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

[Aladdin Solar]

Thanks Brian. That helps.

Charlie Pickard
NABCEP Certified PV Installation Professional ™
Aladdin Solar,LLC

----- Original Message ----- 
  From: Brian Mehalic 
  To: Aladdin Solar ; RE-wrenches 
  Sent: Wednesday, September 18, 2013 4:17 PM
  Subject: Re: [RE-wrenches] GEC sizing for a high amp, low voltage PV system with microinverters


  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 
      To: 'RE-wrenches' 
      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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