<html><head></head><body bgcolor="#FFFFFF"><div>Hi Kent, </div><div><br></div><div>I wanted to add a little more re positive grounding. OutBack's communication structure, like many other manufacturers, is referenced to Negative. If you install multiple devices in a positive ground system and connect them together via a Hub and add disconnects/overcurrent protection like normal in the ungrounded (this time negative) conductor, any time the breaker opens current will try to return to the battery by any means possible, and that means through the comm cables. That pretty much takes out all the connected devices, it aint pretty. Therefore, OutBack recommends using double pole breakers, in both positive and negative conductors, when using multiple connected current-generation devices in positive grounded systems. Not a perfect solution, but it is what it is. </div><div><br></div><div>To answer your question about upgrading older systems, if I were working on my mother's house and I had the option, I would not install any of the current generation GFDI devices. That might be heresy and not technically Code compliant, but on a battery based system I believe it to be the safer option. If I had to install one, it could go on either the battery or the array side of the controller. Once there is a better solution I would go back and retrofit Mom's system, because it's worth it. </div><div><br></div><div>BTW, OutBack's double and quad GFDI can be used to simultaneously disconnect both positive and negative, per your desire. That's another advantage of a multi-pole device. </div><div><br></div><div>Phil<br><br><br><div><br></div></div><div><br>On Apr 18, 2012, at 2:21 PM, Kent Osterberg <<a href="mailto:kent@coveoregon.com">kent@coveoregon.com</a>> wrote:<br><br></div><div></div><blockquote type="cite"><div>
<meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type">
William,<br>
<br>
Square D used to make a QO breaker body without the overcurrent trip
mechanism. Internally it just had the switch contacts and it was
intended for use as a disconnect in locations where overcurrent
protection was already provided. The reason I mention this is that
the 80-amp PV GFP should not be thought of as overcurrent
protection. In fact it would be most appropriate if the 80-amp side
of the GFP didn't have an overcurrent trip mechanism. It <i>should</i>
only be sensitive to ground faults. If it is sensitive to
overcurrent, then it may be activated when there isn't a ground
fault and unnecessarily disconnect the negative conductor from
ground. <br>
<br>
Code prohibits the use of a GFP as a disconnect for the PV array. I
believe that's because they intend the power system to remain bonded
to ground except in the event of ground fault. It follows that the
GFP should not be used as a disconnect between the batteries and
charge controller either. That's my interpretation. The Code doesn't
mention the possibility of putting the GFP between the batteries and
charge controller as Outback's instructions for the GFDI require.
So, even though Outback's instructions for the GFDI don't show it,
put an appropriate breaker for overcurrent protection between the
battery and the GFDI, then use wire that's appropriate for the
charge controller and overcurrent protection. <br>
<br>
In my opinion putting the GFDI between the batteries and charge
controller is a really bad idea. Nearly all charge controllers warn
that the battery should be turned on first and turned off last. It
puts much more stress on the charge controller when the battery
circuit is opened under load than it does when the PV circuit is
opened. In fact opening the battery circuit may well cause the
charge controller to fail. Outback warns that if their charge
controllers are connected to a positive ground system, the
communication port of the charge controller or the Hub may be
damaged. If there is a fault in the PV array that causes the GFDI to
open, it very well may leave the system in a positive ground
condition. <br>
<br>
When upgrading an older PSDC Outback system which instructions are
more appropriate to follow? The ones for the PSDC that show the GFP
before the charge controller. Or the newer instructions for the GFDI
that show it after the charge controller. Except the the label and
instructions the GFP and the GFDI are identical. In case you don't
remember, the PSDC came with a schematic showing all possible
options attached to the back of the front panel. When it comes time
to troubleshoot sometime in the future, that schematic is still
going to be there.<br>
<br>
<pre class="moz-signature" cols="72">Kent Osterberg
Blue Mountain Solar, Inc.
