[RE-wrenches] GEC sizing for a high amp, low voltage PV system with microinverters

[Brian Mehalic]

Sole connection indicates that a GEC is connected to only one type of
grounding electrode. This term is easily mis- understood. For example, a
GEC can be connected to more than one grounding electrode—say, two ground
rods—and still be considered to have a sole connection. Similarly, multiple
GECs connected to the same grounding electrode are each considered to have
a sole connection. When GECs have a sole connection, their maximum size is
limited per NEC Sections 250.66 for an ac system and 250.166 for a dc
system.  The 2014 NEC adds some clarification on this.

Brian Mehalic
NABCEP Certified Solar PV Installation Professional™ R031508-59
IREC ISPQ Certified Affiliated Instructor/PV US-0132

PV Curriculum Developer and Instructor
Solar Energy International
http://www.solarenergy.org


On Wed, Sep 18, 2013 at 4:52 PM, Aladdin Solar <cpickard at aladdinsolar.com>wrote:

> **
> Yes, Jay, this is a TenKSolar system -- they certainly do have a habit of
> taking the 'thinking outside the box' approach!
>
> The microinverter manufacturer states in their installation manual,
> "Connect the grounding electrode conductor to the microinverter ground
> clamp" so it's quite clear we are dealing with GEC rules.
>
> Thanks for all your comments and the reminder of the NEC 250.166(C)
> exception which I hadn't really connected with before.
>
> I'm having difficulty understanding what the requirement in that paragraph
> actually means. When it states "that portion of the grounding electrode
> conductor that is the sole connection to the grounding electrode shall not
> be required to be larger than 6AWG..." -- what does "that portion" and
> "sole connection" mean? If we have a number of GEC branches from that are
> irreversably spliced to a single 6AWG conductor bonded to the grounding
> electrode, do those various GECs affect the "that portion" and "sole
> connection" at all?
>
> Charlie Pickard
> NABCEP Certified PV Installation Professional ™
> Aladdin Solar, LLC
>
>
>
> ----- Original Message -----
> *From:* Bill Brooks <billbrooks7 at yahoo.com>
> *To:* 'RE-wrenches' <re-wrenches at lists.re-wrenches.org>
> *Sent:* Wednesday, September 18, 2013 2:42 PM
> *Subject:* Re: [RE-wrenches] GEC sizing for a high amp,low voltage PV
> system with microinverters
>
>  Nick,****
>
> ** **
>
> Thanks for the clarification—it is a mysterious threaded hole….****
>
> ** **
>
> Bill.****
>
> ** **
>
> *From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
> re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *Nick Soleil
> *Sent:* Wednesday, September 18, 2013 10:19 AM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] GEC sizing for a high amp, low voltage PV
> system with microinverters****
>
> ** **
>
> Hi Bill and wrenches,****
>
> To clarify, our new Enphase M250 microinverter does not have a grounding
> terminal.  The grounding of the M250 will be provided through the Engage
> cable.  We only have a hole in the lid, in the rare case that a lug will be
> desired or required by the AHJ, but we do not provide the grounding clip
> with the microinverter.  A grounding terminal can be added to the
> microinverter.  We have an application note on alternate grounding methods
> for the M250, if needed.****
>
> ** **
>
> ** **
>
>
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