[RE-wrenches] Supply Side Interconnections - Maximum Backfeed

[Michael Kelly]

Kirpal,

That was always my interpretation as well.  So in the case of a 400A
service, I can backfeed 400A when utilizing a supply side connection.
Others have thoughts on this?

- Mike
--
Michael Kelly
Project Manager / Project Engineer
NABCEP Certified Solar PV Installer ™

SolarFlair Energy, Inc.
11 Mayhew Street
Framingham, MA 01702
Direct Mobile: 617-899-9840
Main Phone: 508-293-4293
Main Fax: 508-293-4003
mike at solarflair.com


On Thu, Mar 4, 2010 at 4:16 PM, Kirpal Khalsa <solarworks at gmail.com> wrote:

> Mike.....i may be wrong....but I think i am right....you are limited by the
> wire size feeding the supply and/or  the transformer size which supplies the
> service.....depending on the physical location of the tap you may be limited
> by the enclosure and the enclosure ratings as well
> would love to hear any other ideas...
> Cheers,
> --
> Sunny Regards,
> Kirpal Khalsa
>
> NABCEP Certified Solar PV Installer
> Renewable Energy Systems
> www.oregonsolarworks.com
> 541-218-0201 m
> 541-592-3958 o
>
>
>   On Thu, Mar 4, 2010 at 12:50 PM, Michael Kelly <mike at solarflair.com>wrote:
>
>>   Hi All,
>>
>> Next to grounding, I find the calculation of the maximum amount of
>> backfeed current allowed in a supply side connection to be the most vague
>> issue in Article 690.  Let's assume we have a 400A, 480/277 service in a
>> commercial building, a 400A main service disconnect, and the jurisdiction is
>> under NEC 2008.  What is the maximum backfeed current allowed in a supply
>> side connection?  The only place the code points you to is 230.82(6), which
>> is no help, or to Article 705, which is no help either.  I know that in the
>> draft version of NEC 2011, there is an expansion of 705.12(A) which states "
>> * *Supply Side. An electric power production source shall be permitted to
>> be connected to the supply side of the service disconnecting means as
>> permitted in 230.82(6). The sum of the ratings of all overcurrent devices
>> connected to power production sources shall not exceed the rating of the
>> service."  That is a helpful sentence from the Code, but as it is in draft
>> form, what do we do under NEC 2008?  What have you used as a maximum
>> backfeed current for supply side connections?
>>
>> Thanks,
>> Mike
>> --
>> Michael Kelly
>> Project Manager / Project Engineer
>> NABCEP Certified Solar PV Installer ™
>>
>> SolarFlair Energy, Inc.
>> 11 Mayhew Street
>> Framingham, MA 01702
>> Direct Mobile: 617-899-9840
>> Main Phone: 508-293-4293
>> Main Fax: 508-293-4003
>> mike at solarflair.com
>>
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