<a class="moz-txt-link-abbreviated" href="http://www.bluemountainsolar.com">www.bluemountainsolar.com</a>
t: 541-568-4882</pre>
<br>
On 4/17/2012 6:42 PM, William Miller wrote:
<blockquote cite="mid:6.0.1.1.2.20120417180352.02904358@millersolar.com" type="cite">
Friends:<br>
<br>
Here is a related problem: If we use an 80 amp GFD (ground fault
detection) breaker, even for a very small array, we have to use
3AWG CU
wire from the battery buss to the breaker and from the breaker to
the FM
or MX60. This seems like a big hassle for 5 or 10 amps of
charging. A variety of sizes of GFD breakers would be
helpful.<br>
<br>
Here is a bigger problem: GFD breakers don't really work. All
they do is turn off the charge function in hopes that someone will
find
the problem. In the meantime, the negative-to-ground bond is
removed and module mounting framework could be energized. PV GFD
breakers are completely different from standard AC GFDI (ground
fault
detection and interruption) receptacles and circuit breakers. The
AC versions interrupt power upstream, the PV versions interrupt
power
<i>downstream</i> from the fault.<br>
<br>
See:
<a moz-do-not-send="true" href="http://millersolar.com/MillerSolar/case_studies/ground_fauilt/_ground_fault.html" eudora="autourl">http://millersolar.com/MillerSolar/case_studies/ground_fauilt/_ground_fault.html</a>
for some musings on the subject.<br>
<br>
As they say on TV: "There had to be a better way!"<br>
<br>
William Miller<br>
<br>
<br>
<br>
<br>
<br>
At 05:54 PM 4/17/2012, Kent Osterberg wrote:<br>
<blockquote type="cite" class="cite" cite="">Nathan,<br>
<br>
I don't think anyone makes a 100-amp PV GFP. The panel mount
breaker model that's being used for the PV GFP doesn't include a
100-amp breaker.<br>
<br>
The Classic has a built-in GFP so you shouldn't need an external
GFP for it. You will need to add a GFP for the FM60 - a single
80-amp GFP would work.<br>
<br>
You can use the dual 80-amp GFP and shut down both PV arrays at
the same time if the GFP is wired to disconnect the PV array
from the charge controller input. That's where Outback's
instructions used to show the GFP, and it is a better place for
it than on the charge controller output anyway. Midnite's
instructions show the GFP on the charge controller input, but
their 80-amp GFP is a single.<br>
<br>
<pre>Kent Osterberg
Blue Mountain Solar, Inc.
<a moz-do-not-send="true" href="http://www.bluemountainsolar.com">www.bluemountainsolar.com</a>
</pre>
<br>
On 4/17/2012 11:08 AM, Nathan Stumpff wrote: <br>
<blockquote type="cite" class="cite" cite="">Wrenches,<br>
<br>
In a job coming up I have a customer with an existing FM60
controller, 520 watt (!!) array. We are doing a ton of work,
including adding a 4 kW solar array with Classic 150 charge
controller. I am trying to figure out how to handle the GFP.<br>
<br>
For the Classic, I need a 90 or 100 A output breaker minimum.
80 A is not an option. The OutBack dual GFP is 80 A, and so it
not an option.<br>
<br>
Is there a 100 A GFP breaker assembly I have just never seen?
Is there a way to use the Classic’s GFP to run an external
relay via AUX (to trip the FM60 output breaker at the same
time)? Any ideas?<br>
<br>
Thanks,<br>
-Nathan<br>
<br>
--<br>
Nathan J. Stumpff - Arctic Sun, LLC<br>
NABCEP Ceritified PV Installer #091209-175<br>
<a moz-do-not-send="true" href="mailto:nathan@arcticsun-llc.com">nathan@arcticsun-llc.com</a><br>
Office: 907/457-1297<br>
</blockquote>
_______________________________________________<br>
List sponsored by Home Power magazine<br>
<br>
List Address: <a class="moz-txt-link-abbreviated" href="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</a><br>
<br>
Options & settings:<br>
<a moz-do-not-send="true" href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" eudora="autourl">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a><br>
<br>
List-Archive: <a moz-do-not-send="true" href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org" eudora="autourl">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><br>
<br>
List rules & etiquette:<br>
<a moz-do-not-send="true" href="http://www.re-wrenches.org/etiquette.htm" eudora="autourl">www.re-wrenches.org/etiquette.htm</a><br>
<br>
Check out participant bios:<br>
<a moz-do-not-send="true" href="http://www.members.re-wrenches.org/" eudora="autourl">www.members.re-wrenches.org</a><br>
<br>
<br>
No virus found in this incoming message.<br>
Checked by AVG - <a moz-do-not-send="true" href="http://www.avg.com/" eudora="autourl">www.avg.com</a> <br>
Version: 8.5.455 / Virus Database: 271.1.1/4341 - Release Date:
04/16/12 18:34:00</blockquote>
<x-sigsep>
<p>Miller Solar<br>
Voice :805-438-5600<br>
email: <a class="moz-txt-link-abbreviated" href="mailto:william@millersolar.com">william@millersolar.com</a><br>
<a moz-do-not-send="true" href="http://millersolar.com/" eudora="autourl">http://millersolar.com<br>
</a>License No. C-10-773985<br>
<br>
</p>
<fieldset class="mimeAttachmentHeader"></fieldset>
</x-sigsep></blockquote>
</div></blockquote><blockquote type="cite"><div><span>_______________________________________________</span><br><span>List sponsored by Home Power magazine</span><br><span></span><br><span>List Address: <a href="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</a></span><br><span></span><br><span>Options & settings:</span><br><span><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a></span><br><span></span><br><span>List-Archive: <a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a></span><br><span></span><br><span>List rules & etiquette:</span><br><span><a href="http://www.re-wrenches.org/etiquette.htm">www.re-wrenches.org/etiquette.htm</a></span><br><span></span><br><span>Check out participant bios:</span><br><span><a href="http://www.members.re-wrenches.org">www.members.re-wrenches.org</a></span><br><span></span><br></div></blockquote></body></html>