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Phil,<br>
<br>
While using a dual GFDI to open both positive and negative array
conductors is the safest thing to do in battery systems, and it is
clearly compliant with 690.5 to do so, it is not consistent with the
manufacturer's instructions or the device listing. So that leads
back to a violation of 110.3(B). I find the present situation very
disturbing.<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 4/18/2012 8:28 PM, Philip wrote:
<blockquote
cite="mid:833BC721-4252-4F01-850B-755C8FA4645F@gmail.com"
type="cite">
<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
moz-do-not-send="true" href="mailto:kent@coveoregon.com">kent@coveoregon.com</a>>
wrote:<br>
<br>
</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 moz-do-not-send="true" 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>
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