PV Grounding [RE-wrenches]

[Ray Walters]

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WE use a braided, plated copper ground strap (Anixter) that is about  
8 ga equivalent. It is what I saw being used on a commercial tracking  
system over 20 years ago, and its all we use for exposed module  
grounding.
IMHO, using THHN outside is not only not NEC, but is just bad  
practice. I know its not a current carrying conductor, and doesn't  
need the insulation, but I've seen plenty of it cracking and peeling.  
Looks like crap.
There's that little thing in the code (110.12) "Electrical equipment  
shall be installed in a neat and workmanlike manner"
Without the insulation, stranded 10 ga isn't allowed for exposed  
locations. see 250.64 B
THe real solution is allowing products like the WEEB grounding system  
and use the mounting frame itself as the grounding conductor.  
Commercial buildings allow the steel structure to be the grounding  
conductor, on arrays its just a matter of dealing with the aluminum  
to steel galvanic reaction issues, and then getting the inspector  to  
sign off on it.

Ray Walters

On Apr 15, 2008, at 6:42 PM, Mark Frye wrote:

>
> I have taken to using 8# bare stranded from module all the way  
> through to
> the point of connection at the ac system GEC.
>
> i too have heard of folks disallowing the #10 GRN STD as a PV  
> equipment
> ground, something about the insulation is not rated for UV exposure or
> extreme current during lighting strike, but.....who needs  
> insulation on an
> equipment ground? (isolated ground systems being a separate issue)
>
> Would definently be interest in a good explanation why this should be
> disallowed.
>
> Mark Frye
> Berkeley Solar Electric Systems
> 271 Vistamont Dr
> Grass Valley CA 95945
> (530) 401-8024
> www.berkeleysolar.com
>
> -----Original Message-----
> From: Peter Parrish [mailto:peter.parrish at calsolareng.com]
> Sent: Tuesday, April 15, 2008 5:31 PM
> To: RE-wrenches at topica.com
> Subject: PV Grounding [RE-wrenches]
>
>
> After all these years I must confess I was stymied by the comment of a
> self-styled expert on grounding. He said that grounding of roof  
> mounted PV
> modules cannot be accomplished with stranded wire -- period. We were
> discussing 10 AWG, 19 strands vs 10 AWG solid, so I didn't venture  
> beyond
> the case at hand.
>
> We normally use 10 AWG solid but occasionally we run out and use 10  
> AWG THHN
> Green 19 strand in a pinch (module to module, rail to rail or sub- 
> array to
> sub-array)
>
> For the record, the PV modules had a series fuse rating of 15A and  
> we were
> paralleling two strings at the inverter, which was a Xantrex GT4.0  
> with a
> 600 volt 1-Amp ground fault protection fuse.
>
> Is he right?
>
> - Peter
>
> California Solar Engineering, Inc.
> CA Lic. 854779, NABCEP Cert. 031806-26
> peter.parrish at calsolareng.com
>
>
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>

R. Walters
Solarray.com
NABCEP # 04170442	




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