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

Thu Jun 20 13:18:14 PDT 2013

Hi Wallace,

For services, at least, in the 2011 NEC, the neutral is still sized 
per Table 250.66 (250.24 (C) (1).

I took Allan's suggestion and called Power One tech support back. The 
neutral carries no current; it is strictly for sensing.

Drake

At 02:23 PM 6/20/2013, you wrote:
>Drake,
>
>Full sized neutrals are now required due to harmonics at least.
>
>The cost over your quote for neutral is fixed. What is the cost for 
>unknown consequences if you disregard manufacturers specs?
>
>Wallace Stahle
>Future Electric Energy Co
>P O Box 236
>Willits, CA 95490
><mailto:future at pacific.net>future at pacific.net
>CA Lic.# C10-762093
>707-459-0474
>
>
>On Jun 19, 2013, at 3:26 PM, Drake wrote:
>
>>That was my first call. They said use a full size neutral. I'm not 
>>satisfied with that answer. The combined experience and knowledge 
>>on this list far exceeds that of any tech support person.
>>
>>At 04:27 PM 6/19/2013, you wrote:
>>>Drake,
>>>Why not discuss this with Power One tech support?
>>>Allan
>>>
>>>Allan Sindelar
>>><mailto:Allan at positiveenergysolar.com>Allan at positiveenergysolar.com
>>>NABCEP Certified PV Installation Professional
>>>NABCEP Certified Technical Sales Professional
>>>New Mexico EE98J Journeyman Electrician
>>>Founder and Chief Technology Officer
>>>Positive Energy, Inc., a Certified B CorporationTM
>>>3209 Richards Lane
>>>Santa Fe, New Mexico 87507
>>>505 424-1112 office 780-2738 cell
>>><http://www.positiveenergysolar.com/>www.positiveenergysolar.com
>>>
>>>On 6/19/2013 1:55 PM, Drake wrote:
>>>>A very common cable for 100 A service conductors has 2 - #2 AL 
>>>>wires and 1 - #4 AL for the neutral;  200 A will have 2 - 4/0 AL 
>>>>wires and 1 - 2/0 for the neutral.   If I run # 2 to limit the VD 
>>>>on the run to the panel and reduce the neutral to #4, #12 copper 
>>>>phase and neutral will still connect to the inverters.  This 
>>>>would be code for a feeder to a separate structure.
>>>>
>>>>Does the Power One inverter actually have a major imbalance 
>>>>resulting in substantial neutral currents? If so, it is really a 
>>>>120 V inverter for VD calculations.
>>>>
>>>>
>>>>  03:37 PM 6/19/2013, you wrote:
>>>>>Content-Type: multipart/related;
>>>>>         boundary="----=_NextPart_000_00A6_01CE6CE9.D20EFB20"
>>>>>Content-Language: en-us
>>>>>
>>>>>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
>>>>><mailto:john at renewableassociates.com>john at renewableassociates.com
>>>>>www.renewableassociates.com
>>>>><2221ada.jpg>
>>>>>
>>>>>
>>>>>
>>>>>From: 
>>>>><mailto:re-wrenches-bounces at lists.re-wrenches.org>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: 
>>>>><mailto:re-wrenches at lists.re-wrenches.org>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/>http://athens-electric.com/
>>>>>
>>>>>
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