350 feet to barn- grounding [RE-wrenches]

[daryl_solar at yahoo.com]

Hi Steve
The code calls for two types of ground.  and equipment ground, which had some changes in 2005 requireing an equipment ground for any electrical equipment, equipment grounding conductor)  such as even remote buildings, and of course solar.  Sized by 250 and 690.45 (I think)  The 2008 code clairifies the need for a ground near the array, (grounding electrode system) The purpose is to reduce the electrical damage from induced sky voltage changes.  I have had success where I have added a good grounding electrode system to an array having repeted electrical damage. 

The surge arrestor hopefully trims the module line to line, and line to ground voltage surges.  These surges are reduced by having a well grounded array (earth grounded).  The code allows this egc and ges to be one conductor, sized at the largest required size. 

The running of the ground conductor in bare copper outside the conduit, is to help acheve a ground, but caution many soils have poor conductivity near the surface, and I recomend two ground elements and use a ground tester to determine the ground resistance.   

Hope this is helpful.  
Darryl
--- On Sun, 6/29/08, Dick Ratico <Richard.L.Ratico at VALLEY.NET> wrote:

> From: Dick Ratico <Richard.L.Ratico at VALLEY.NET>
> Subject: Re: 350 feet to barn- grounding [RE-wrenches]
> To: RE-wrenches at topica.com
> Date: Sunday, June 29, 2008, 6:20 PM
> Hi Steve,
> 
> The first paragraph of NEC 690.43 is unequivocal in
> requiring an equipment
> grounding conductor between the array and other equipment.
> In my opinion, any
> inspector, grumpy, euphoric, or anything in between, cannot
> interpret it
> otherwise.
> 
> As Ray points out, he may permit it to be direct buried in
> the trench outside
> the conduit, rather than inside. He may even permit it to
> be direct buried on
> the opposite side of the trench from the conduit. There was
> a thread here, in
> the middle of this month, which discussed this.
> 
> Dick Ratico
> Solarwind Electric
> Bradford, VT 
> 
> You wrote:
> I have a grid tied installation where the panels are 350
> ft. from the 
> inverter. This is not a voltage drop problem because I have
> 370 Vmp DC 
> to work with so wire is sized < 1% Vd.
> 
> Is there any reason to run a ground wire from the barn to
> the house in 
> the underground conduit? I can't think of one. The 4
> strings on the 
> barn will be combined at the barn, with a lightning
> arrestor and ground 
> rod installed.
> 
> At the house the DC disconnect will be grounded on the AC
> and DC side.
> This seems fine to me but there is a gnawing subconcious
> feeling that 
> makes me ask this question. Or maybe its the grouchy
> inspector.
> 
> 
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