[RE-wrenches] Grounding Requirement Question

[Ray Walters]

I think 690.47 C 3 covers this in the new 2011 code. The info notes 1 & 
2 also yield more clarification. As always confusion reins until we get 
some actual interpretation from Bill Brooks or John Wiles, as all of 
this was completely rewritten. Feel free to correct me, any and 
everyone, but this is my humble interpretation:
The E-panel provides the required combined AC & DC grounding busbar (in 
note 1) Note 2 says you can use the existing premises grounding system, 
and C(3) says the AC EGC can be combined with the DC GEC and run back to 
the premises AC grounding busbar in the same conduit as your AC conductors.
I think the main thing to check here is that you have properly sized the 
single combined conductor (AC EGC/  DC GEC) and that it is unspliced 
from the E panel to the main AC grounding busbar, and finally, that the 
existing AC GEC runs directly from that busbar to the grounding electrode.
Its pretty clear IMHO that you don't need to run a separate GEC all the 
way back to the grounding electrode (unless you're not on 2011 code?)

BTW, I usually sink a supplemental ground rod direct from the E-panel 
for lightning protection ( and to satisfy 2008 code) but my read is that 
is no longer required by 2011 code as 690.47 D was deleted.
I love how some folks act like you're going to burn the place down if 
you don't absolutely follow current code, and a couple of years later 
the code completely changes its mind, again, and again.....:)

Ray Walters


On 9/6/2011 1:59 PM, Aaron Mandelkorn wrote:
> Wrenches,
>
> Just installed a Magnum MS-PAE battery based system on an E-Panel 
> distribution box and my inspector seems to have an issue with the 
> grounding.  He is saying that I must run an additional GEC down to the 
> ground rod because I am dealing with two separate grounding systems. 
>  The DC and AC side of the grounding system shares the same ground 
> buss bar in the E-Panel so why wouldn't a single GEC down to the 
> ground rod suffice?  The buss bar is where the two systems get 
> grounded together rather than at the rod.  The inspector is telling me 
> to either dig up the rod and run an additional GEC down to it or 
> connect the additional GEC to the existing with an irreversible 
> splice.  Am I missing something here?  This requirement just seem 
> redundant and wasteful.  If I do have to make the correction I will be 
> going with the splicing option.   Some advise on irreversible splices 
> would also be greatly appreciated.  I can't seem to source them 
> locally and have never used them before.  Thanks for any help.
>
>
> Aaron Mandelkorn
> NABCEP Certified PV Installer
>
> Renewable Energy Outfitters
> (970)596-3744
> reosolar at gmail.com <mailto:reosolar at gmail.com>
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>
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