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    Andrew:<br>
    <br>
    I'm confused by your answer about the required additional earth
    connection. That's not described in the Operating Instructions for
    the DGC-1000. Where on the clamp-on meter is the earth connection
    made?<br>
    <br>
    Regards,<br>
    <br>
    Gary Willett<br>
    Icarus Engineering LLC<br>
    <div class="moz-forward-container"><br>
      <br>
      -------- Original Message --------
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            <th align="RIGHT" nowrap="nowrap" valign="BASELINE">Subject:
            </th>
            <td>Re: [RE-wrenches] EGC ground impedance</td>
          </tr>
          <tr>
            <th align="RIGHT" nowrap="nowrap" valign="BASELINE">Date: </th>
            <td>Wed, 15 Jan 2014 15:32:23 +0000</td>
          </tr>
          <tr>
            <th align="RIGHT" nowrap="nowrap" valign="BASELINE">From: </th>
            <td>Andrew Truitt <a class="moz-txt-link-rfc2396E" href="mailto:atruitt@gmail.com"><atruitt@gmail.com></a></td>
          </tr>
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            <th align="RIGHT" nowrap="nowrap" valign="BASELINE">Reply-To:
            </th>
            <td>RE-wrenches <a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a></td>
          </tr>
          <tr>
            <th align="RIGHT" nowrap="nowrap" valign="BASELINE">To: </th>
            <td>RE-wrenches <a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a></td>
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      <br>
      <div dir="ltr"><br>
        <div>Bill - Ray (the owner of this tool) just explained to me
          that in order for it to function properly it needs an
          additional connection to earth to complete the circuit.  I.e.,
          my issue stems from user error.  Thanks for the help Ray!
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                                <p class="MsoNormal"><span
                                    style="color:rgb(56,118,29)">For a
                                    brighter energy future,<br>
                                    <br>
                                    <br>
                                    Andrew Truitt <br>
                                  </span></p>
                              </div>
                              <div>
                                <p class="MsoNormal"><span
                                    style="color:rgb(56,118,29)">Principal<br>
                                    Truitt Renewable Energy </span><span
                                    style="color:rgb(56,118,29)">Consulting,
                                    LLC</span></p>
                              </div>
                              <div>
                                <p class="MsoNormal"><span
                                    style="color:rgb(56,118,29)"><a
                                      moz-do-not-send="true"
                                      href="tel:%28202%29%20486-7507"
                                      value="+12024867507"
                                      target="_blank">(202) 486-7507</a></span></p>
                                <p class="MsoNormal"><a
                                    moz-do-not-send="true"
                                    href="http://www.linkedin.com/pub/andrew-truitt/8/622/713"
                                    target="_blank">LinkedIn Profile</a></p>
                                <p class="MsoNormal"><a
                                    moz-do-not-send="true"
                                    href="http://truittreconsulting.weebly.com/"
                                    target="_blank">Company Website<span><span></span></span></a></p>
                                <p class="MsoNormal"><span
                                    style="color:rgb(56,118,29)"><span>NABCEP</span>
                                    Certified PV Installation
                                    Professional ID: 032407-66</span></p>
                                <p class="MsoNormal"><span
                                    style="color:rgb(56,118,29)">Colorado
                                    Journeyman Electrician License No.:
                                    600132</span><br>
                                </p>
                                <p class="MsoNormal">
                                  <span style="color:rgb(0,102,0)"><a
                                      moz-do-not-send="true"
                                      href="tel:%28202%29%20486-7507"
                                      target="_blank"><span
                                        style="color:rgb(17,85,204)"></span></a></span></p>
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                          <p><span style="color:rgb(20,125,186)"></span><span
                              style="color:rgb(20,125,186)"><img
                                src="cid:part5.07020300.04000707@IcarusSolarServices.com"
                                alt="24 copy.jpg" border="0"
                                height="133" width="200"></span><br>
                            <span style="color:rgb(20,125,186)"><br>
                            </span>"Don't get me wrong: I love nuclear
                            energy! It's just that I prefer fusion to
                            fission. And it just so happens that there's
                            an enormous fusion reactor safely banked a
                            few million miles from us. It delivers more
                            than we could ever use in just about 8
                            minutes. And it's wireless!"<br>
                            <br>
                            ~William McDonough</p>
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        <br>
        <div class="gmail_quote">On Wed, Jan 15, 2014 at 4:54 AM, Andrew
          Truitt <span dir="ltr"><<a moz-do-not-send="true"
              href="mailto:atruitt@gmail.com" target="_blank">atruitt@gmail.com</a>></span>
          wrote:<br>
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">
            <div dir="ltr">Bill - I'm using an Amprobe DGC-1000A.  I let
              it self-calibrate and then simply clamp it on to a
              conductor, and it reads the impedance to ground (<a
                moz-do-not-send="true"
                href="http://content.amprobe.com/manualsA/DGC1000.pdf"
                target="_blank">http://content.amprobe.com/manualsA/DGC1000.pdf</a>).
