[RE-wrenches] GEC for Enphase inverters

[R Ray Walters]

HI BIll;

I'm still slightly confused: 
I think you are saying that the #8 can go straight to the service panel grounding buss? (as per 690.47(C)6&8) 

What about 690.47 (D) that requires an array ground to go to a supplemental electrode installed "as close  as practicable to the array....."
For Enphase, can we apply Exception 1 "....electrode not required, where the load served by the array is integral with the array" ?

R. Walters
ray at solarray.com
Solar Engineer




On Sep 14, 2010, at 9:41 AM, Bill Brooks wrote:

> Mark and Rebekah,
>  
> The term “continuous” is a requirement for any circuit and implies electrical continuity and current-carrying capability. Both the GEC and EGC must be continuous or you don’t got one. It is not defined in NEC Article 100.
>  
> What most people are referring to when they say that a GEC must be continuous is “unbroken” or the NEC talks about “irreversibly spliced.” Splicing of a GEC is usually a last resort because there is no other option. For instance, multiple bonding jumpers coming off of multiple inverters would need to be irreversibly spliced to the main GEC that should proceed unbroken from the farthest inverter from the grounding electrode. 250.66 for ac and 250.166 for dc are consistent in requiring the minimum GEC to be 8AWG copper. Since the GEC for Enphase starts at the inverter on the roof, you must have a minimum of 8AWG running among the microinverters and down to the grounding electrode system. In the 2008 NEC and 2011 NEC, this conductor can serve the purpose of the ac EGC as well and can be terminated on the service panel grounding bus.
>  
> Bill.
>  
> From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Rebekah Hren
> Sent: Tuesday, September 14, 2010 7:25 AM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] GEC for Enphase inverters
>  
> The code does require the GEC to be continuous (250.64C), and I believe that the AC EGC for the Enphase metal inverter cases is in fact the same as the DC GEC since the point of system bonding on the DC side is inside the inverter. 
> See art. 100 definitions:Grounding Electrode Conductor. A conductor used to
> connect the system grounded conductor...to a point on the grounding electrode
> 
> system.
> 
> 
> So this means that for Enphase systems the AC EGC (which is also the DC GEC) should be at minimum 8 awg (250.66) and continuous? Seems like it to me. 
>  
> Rebekah Hren
>  
> 
> 
> --- On Tue, 9/14/10, Mark Frye <markf at berkeleysolar.com> wrote:
> 
> From: Mark Frye <markf at berkeleysolar.com>
> Subject: Re: [RE-wrenches] GEC for Enphase inverters
> To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
> Date: Tuesday, September 14, 2010, 10:05 AM
> 
> I believe the AC GEC runs from; the point where the ungrounded current carrying conductor is bonded to the enclosure of the service enterance equipment; to the connection to the ground electrode system. Conductors that run from the service enterance equipment, thru the premis to the Enphase are bonding jumpers that are not required to be continuous.
>  
> Mark Frye 
> Berkeley Solar Electric Systems 
> 303 Redbud Way 
> Nevada City,  CA 95959 
> (530) 401-8024 
> www.berkeleysolar.com 
>  
>  
> From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of William Miller
> Sent: Monday, September 13, 2010 9:46 PM
> To: RE-wrenches
> Subject: [RE-wrenches] GEC for Enphase inverters
> 
> Friends:
> 
> According to the 2005 NEC 250.64(C), the GEC for an AC system needs to be continuous without splices unless they are irreversible.  I am not clear where this conductor starts and ends.  Is it from the ground buss in a sub-panel to the disconnect switch on the roof, or to each inverter?
> 
> Also, non-reversible splices need to be listed for use in grounding systems.  Any suggestions on make and model of splices so listed?
> 
> Any advise from those more experienced is much appreciated.
> 
> William Miller
> 
> Please note new e-mail address and domain:
> 
> William Miller 
> Miller Solar
> Voice :805-438-5600
> email: william at millersolar.com
> http://millersolar.com
> License No. C-10-773985
> 
> 
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