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<DIV><FONT size=2 face=Arial>We will be installing a 40KW grid-tied PV system
that uses PV modules wired in parallel as per the module manufacturer -- so
it's a high amperage, low voltage system on the DC side. 2 branches of about 3KW
of parallel wired modules each come together onto a DC bus. The DC branch
conductors are sized as 2AWG.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The inverter system provided by the manufacturer
consists of a number of UL1741 single phase microinverters that all are powered
off of the low voltage DC bus. So there's a bunch of microinverters in parallel,
combined output is single phase power.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Those microinverters have a ground lug labeled
"GEC". You know where this is going...</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Assuming we are following NEC 690.47(C)(3), we'll
be treating this ground as GEC and following all the GEC rules. My
understanding is that because the DC conductors within the array are 2AWG (NEC
250.166(B), we will need to connect all 12 branches and 6 DC buses with
continuous 2AWG and bring it all the way back 300' to where the AC GEC bond is
located. We're getting a lot of pushback from the electrical sub and even some
disagreement from the module manufacturer on this--no one's ever seen a
grounding conductor of this size being required for this
application.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Please don't get too bogged down with understanding
the low voltage, parallel module spec and the massive number of microinverters
involved. What I'm looking for is confirmation that I am properly
understanding how the NEC GEC requirements apply, especially to the
GEC size.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Charlie Pickard<BR>NABCEP Certified PV Installation
Professional ™<BR>Aladdin Solar, LLC<BR></FONT></DIV><BR>
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