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  • #16
    Originally posted by shortcircuit2 View Post
    My references were to the 2011 NEC

    690.47(D) is gone in 2011
    Does not change a thing, this says it all from 2011:

    690.47 Grounding Electrode System.

    (A) Alternating-Current Systems.
    If installing an ac system,
    a grounding electrode system shall be provided in accordance
    with 250.50 through 250.60. The grounding electrode
    conductor shall be installed in accordance with 250.64.

    (3) Combined Direct-Current Grounding Electrode Conductor
    and Alternating-Current Equipment Grounding
    Conductor.
    An unspliced, or irreversibly spliced, combined
    grounding conductor shall be run from the marked dc grounding
    electrode conductor connection point along with the ac
    circuit conductors to the grounding busbar in the associated ac
    equipment. This combined grounding conductor shall be the
    larger of the sizes specified by 250.122 or 250.166 and shall
    be installed in accordance with 250.64(E).

    The only thing that changed was John Wiles got his wee-wee smacked for allowing separate GES to be used. Now it got corrected to state both AC and DC systems have to use a common GES. To much crap was getting blown up with separate GES, so it got corrected. The GEC to the panel frames and racking are still sized to 250.66. In 250.66 # 8 AWG Cu or #6AWG Alu. However most all installers use #6 AWG copper to take advantage of leniency allowed by:

    250.64 (B) Securing and Protection Against Physical Damage.

    Where exposed, a grounding electrode conductor or its enclosure
    shall be securely fastened to the surface on which it
    is carried. Grounding electrode conductors shall be permitted
    to be installed on or through framing members. A 4
    AWG or larger copper or aluminum grounding electrode
    conductor shall be protected if exposed to physical damage.
    A 6 AWG grounding electrode conductor that is free from
    exposure to physical damage shall be permitted to be run
    along the surface of the building construction without metal
    covering or protection if it is securely fastened to the construction;
    otherwise, it shall be protected in rigid metal
    conduit (RMC), intermediate metal conduit (IMC), rigid
    polyvinyl chloride conduit (PVC), reinforced thermosetting
    resin conduit (RTRC), electrical metallic tubing (EMT), or
    cable armor. Grounding electrode conductors smaller than 6
    AWG shall be protected in RMC, IMC, PVC, RTRC, EMT,
    or cable armor.
    MSEE, PE

    Comment


    • #17
      Well, now I'm totally confused. My inclination is to run my GEC #6 copper to the rails with a WEEB lug and bond the panels and enphase inverter also with a WEEB DMC. Run that down to a grounding rod. Then run the orange Enphase wire along with the two 120vac wires and the common through conduit down to the panel. Connect the enphase orange wire to the bare copper in my panel. Would I be way wrong by doing that?

      Comment


      • #18
        This open dialog is good…This is my interpretation…Per 2011 NEC:


        (3) Combined Direct-Current Grounding Electrode Conductor
        and Alternating-Current Equipment Grounding
        Conductor. An unspliced, or irreversibly spliced, combined
        grounding conductor shall be run from the marked dc grounding
        electrode conductor connection point
        along with the ac
        circuit conductors to the grounding busbar in the associated ac
        equipment. This combined grounding conductor shall be the
        larger of the sizes specified by 250.122 or 250.166 and shall
        be installed in accordance with 250.64(E).

        The “marked dc connection point” is in the inverter, not at the array. This would be at the string inverter when one is used. With Micro-Inverters this would be up at the array…

        Comment


        • #19
          Originally posted by n8huntsman View Post
          Well, now I'm totally confused. My inclination is to run my GEC #6 copper to the rails with a WEEB lug and bond the panels and enphase inverter also with a WEEB DMC. Run that down to a grounding rod. Then run the orange Enphase wire along with the two 120vac wires and the common through conduit down to the panel. Connect the enphase orange wire to the bare copper in my panel. Would I be way wrong by doing that?
          Your method is OK at the rails with the WEEB system as long as the "RAILS" with the "WEEB" are LISTED and approved as OK for grounding the MODULES. Read the module instruction manual to see what is accepted for grounding methods.

          I have not seen an enphase orrange wire. Can you explain this more?

          Comment


          • #20
            HERE IS THE 2005 GEC RULES:

            690.47 Grounding Electrode System
            (A) Alternating-Current Systems If installing an ac system, a grounding electrode
            system shall be provided in accordance with 250.50 through 250.60. The grounding
            electrode conductor shall be installed in accordance with 250.64.
            (B) Direct-Current Systems If installing a dc system, a grounding electrode system shall
            be provided in accordance with 250.166 for grounded systems or 250.169 for ungrounded
            systems. The grounding electrode conductor shall be installed in accordance with 250.64.
            (C) Systems with Alternating-Current and Direct-Current Grounding
            Requirements Photovoltaic power systems with both alternating-current and directcurrent
            (dc) grounding requirements shall be permitted to be grounded as described in (1)
            or (2):

            (1) A grounding-electrode conductor shall be connected between the identified dc
            grounding point
            to a separate dc grounding electrode. The dc grounding-electrode
            conductor shall be sized according to 250.166. The dc grounding electrode shall
            be bonded to the ac grounding electrode to make a grounding electrode system
            according to 250.52 and 250.53. The bonding conductor shall be no smaller than
            the largest grounding electrode conductor, either ac or dc.
            (2) The dc grounding electrode conductor and ac grounding electrode conductor shall
            be connected to a single grounding electrode. The separate grounding electrode
            conductors shall be sized as required by 250.66 (ac) and 250.166 (dc).


