PV Ground Rods

[jcrawford]

I know these grounding issues are a hot topic over here at the Mike Holt forums. I'm listening to a PV training put on by IREC (http://www.pvonlinetraining.org/) which is stating that if no grounding electrode (building steel, other ground rod, etc) is withing 6ft of some part of a solar array, you have to drive a second rod. They're basically saying that all pole mounted arrays must have auxiliary ground rods because they are inevitably over 6ft from the building's grounding electrode. My understanding was that you COULD drive an auxiliary electrode per 690.47(3)(D), but that its generally not recommended for safety reasons.

Does anyone know where this 6ft rule is found in the NEC, and why wouldn't you be able to just create a path from the array to an existing EGC which leads back to the home's existing AC ground rod?

 

[jcrawford]

I guess I'm just confused with the 2014 edition of the NEC. It certainly appears as though 690.47(D) is REQUIRED for say, ballasted ground mount PV, though my Mike Holt 2014 Solar book suggests that it is merely ALLOWED (and unrecommended). In fact, Mike says in his video that the name "auxiliary" means it is not required. "Auxiliary" is not defined in the definitions section as such... Anyone have clarification?

https://www.youtube.com/watch?v=YuDqXFvRv94

 

[jaggedben]

This is the hot new forum topic for people getting onto the 2014 NEC. And understandably so, since 690.47(D) was removed in the 2011 cycle, put back in the 2014 cycle in a modified version, and changed to no longer be a requirement in the 2017 NEC.

Congrats on finding the video.
See also recent threads:
http://forums.mikeholt.com/showthread.php?t=181119
http://forums.mikeholt.com/showthread.php?t=181213

I would agree that pole mounted arrays now require an electrode because it's a new structure and the NEC requires a grounding electrode at a structure with a solar array. That continues to be required in the 2017 NEC, while the rest of 690.47(D) will no longer be required.

The 6ft distance is in an exception to 690.47(D) in the 2014 code. Some people, including people very close to the code making process (e.g. Bill Brooks) believe that the 6ft exception can be applied to any structure that already has an electrode. But your mileage with your AHJ may vary.