[RE-wrenches] Full sized neutral - 240 V inverter

[John Stimac]

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

john at renewableassociates.com

www.renewableassociates.com <http://www.renewableassociates.com/> 

REAL_logo_black2

 

 

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Drake
Sent: Wednesday, June 19, 2013 6:42
To: re-wrenches at 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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