480/277 Backfeed [RE-wrenches]

[Jeff Clearwater]

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Hi Matt,

Thanks!  It wasn't that post but another local wrench here that ran 
into not being able to backfeed a 1200 AMP 480 GFCI breaker due to it 
not being backfeed rated.  They found a substitute that was rated I 
do believe.

We are at 800 Amps so hopefully we are good to go.  My electrician 
should be getting back to me on it.

Thanks!

Jeff C.



>All,
>
>Jeff C asked about GFCI 480 Service requirements.
>
>It is not "480" specifically... And it is not "all"... Here's the NEC lingo:
>
>230.95 Ground-Fault Protection of Equipment
>Ground-fault protection of equipment shall be provided for solidly grounded
>wye electrical services of more than 150 volts to ground but not exceeding
>600 volts phase-to-phase for each service disconnect rated 1000 amperes or
>more. The grounded conductor for the solidly grounded wye system shall be
>connected directly to ground without inserting any resistor or impedance
>device.
>The rating of the service disconnect shall be considered to be the rating of
>the largest fuse that can be installed or the highest continuous current
>trip setting for which the actual overcurrent device installed in a circuit
>breaker is rated or can be adjusted.  <End of NEC reference>
>
>The nutshell version is that 277/480 service disconnects rated 1000 Amps or
>more need to have ground-fault protection.
>
>What may be in Jeff's mind is a post from a month or so ago related to
>service requirments in a Flood Zone and the local AHJ saying that the whole
>thing would have to be GFCI protected if below the Base Flood Elevation.  It
>turns out that the AHJ's initial interpretation was subsequently revised...
>Go figure!  The new, and more appropriate IMHO, interpretation was that a
>service cannot be located at an elevation less than 1 foot above Base Flood
>Elevation (100 Year Flood Height), regardless of GFCI...  Services located
>in these Flood Zones need to be elevated.  Permanent service platforms &
>stairways need to be provided.  Loads connected to the elevated service are
>allowed to be located below the BFE+1 height as long as they are GFCI
>protected.
>
>For those who care... The case that originally put this issue on my radar
>came out as follows:  We paid a licensed surveyor $850 to determine and
>certify the BFE for the area of the parcel which was affected by our work.
>The county charged an additional $288 to look at the form (standard 4 page
>FEMA form).  The outcome of the survey was that, as long as all serviceable
>equipment was located 3' above grade or higher, no additional mitigation was
>required.  Since there were no walls or stem-wall footing/foundations
>related to the trellis-structure and it was deemed "non-dwelling", the
>County backed off their requirement that "in-progress" and
>"post-construction" certifications be provided by the surveyor.  This saved
>us $650 in potential additional fees.
>
>The system is installed and signed off by the County.  Awaiting Utility
>inspection and net-meter set.
>
>Hope this helps,
>
>Matt Lafferty
>mlafferty at universalenergies.com
>
>
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-- 
~~~~~~~~~~~~~
Jeff Clearwater
Village Power Design
Sustainable Energy & Water Solutions for Home & Village
http://www.villagepower.com
gosolar at villagepower.com
NABCEP (tm) Certified Solar PV Installer

530-470-9166
877-SOLARVillage
877-765-2784
65 Schoolhouse Rd
Amherst, MA 01002
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