<html><body><span style="font-family:Verdana; color:#000000; font-size:10pt;"><div>Hi Garrison- The dedicated breaker referred to in 705.12(D)(1) means they do not want the inverters plugged into branch breakers. One (and only one) inverter into each pole of a 3-pole breaker seems safer and better than 3 individual breakers, and seems to fit the definition of "dedicated" breaker.</div><div>I don't know that you can even find single-pole 277 Vac breakers....<br></div><div>DonB<br></div>
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Message: 6<br>
Date: Fri, 4 Apr 2014 08:01:00 -0500<br>
From: "Garrison Riegel" <<a href="mailto:garrison@solarserviceinc.com">garrison@solarserviceinc.com</a>><br>
To: <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><br>
Subject: Re: [RE-wrenches] Three Inverters, One Disconnect?<br>
Message-ID: <828201cf5005$edd065b0$c9713110$@<a href="http://solarserviceinc.com" mce_href="http://solarserviceinc.com">solarserviceinc.com</a>><br>
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Hi Don,<br>
<br>
Thank you for your reply. Good idea on the single 480V inverter, but multiple subarrays at different tilts/orientations and strings lengths make that impractical unfortunately. <br>
<br>
It also seems like a good idea to use a single 3-pole breaker to prevent phase imbalance, but I thought each inverter required a dedicated breaker as per 705.12(D)(1). Thoughts?<br>
<br>
Thanks,<br>
<br>
Garrison<br>
<br>
From: <a href="mailto:don@energysolarnow.com">don@energysolarnow.com</a> [<a href="mailto:don@energysolarnow.com">mailto:don@energysolarnow.com</a>] <br>
Sent: Thursday, April 03, 2014 1:55 PM<br>
To: <a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>; Garrison Riegel<br>
Subject: RE: [RE-wrenches] Three Inverters, One Disconnect?<br>
<br>
With single phase 240 each inverter output is two poles; but since you are using 277 each inverter output is between one pole and neutral, so you could indeed use a 3-pole disconnect since the neutrals are not switched.<br>
<br>
A 3-pole breaker is usually used with 3-phase systems, but since there are 3 separate inverters it is legal to use 3 single pole breakers provided you get them into separate phase poles. However, there would be a phase imbalance if one breaker tripped and the others were still sourcing current, so it's better to use a 3-pole breaker here. <br>
<br>
But rather than go to all the work of wiring 3 separate 3.6 kW inverters, why not just use the PowerOne 10.0 or 12.0 kW 3-phase inverters? This would be less expensive and would need just one conduit run for input and output.<br>
<br>
Don Barch<br>
<br>
Energy Solar<br>
<br>
<br>
<br>
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Message: 1<br>
Date: Wed, 2 Apr 2014 17:20:36 -0500<br>
From: "Garrison Riegel" <<a href="mailto:garrison@solarserviceinc.com">garrison@solarserviceinc.com</a> ><<a href="mailto:garrison@solarserviceinc.com">mailto:garrison@solarserviceinc.com</a>> ><br>
To: "'RE-wrenches'" <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a> ><<a href="mailto:re-wrenches@lists.re-wrenches.org">mailto:re-wrenches@lists.re-wrenches.org</a>> ><br>
Subject: [RE-wrenches] Three Inverters, One Disconnect?<br>
Message-ID: <817a01cf4ec1$c5d8ad00$518a0700$@<a href="http://solarserviceinc.com" mce_href="http://solarserviceinc.com">solarserviceinc.com</a> ><http://<a href="http://solarserviceinc.com" mce_href="http://solarserviceinc.com">solarserviceinc.com</a>> ><br>
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Hello Wrenches,<br>
<br>
On an upcoming project we are interconnecting (3) Power-One, ahem, ABB PVI<br>
3.6 inverters to a 3Ph 277/480V service. Each inverter output is 16A at<br>
277V, 1Ph. Is it code compliant to run the single phase output of each<br>
inverter to a single pole of a 3-pole [utility required] AC disconnect<br>
before landing at each 1-pole 20A breaker in the main panel? It would be<br>
great to avoid an inverter subpanel and 3-pole breaker in the MDP if<br>
possible.<br>
<br>
Thanks for your thoughts.<br>
<br>
Garrison<br>
<br>
Garrison Riegel<br>
<br>
Project Manager | <http://www.<a href="http://solarserviceinc.com" mce_href="http://solarserviceinc.com">solarserviceinc.com</a> ><http://<a href="http://solarserviceinc.com" mce_href="http://solarserviceinc.com">solarserviceinc.com</a>> /> Solar Service Inc<br>
<br>
[p] 847-677-0950 | <<a href="mailto:garrison@solarserviceinc.com">mailto:garrison@solarserviceinc.com</a>><br>
<a href="mailto:garrison@solarserviceinc.com">garrison@solarserviceinc.com</a> <<a href="mailto:garrison@solarserviceinc.com">mailto:garrison@solarserviceinc.com</a>> <br>
<br>
NABCEP Certified PV Installation ProfessionalT<br>
<br>
<br>
<br>
<br>
</div>
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