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<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial>William,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial>Put the inverters at the array. Run the AC underground.
If the AC feeder gets dug up by some rowdy backhoe operator in
the future, the breaker (or series of breakers) will open, de-energizing the
circuit immediately (and maybe the main to the residence at the same
time).</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial>If you are dead-set on putting the inverters in the pump shed,
put any combiner(s) at the inverters. This affords the maximum overcurrent
protection for the underground feeders. Install DC disconnecting means in each
string before leaving the array if you go this route.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial>For maximum protection of conductors and to minimize arc
hazards, </FONT></SPAN><SPAN class=765255823-20122009><FONT color=#0000ff size=2
face=Arial>The SAFEST location for a combiner is ALWAYS at the inverter.
All conductors on the inverter (load) side of a fused combiner are unprotected
by anything other than their ampacity rating. If a fault occurs on the load side
of a combiner, it will burn until it clears or welds to a dead short.
</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN><SPAN class=765255823-20122009><FONT
color=#0000ff size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial>Cheers,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=765255823-20122009><FONT color=#0000ff
size=2 face=Arial>Matt Lafferty</FONT></SPAN></DIV>
<DIV class=Section1><STRONG><EM><FONT
face="Monotype Corsiva"></FONT></EM></STRONG><BR> </DIV>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B> re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of </B>William
Miller<BR><B>Sent:</B> Sunday, December 20, 2009 11:02 AM<BR><B>To:</B>
RE-wrenches<BR><B>Subject:</B> [RE-wrenches] DC disconnect
placement<BR></FONT><BR></DIV>
<DIV></DIV>Friends:<BR><BR>I am embarking on a 10 Kw ground mount grid-tie
installation. The client prepared for this installation some time ago by
stubbing a PVC conduit underground towards the future location of the PV
array. Prior to beginning this job, an excavation contractor intercepted
the empty conduit with a backhoe.<BR><BR>No harm was done because this conduit
was empty. Had this conduit been filled with PV feeders, it would have
been very necessary to be able to disconnect the PV arrays, both for safety and
to prevent a brush fire in our very dry climate.<BR><BR>The inverters will be
located in a pump house about 130 feet from the PV arrays. I would not
normally put disconnects at the array and they are not required. This
scenario, however, has caused me to reconsider. The design now calls for a
disconnect at each row of modules. I feel that it would not be prudent to
delete this important safety item.<BR><BR>I wish there were a better selection
of compact, low profile disconnects suitable for a roof-top
installation. I have put external handle disconnects on roof but they look
terrible. I may specify touch-safe fuse holders inside of a Sola Deck for
future comp roof jobs. I am not sure what we will do with tile
roofs.<BR><BR>It seems to me that every source of power should have a means of
disconnection as close to the source as possible. This is just common
sense.<BR><BR>William Miller<BR><BR><X-SIGSEP>
<P></X-SIGSEP><FONT size=3><U>Please note new e-mail address and
domain:<BR><BR></U>William Miller <BR>Miller Solar<BR>Voice
:805-438-5600<BR>email: william@millersolar.com<BR><A
href="http://millersolar.com/"
eudora="autourl">http://millersolar.com<BR></A>License No.
C-10-773985<BR></FONT></P></BODY></HTML>