[RE-wrenches] 690.47

[R. Walters]

Much of the confusion seems to be from the older versions of the  
code. I actually find the 08 version to be less confusing overall (I  
do have my issues though). It allows the WEEB system for instance,  
which greatly speeds installations, and allows the array support  
structure to be used as the grounding electrode (in some cases). It  
seems to clarify some of the bonding issues as well. But with any  
attempt to clarify comes more confusion. I personally don't see any  
issue at all with the Enphase inverters. 690.47C (3) says "a single  
conductor shall be permitted to be used to perform the multiple  
functions of DC grounding, AC grounding, and bonding between AC & DC  
systems."
Module is bonded to the array frame, frame is bonded to ground.  
Enphase is bolted to the module frame (bonded) and bonded via its EGC  
back with the AC conductors to the main ground buss.
Everyone is always trying to over complicate grounding issues  
relative to PV systems. We just need to follow the same time tested  
methods used on other wiring systems: Exposed metal is bonded to  
ground in some reasonable manner, try to avoid ground loops, size the  
EGC to table 250.122.....Now just to decide where it becomes a GEC.....

Ray Walters
Solarray.com
NABCEP # 04170442	




On Jun 17, 2009, at 5:15 PM, Marv Dargatz wrote:

> Keith,
>
> The whole grounding issue has been very contentious, confounding,  
> and confusing.  The introduction of the changes with the 2008 NEC  
> seems to have complicated things further.
>
> Also, just a general comment; in general (there will be exceptions  
> for larger systems, depending on electrical configuration), this  
> code section applies equally to all PV inverters.  There should be  
> no difference with an Enphase installation and a traditional string  
> installation.
>
> What version of code are you referencing?  2005 and 2008 differ  
> slightly.  I'd like to get a consensus on all of these grounding  
> issues.  It's too late for the 2011 code, but maybe we can clear  
> this up with the 2014 code.
>
> BTW, the explanatory note after paragraph 690.47(C)(8) in the 2008  
> handbook offers some clarification.
>
> I'm anxious to get John W. and Bill B.'s opinion on this.
>  See Ya!
>
> Marv
> Enphase Energy
> 707 763-4784 x7016
>
>
> Keith Cronin wrote:
>>
>> Hello
>>
>> A discussion came up today about 690.47(C)(1)+(2) in regards to  
>> using the Enphase products and the applicability of needing a  
>> separate ground rod for the DC?
>>
>> Anyone get any feedback from their colleagues or inspectors  
>> regarding this and how they approached this?
>>
>> The discussion also swirled around them both being bonded  
>> regardless, so the question of necessity was in question.
>>
>> Thanks
>>
>> Keith
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