Grounding from roof array, EGC or GEC?

[tilden]

I'm currently talking with an inspector about what grounding requirements there are for a roof mounted array. My interpretation is I believe similar to this previous post
http://forums.mikeholt.com/showthread.php?t=156677&highlight=array+grounding
where in #8 at the end they say

Under 2011 it definitely just needs to go from inverter to main.

It is my understanding that the ground from the inverter to array only needs to be an EGC, so it's sized via 690.45(A) which points to 250.122. The inspector is saying that we need a GEC all the way to the array, and that it would need to be sized per 250.166 with #8 minimum.

We did the install in a new house and they've already spray foamed and drywalled so it's not very easy for us at this point to just go put up an extra #8 ground and not worry about it anymore. If of course we do need to have a GEC running to the roof then so be it - but I'm just not seeing that as a requirement in the code. 690.47.(C).(3) is how we have the combined DC GEC and AC EGC between the AC panel and inverter.

I do realize that 690.43(C) says the array has to be bonded to the grounding system, and read on this page (Equipment Bonding Section, end of first FPN) from Mike that

this can be done via an equipment grounding conductor.

but wasn't sure what justification I could tell my inspector that this doesn't need to be a GEC going back to the grounding system.
http://ecmweb.com/code-basics/nec-rules-alternative-energy-systems-part-1

Finally - In this thread Sunking addresses this in post #33, saying

However it is still required to bond the PV frames and racking directly to a GES with a dedicated GEC.

which I can't figure out where this requirement comes from.
http://www.solarpaneltalk.com/showthread.php?10216-grounding-question-and-confusion/page4

The inspector is also saying it needs to be a GEC because the DC conductors are a DC system which requires a GEC all the way to the panels. I believe this would be for system grounding, but from what I read the system grounding can take place at essentially any point on the DC conductors per 690.42, including at the inverter, which is the case anyway with a ground fault protection system per the exception.

If I'm missing something I want to be sure I get it right so we can do future jobs correctly, but if the way I've ready everything is correct I want to be sure I provide ample support to this inspector as I want to be sure we get the right precedent set for others too.

 

[Smart $]

... 690.47.(C).(3) is how we have the combined DC GEC and AC EGC between the AC panel and inverter.

....

690.47(C)(3), aside from the other requirements, says the combined EGC/GEC must be the larger size of 250.122 or 250.166. You didn't say what size you ran or location of inverter(s) with respect to array. The way I see it, there is no requirement for the GEC-sized grounding conductor be continued beyond the inverter(s) if the array is remote to the inverter(s).

 

[AdamS]

The inspector is full of it. Inverter to array/module framing = EGC

Inverter to main panel= GEC.

Tell him to buy this book so he can do his job properly.http://www.mikeholt.com/bookitem.ph...rchtext=&product_type=Book&category_from=Book

I'm an installer myself and have dealt with inspectors like this and have had to whip out that book to silence them.

 

[Zee]

Inverter to main panel= GEC.

yup.
Your logic is good.
Only EGC in rack on dc systems.

However, If it is a MICRO inverter system with the older micro-inverters.... then a GEC is needed on roof!
"Maybe that is what you remember", you can kindly suggest to the inspector.....

You can even argue it to the other extreme: you may even demonstarte the lack of need for a GEC from inv. - main panel if it is a TL inverter.....