Backfeeding a "240V Delta with a stinger" [RE-wrenches]

[Mark Frye]

Peter,

Please do let us know what you find out.

MPF

P.S. I believe the term "stinger" is more indicative of the 480V delta 
where the high leg is running at 277V. Note code requirement to identify 
with orange, such requirement not applied to the 240 delta high leg.


Peter Parrish wrote:
> 
> We have two customers with 240V/3P service with one center tap (neutral 
> and
> grounded). I understand how these work in a conventional (i.e. non-PV)
> world. Assume for the purposes of discussion the center tap is between 
> legs
> L1 and L2. The following voltages can be derived: 
> 
> L1-N 120V, 
> L2-N 120V, 
> L1-L2=L2-L3=L3-L1 240V, 
> L3-N 208V
> 
> My question is, "With the latest NEC requirement of wiring grid-tied
> inverters with a connection to neutral, how can we backfeed the L2-L3 or
> L1-L3 legs? Are confined to the L1-L2 connection?"
> 
> I have been told that Fronius might have a workaround by resetting a 
> jumper
> (I'll look into this) but the question still remains.
> 
> Since we have two customers with this situation, and one job we have 
> already
> started, any help would be greatly appreciated.
> 
> - Peter
> 
> Peter T. Parrish, Ph.D., President
> California Solar Engineering, Inc.
> 820 Cynthia Ave., Los Angeles, CA 90065
> Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
> CA Lic. 854779, NABCEP Cert. 031806-26
> peter.parrish at calsolareng.com 
> 
> -----Original Message-----
> From: Bob Ellison [mailto:reellison at gmail.com] 
> Sent: Monday, November 12, 2007 7:24 PM
> To: RE-wrenches at topica.com
> Subject: [Norton AntiSpam] Re: Heating oil vs. electric heat 
> [RE-wrenches]
> 
> 
> 
> Electric is more expensive, hands down. In this area, (Northern New 
> York)
> electric is pushing .18 (18 cents per KWH) generally you have to double 
> the
> figures on the energy tags in the stores to get close to the true 
> operating
> cost of appliances.
> 
> Bob Ellison
> 
> 
> On 11/12/07, Joel Davidson <joel.davidson at sbcglobal.net> wrote:
> >
> >
> > Would a wrench in heating oil territory please tell me if it is cheaper 
> > to
> > heat with oil than electricity?
> >
> > I was told:
> > 138,000 btu per gallon of fuel oil at $3.00 per gallon.
> > 3,413 btu per kWh of electricity at $0.11 per kWh.
> > Efficiency of oil = 78%
> > Efficiency of electric furnace = 95%.
> > Cost per 1,000,000 btu from oil = $27.73.
> > Cost of 1,000,000 btu from electric furnace = $33.94.
> >
> > Thanks in advance,
> > Joel Davidson
> >
> >
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> 
> [Non-text portions of this message have been removed]
> 
> 
> - - - -
> Hosted by Home Power magazine
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> 



Berkeley Solar Electric Systems


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