[RE-wrenches] box fill calcs

Thu Nov 20 08:14:35 PST 2008

Jeff-

I have always interpreted the code to include a "connector" for each set of
wires. I'm tyring to remember what a past coworker said about it and I
thought there was something that referenced types of connectors in a box. If
I find it I'll write again.

Jason

On Thu, Nov 20, 2008 at 8:40 AM, Jeff Blick <jeff.blick at sunlightsolar.com>wrote:

>
> Hi wrenches,
> In Reading 314.16(B)there is no mention of including polaris lugs or the
> like in box fill calcs.  Do any of you include such equipment in your box
> fill calcs?  If so how do you account for them (ie count it as two
> conductors based on the size of the conductors that are landing in it)
> Thanks wrenches!
>
>
> Jeff Blick
> PV installer
> Sunlight Solar Inc.
> 4 NW Franklin
> Bend, OR 97701
> direct: 541-306-4196
> fax: 541-322-1911
> jeff.blick at sunlightsolar.com
> www.sunlightsolar.com
>
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> Today's Topics:
>
>   1. Re: grid-tie inverters & generators
>      (Jeff Clearwater, Village Power Design)
>   2. Re: utility EDS signage (Kent Osterberg)
>   3. Re: inverters/ generators and noise (robert ellison)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 20 Nov 2008 00:42:29 -0500
> From: "Jeff Clearwater, Village Power Design" <jeffc at villagepower.com>
> Subject: Re: [RE-wrenches] grid-tie inverters & generators
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Message-ID: <p06240806c54aa84bd6a8@[192.168.2.7]>
> Content-Type: text/plain; charset="us-ascii"; Format="flowed"
>
> Hi Folks,
>
> We burnt up a gen set's voltage regulator on an off-grid system sunny
> island/sunny boy system when we took the sunny island's off-line but
> didn't shut off the sunny boy.  So the SB backfed the genny and fried
> the very expensive voltage regulator on a 30 KW system.  SMA had us
> install a relay to tell the SB to shut down as soon as the AC
> reference from the SI was gone.  Same situation as grid-tie really in
> terms of your question.
>
> Jeff
>
>
>
> >Hi Kelly
> >
> >It is an interesting issue and was just dicussing this the other day.
> >
> >I think what happens if the inverter backfeeds the genny, the
> >generator voltage will go up, if it goes up enough, it will go
> >outside the window of the inverter and the inverter will drop out,
> >voltage will them return to normal, inverter will reconnect and
> >repeat.
> >
> >But I sure wouldn't want to fix the generator.  A relay powered from
> >the grid will take care of the problem.
> >
> >jay
> >
> >peltz power
> >On Nov 19, 2008, at 5:24 PM, Kelly Keilwitz, Whidbey Sun & Wind wrote:
> >
> >>Wrenches,
> >>I'm dredging up this subject again (previous postings 6/08) with a
> >>simple question that doesn't seem to have been answered:
> >>
> >>Is there any issue connecting a batteryless grid-tie PV system to
> >>the load side of a panel that is backed-up by a generator on an
> >>automatic transfer switch, when the grid is down and the generator
> >>running?
> >>
> >>In this case the PV is 5.7kW, the inverter an SMA 6000, the
> >>generator unknown size/type, but propane, automatic start, and
> >>backing up the entire main panel.
> >>
> >>SMA tech support first said it's OK, then that the generator will
> >>blow up. I can imagine, if the inverter tries to sync with the
> >>inverter, that the voltage could rise, causing the inverter to
> >>disconnect, wait 5 minutes, repeat. Is there anything nasty that
> >>could happen?
> >>
> >>Thanks,
> >>-Kelly
> >>
> >>
> >>Kelly Keilwitz, P.E.
> >>Whidbey Sun & Wind, LLC
> >>Renewable Energy Systems
> >>NABCEP Certified PV Installer
> >>987 Wanamaker Rd,
> >>Coupeville, WA 98239
> >>PH & FAX 360-678-7131
> >><>sunwind at whidbeysunwind.com
> >>
> >>
> >>
> >>
> >>
> >>_______________________________________________
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> --
> ~~~~~~~~~~~~~
> Jeff Clearwater
> Senior Design Engineer
> NABCEP (tm) Certified Solar PV Installer
> http://www.nabcep.org/
> Village Power Design/NorthEast Solar Design