               I used it on a well grounded RBI system (driven piles) a
              few months ago and it measured ground impedances of less
              than 25 Ohms for all EGCs, as expected for a system with
              so much contact between the metal structure and earth.
              <div>
                <br>
              </div>
              <div>Ray - The tray does make a good conductor.  I did
                some more testing and any point along the tray itself
                gives less than 10 Ohms; its only the #10 conductors
                between the array and the tray where the impedance
                spikes.  The conductors are bonded to the tray with
                torqued, star-washered, copper/stainless lay-in lugs.
                 There are no ground rods in the system due to the
                requirements of the capped landfill, but there is a UFER
                ground at the equipment pad that gives readings of <
                1 Ohm for the GEC.</div>
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                                        <p class="MsoNormal">
                                          <span
                                            style="color:rgb(56,118,29)">For
                                            a brighter energy future,<br>
                                            <br>
                                            <br>
                                            Andrew Truitt <br>
                                          </span></p>
                                      </div>
                                      <div>
                                        <p class="MsoNormal"><span
                                            style="color:rgb(56,118,29)">Principal<br>
                                            Truitt Renewable Energy </span><span
                                            style="color:rgb(56,118,29)">Consulting,
                                            LLC</span></p>
                                      </div>
                                      <div>
                                        <p class="MsoNormal"><span
                                            style="color:rgb(56,118,29)"><a
                                              moz-do-not-send="true"
                                              href="tel:%28202%29%20486-7507"
                                              value="+12024867507"
                                              target="_blank">(202)
                                              486-7507</a></span></p>
                                        <p class="MsoNormal"><a
                                            moz-do-not-send="true"
                                            href="http://www.linkedin.com/pub/andrew-truitt/8/622/713"
                                            target="_blank">LinkedIn
                                            Profile</a></p>
                                        <p class="MsoNormal"><a
                                            moz-do-not-send="true"
                                            href="http://truittreconsulting.weebly.com/"
                                            target="_blank">Company
                                            Website<span><span></span></span></a></p>
                                        <p class="MsoNormal"><span
                                            style="color:rgb(56,118,29)"><span>NABCEP</span>
                                            Certified PV Installation
                                            Professional ID: 032407-66</span></p>
                                        <p class="MsoNormal"><span
                                            style="color:rgb(56,118,29)">Colorado
                                            Journeyman Electrician
                                            License No.: 600132</span><br>
                                        </p>
                                        <p class="MsoNormal">
                                          <span
                                            style="color:rgb(0,102,0)"><a
                                              moz-do-not-send="true"
                                              href="tel:%28202%29%20486-7507"
                                              target="_blank"><span
                                                style="color:rgb(17,85,204)"></span></a></span></p>
                                      </div>
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                                  <p><span style="color:rgb(20,125,186)"></span><span
                                      style="color:rgb(20,125,186)"><img
src="cid:part5.07020300.04000707@IcarusSolarServices.com" alt="24
                                        copy.jpg" border="0"
                                        height="133" width="200"></span><br>
                                    <span style="color:rgb(20,125,186)"><br>
                                    </span>"Don't get me wrong: I love
                                    nuclear energy! It's just that I
                                    prefer fusion to fission. And it
                                    just so happens that there's an
                                    enormous fusion reactor safely
                                    banked a few million miles from us.
