Doug, 705.95(B) allows you down size your neutral if it is used solely for instrumentation and it must be sized equal to or larger than the EGC but this is not the case. If Power One says a full size neutral is needed than that means that it is not just a voltage sensing conductor used for instrumentation and that it does carry current.
I don't believe there are any exceptions in code for downsizing your neutral in regards to upsizing the conductors to account for voltage drop but I could be wrong. -- John Stimac | Corvallis, OR Renewable Energy Associates LLC 541-754-2001 Office/Fax j...@renewableassociates.com www.renewableassociates.com <http://www.renewableassociates.com/> REAL_logo_black2 From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Drake Sent: Wednesday, June 19, 2013 6:42 To: re-wrenches@lists.re-wrenches.org Subject: [RE-wrenches] Full sized neutral - 240 V inverter Hello Wrenches, Power One tech support said that full sized neutrals had to be run to a pair of 240 V, PVI 3.6 inverters. We have a 180 foot underground run to the service panel. Why do we need to run a full sized neutral all the way back to the panel? The wiring to the panel is oversized for voltage drop. The code allows for reduction of neutral size where neutral imbalance is less than the current of a phase, which is usually the case. Why does a neutral need to be installed that is the size of the phase wiring where the imbalance should be negligible? Or is there a lot of neutral current for some reason? Am I missing something? Thanks Drake Drake Chamberlin Athens Electric LLC OH License 44810 CO License 3773 NABCEP Certified Solar PV Installer 740-448-7328 http://athens-electric.com/
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