEILWKM923RB
987 Wanamaker Rd.
Coupeville, WA, 98239
360.678.7131
sunwind@whidbeysunwind.com
WA Electrical Contractor #WHIDBSW920MS
WA General Contractor #WHIDBSW946M1
--- end of quote ---

