[RE-wrenches] box fill calcs
R. Walters
walters at taosnet.com
Thu Nov 20 08:54:34 PST 2008
I thought you measured the cubic inches of any extra stuff like that,
and calculated that for the total cu in. fill in the box.
Personally, I never size boxes that close. I'm a real baby, I like
lots of extra room when wrestling those bigger cables.
Ray
On Nov 20, 2008, at 8:40 AM, Jeff Blick 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
>
> -----Original Message-----
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> Subject: RE-wrenches Digest, Vol 1, Issue 336
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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
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> List sponsored by Home Power magazine
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>>
>>
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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
>
> Voice: 413-259-3750
> Fax: 413-825-0703
> 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>
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>
> 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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R. Walters
Solarray.com
NABCEP # 04170442
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