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.
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.
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.
Don Barch
Energy Solar
-------- Original Message --------
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Message: 1
Date: Wed, 2 Apr 2014 17:20:36 -0500
From: "Garrison Riegel" <garri...@solarserviceinc.com>
To: "'RE-wrenches'" <re-wrenches@lists.re-wrenches.org>
Subject: [RE-wrenches] Three Inverters, One Disconnect?
Message-ID: <817a01cf4ec1$c5d8ad00$518a0700$@solarserviceinc.com>
Content-Type: text/plain; charset="us-ascii"
Hello Wrenches,
On an upcoming project we are interconnecting (3) Power-One, ahem, ABB PVI
3.6 inverters to a 3Ph 277/480V service. Each inverter output is 16A at
277V, 1Ph. Is it code compliant to run the single phase output of each
inverter to a single pole of a 3-pole [utility required] AC disconnect
before landing at each 1-pole 20A breaker in the main panel? It would be
great to avoid an inverter subpanel and 3-pole breaker in the MDP if
possible.
Thanks for your thoughts.
Garrison
Garrison Riegel
Project Manager | <http://www.solarserviceinc.com/> Solar Service Inc
[p] 847-677-0950 | <mailto:garri...@solarserviceinc.com>
garri...@solarserviceinc.com
NABCEP Certified PV Installation ProfessionalT
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