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

Thu Jun 20 13:35:17 PDT 2013

Unfortunately, the benefits are somewhat limited since you still have to 
size the neutral at the same size as your EGC, and you have to upsize 
your EGC thanks to your voltage drop. So now instead of a #6 neutral, 
you're running them as 8s? Hey, every bit helps...

On 2013/6/20 16:18, Drake wrote:
> 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
>> future at pacific.net <mailto: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*
>>>> _Allan at positiveenergysolar.com <mailto: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 Corporation^TM
>>>> 3209 Richards Lane
>>>> Santa Fe, New Mexico 87507
>>>> *505 424-1112 office 780-2738 cell*
>>>> _www.positiveenergysolar.com <http://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
>>>>>> john at renewableassociates.com <mailto:john at renewableassociates.com>
>>>>>> www.renewableassociates.com <http://www.renewableassociates.com/>
>>>>>> <2221ada.jpg>
>>>>>>
>>>>>>
>>>>>>
>>>>>> *From:* re-wrenches-bounces at lists.re-wrenches.org
>>>>>> <mailto: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
>>>>>> <mailto: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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>>>>>
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