            I see no mention of a GEC being needed at an Array for the modules or racking…2005 NEC


            Handbook comments 2005 NEC:

            Inverters used in PV power systems usually contain a transformer that isolates the dc
            grounded circuit conductor from the ac grounded circuit conductor. This isolation
            necessitates that both a dc and an ac grounding system be installed. The two grounding
            systems are to be bonded together or have a common grounding electrode so that all ac
            and dc grounded circuit conductors and equipment grounding conductors have the
            same near-zero potential to earth.


            The GEC to the array was only for the 2008 cycle. Since the NEC isn't a guide for lighting mitigation, the rule was dropped.

            shortcircuit

            Comment


            • #21
              Here is where I was getting orange: http://enphase.com/wp-uploads/enphas...ngle_Phase.pdf
              I assume this is the bare copper wire that would go to the ground in the panel?

              Comment


              • #22
                Originally posted by n8huntsman View Post
                Here is where I was getting orange: http://enphase.com/wp-uploads/enphas...ngle_Phase.pdf
                I assume this is the bare copper wire that would go to the ground in the panel?
                That plan is 4 years old and the orange isn't used. GREEN is for ground here in the States. The most popular Enphase inverter in residential use is the M215 currently and the AC interconnect cable has BLACK, RED, WHITE, and GREEN...no orange that I have seen. The orange may be for 3/phase systems to balance the system.

                Comment


                • #23
                  "Also when you upsize portions of a circuit for voltage drop, you must upsize the equipment grounding conductor also. So just referring to the breaker size, does not always dictate EGC sizing."

                  Wrong again see 690.45 A

                  Naptown..You are right on this one according to the 2011NEC and this was new in 2008 because they realized the fault current is only what is avaiable from the array.

                  In 2005 it was aliitle different...

                  690.45 Size of Equipment Grounding Conductor
                  Where not protected by the ground-fault protection equipment required by 690.5, the
                  equipment-grounding conductor for photovoltaic source and photovoltaic output circuits
                  shall be sized for 125 percent of the photovoltaic-originated short-circuit currents in that
                  circuit. Where protected by the ground-fault protection equipment required by 690.5, the
                  equipment-grounding conductors for photovoltaic source and photovoltaic output circuits
                  shall be sized in accordance with 250.122.

                  But in 2005 you still had to upsize according to 250.122(B)

                  (B) Increased in Size Where ungrounded conductors are increased in size, equipment
                  grounding conductors, where installed, shall be increased in size proportionately
                  according to circular mil area of the ungrounded conductors.

                  Commentary in 2005 NEC:

                  In systems where a ground-fault protection device according to 690.5 is not used, and
                  the circuit conductors are oversized for voltage drop, the requirements of 250.122(B)
                  must be followed.
                  Some PV systems (primarily utility-interactive) with ground-fault protection devices
                  do not require overcurrent devices in the PV source or output circuits, and 250.122
                  cannot be used to size the equipment grounding conductors. In these cases, the
                  equipment grounding conductor for a PV source or output circuit should be sized at
                  least 125 percent of the PV-originated short-circuit current in that circuit.

                  shortcircuit

                  Comment


                  • #24
                    I like pictures. Do you like pictures?

                    I am kind of slow and stupid and I like purty pictures to describe things.

                    MSEE, PE

                    Comment


                    • #25
                      Originally posted by Sunking View Post
                      I like pictures. Do you like pictures?

                      I am kind of slow and stupid and I like purty pictures to describe things.

                      That isn't reflecting what the 2011 or the 2005 NEC says. The diagram also only depicts a system with a isolation type string inverter.

                      Grounding would be different in an ungrounded system connected to a non-isolated type inverter.

                      Comment


                      • #26
                        Originally posted by Sunking View Post
                        I like pictures. Do you like pictures?

                        I am kind of slow and stupid and I like purty pictures to describe things.

                        I wouldn't call it purty but it is very easy to understand. At least I understand

                        Comment


                        • #27
                          So for 2011, we can bring the GEC (#6 typically) into the on roof j-box and attach it to the EGC (green wire) from the enphase cable? Run a single wire back to the panel ground bar.

                          Comment


                          • #28
                            Originally posted by SunEagle View Post
                            I wouldn't call it purty but it is very easy to understand. At least I understand
                            Where is the equipment grounding conductor connection to the array in those diagrams???

                            Comment


                            • #29
                              690.43 says an EGC has to connect to module frames and equipment. This IS in 2005, 2008 and the 2011NEC...

                              Comment


                              • #30
                                Originally posted by n8huntsman View Post
                                So for 2011, we can bring the GEC (#6 typically) into the on roof j-box and attach it to the EGC (green wire) from the enphase cable? Run a single wire back to the panel ground bar.
                                The GEC must continue thru the roof box unbroken to the micro inverters...each one. Or if the racking is listed and approved as suitable for intergrounding with the modules, you can just hit the rails that the inverters are bolted to. If wiring as a combo GEC/EGC you must terminate in the roof box also with the equipment grounds from the Enphase cable. Ferrous raceways must be bonded at both ends. Its not easy when doing it this way.

                                And yes the rule is to bring it back to the panel ground bar when following combo rules. In Mass. the combo rule is not accepted by the CEC FIT program.

                                Comment

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