                                    It delivers more than we could ever
                                    use in just about 8 minutes. And
                                    it's wireless!"<br>
                                    <br>
                                    ~William McDonough</p>
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                <div class="gmail_extra"><br>
                  <br>
                  <div class="gmail_quote">
                    <div>
                      <div class="h5">On Tue, Jan 14, 2014 at 10:47 PM,
                        Bill Brooks <span dir="ltr"><<a
                            moz-do-not-send="true"
                            href="mailto:billbrooks7@yahoo.com"
                            target="_blank">billbrooks7@yahoo.com</a>></span>
                        wrote:<br>
                      </div>
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                    <blockquote class="gmail_quote" style="margin:0px
                      0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
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                                <span
style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Andy,</span></p>
                              <p class="MsoNormal"><span
style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"> </span></p>
                              <p class="MsoNormal"><span
style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">How
                                  are you testing the ground impedance
                                  of the EGC?</span></p>
                              <p class="MsoNormal"><span
style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"> </span></p>
                              <p class="MsoNormal"><span
style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Bill.</span></p>
                              <p class="MsoNormal"><span
style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"> </span></p>
                              <p class="MsoNormal"><b><span
                                    style="font-size:11pt;font-family:Calibri,sans-serif">From:</span></b><span
style="font-size:11pt;font-family:Calibri,sans-serif"> <a
                                    moz-do-not-send="true"
                                    href="mailto:re-wrenches-bounces@lists.re-wrenches.org"
                                    target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a>
                                  [mailto:<a moz-do-not-send="true"
                                    href="mailto:re-wrenches-bounces@lists.re-wrenches.org"
                                    target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a>]
                                  <b>On Behalf Of </b>Andrew Truitt<br>
                                  <b>Sent:</b> Tuesday, January 14, 2014
                                  7:25 AM<br>
                                  <b>To:</b> RE-wrenches<br>
                                  <b>Subject:</b> [RE-wrenches] EGC
                                  ground impedance</span></p>
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                                    <p class="MsoNormal">
                                      Wrenches - What do you consider to
                                      be a safe ground impedance for a
                                      PV array equipment grounding
                                      conductor?  NEC2011 250.53(A) says
                                      that if the impedance between the
                                      grounding <i>electrode</i> and
                                      earth is less than 25 ohms then no
                                      supplementary grounding electrode
                                      is needed, but I'm not clear on
                                      what that means for the ground
                                      impedance measurement within the
                                      array.  For example, I am
                                      inspecting a ballasted landfill
                                      system (i.e. no penetrating the
                                      earth allowed - just a UFER at the
                                      equipment pad) where the ground
                                      impedance at the GEC is very low
                                      (<1 Ohm), but the array EGCs
                                      are showing ground impedances of
                                      between 500 and 1000 Ohms.  The
                                      EGCs (#4) are connected to Cope
                                      cable trays, which are in turn
                                      connected to the inverter
                                      grounding bar via #4 bonding
                                      jumpers.  The cable tray is
                                      grounded per manufacturer specs
                                      (large bonding jumpers at each
                                      joint), but the runs can be quite
                                      long (300'+) with many
                                      connections, though nothing
                                      appears to be loose.  I intend to
                                      recommend that continuous
                                      conductors be installed to reduce
                                      array ground impedance, but any
                                      input on the issue would be very
                                      much appreciated.</p>
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                                                          <p
                                                          class="MsoNormal"><span
style="color:rgb(56,118,29)">For a brighter energy future,<br>
                                                          <br>
                                                          <br>
                                                          Andrew Truitt </span></p>
                                                        </div>
                                                        <div>
                                                          <p
                                                          class="MsoNormal"><span
style="color:rgb(56,118,29)">Principal<br>
                                                          Truitt Renewable Energy Consulting,
                                                          LLC</span></p>
                                                        </div>
                                                        <div>
                                                          <p
                                                          class="MsoNormal">
                                                          <span
                                                          style="color:rgb(56,118,29)"><a
moz-do-not-send="true" href="tel:%28202%29%20486-7507" target="_blank">(202)
                                                          486-7507</a></span></p>
                                                          <p
                                                          class="MsoNormal"><a
moz-do-not-send="true"
                                                          href="http://www.linkedin.com/pub/andrew-truitt/8/622/713"
target="_blank">LinkedIn Profile</a></p>
                                                          <p
                                                          class="MsoNormal"><a
moz-do-not-send="true" href="http://truittreconsulting.weebly.com/"
                                                          target="_blank">Company
                                                          Website</a></p>
                                                          <p
                                                          class="MsoNormal"><span
style="color:rgb(56,118,29)">NABCEP Certified PV Installation
                                                          Professional
                                                          ID: 032407-66</span></p>
                                                          <p
                                                          class="MsoNormal"><span
style="color:rgb(56,118,29)">Colorado Journeyman Electrician License
                                                          No.: 600132</span></p>
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                                                    <p><span
                                                        style="color:rgb(20,125,186)"><img
src="cid:part19.07030304.05060101@IcarusSolarServices.com" alt="24
                                                          copy.jpg"
                                                          border="0"
                                                          height="133"
                                                          width="200"></span><br>
                                                      <span
                                                        style="color:rgb(20,125,186)"><br>
                                                      </span>"Don't get
                                                      me wrong: I love
                                                      nuclear energy!
                                                      It's just that I
                                                      prefer fusion to
                                                      fission. And it
                                                      just so happens
                                                      that there's an
                                                      enormous fusion
                                                      reactor safely
                                                      banked a few
                                                      million miles from
                                                      us. It delivers
                                                      more than we could
                                                      ever use in just
                                                      about 8 minutes.
                                                      And it's
                                                      wireless!"<br>
                                                      <br>
                                                      ~William McDonough</p>
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