> Turnkey Solar Design & Installation for the Commercial Sector
> http://www.villagepower.com
> gosolar at villagepower.com
>
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> 65 Schoolhouse Rd
> Amherst, MA 01002
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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> ------------------------------
>
> Message: 2
> Date: Wed, 19 Nov 2008 23:24:59 -0800
> From: Kent Osterberg <kent at coveoregon.com>
> Subject: Re: [RE-wrenches] utility EDS signage
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Message-ID: <492510CB.1020708 at coveoregon.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Phil,
>
> NEC 690.17 says "Where all terminals of the disconnecting means may be
> energized..."  It would take a pretty rare malfunction of a grid
> connected inverter to energize the load terminals of the utility
> disconnect.  But we have some AHJs that require this label on every ac
> disconnect, all the way back to the utility meter, anyway.  The warning
> is appropriate on the dc disconnect of almost all inverters because the
> capacitors in the inverter take a few minutes to bleed off.
>
> To me, the bigger hassle are plaques required by 705.10.  Can anyone
> give me a reasonable explanation for their value in a utility
> interactive system? I can understand if there is a grid backup system -
> emergency personnel may need to know where to turn off the backup power;
> but a grid interactive inverter shuts down when there service is shut
> down.  It seems to me that this plaque is likely to send an emergency
> responder on a wild goose chase.
>
> Kent Osterberg
> Blue Mountain Solar
>
> Phil Schneider wrote:
> > Wrenches,
> >
> > Our utilities require an external AC disconnect between the inverter and
> the
> > point of interconnection, located next to the meter.  In the past, we
> have
> > marked this switch with the language in 690.17 (although no AHJ or
> utility
> > has required it).  Because we generally argue against the necessity of
> this
> > switch, I don't feel it is accurate to say that "terminals on both the
> line
> > AND load sides may be energized in the open position".
> >
> > Do other Wrenches post this plaque?  Is there a way that both line AND
> load
> > terminals of this switch could be energized?  (other than an inverter not
> > paying attention to its UL listing?)
> >
> > Thanks again for your thoughts,
> > P.
> >
> > Phil Schneider
> > Creative Energies
> >
> >
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>
> ------------------------------
>
> Message: 3
> Date: Thu, 20 Nov 2008 06:38:45 -0500
> From: "robert ellison" <reellison at gmail.com>
> Subject: Re: [RE-wrenches] inverters/ generators and noise
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Message-ID:
>        <dae2914c0811200338t53f57516k77425841b255597 at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Probably due to the load of the charger, try changing the rpm a little
> (higher) if you can. Might help. I have had stoves that wouldn't light
> under
> full charger load. They did better at a somewhat higher rmp (frequency)
>
> Bob
>
> On Thu, Nov 20, 2008 at 12:12 AM, jay peltz <jay at asis.com> wrote:
>
> > Hi All,
> >
> > here is along those same lines a question about line noise.
> >
> >
> > System 15kw diesel generator
> >
> > 4 stack outback at 24v   120v/240vac
> >
> > 3000 amp hr industrial batteries.
> >
> > when genny running, 59.5-60 hz
> > voltage 122/244
> >
> >
> > Symptoms.
> >
> > when charging there is some buzzing on some electrical equipment in the
> > house.  Stove pizeo won't lite, transformer on furnace runs hot, Fridge
> > makes more noise.
> > Seems to get worse at end of charge cycle.
> >
> >
> > Now, with inverter only,  no noise, humm, buzz etc.
> >
> > With Genny only no buzz, humm, etc.
> >
> >
> > Any advice?
> >
> > thanks,
> >
> > jay
> >
> > peltz power
> >
> >
> >
> >
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-- 
Jason Lombard CSBA
Open Hand Solar LLC.
Pecos, NM. 87552
505 795 8646
openhandsolar at gmail.com
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