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<p>I also don't understand requiring 100 amps for an auxillary
dwelling. 230.79 requires a minimum service of 100 amps for a
single family dwelling, but that is a service requirement, not a
requirement for a feeder to another building. Even 230.79(D) says
all other buildings only require a 60 amp service. I think we'd
all like to know where the AHJ is getting these requirements. Is
it local amendments that were added, or is it just a possible
misinterpretation? <br>
</p>
<p>I suggest possibly reviewing with the AHJ the article 100
definitions of Service (connection to the Utility) and Feeder.
Article 230 covers Services and does Not apply to feeders. The
ADU would only need 100 amps if it had its own service meter. <br>
</p>
<pre class="moz-signature" cols="72">Ray Walters
Remote Solar
303 505-8760</pre>
<div class="moz-cite-prefix">On 4/21/20 10:05 AM,
<a class="moz-txt-link-abbreviated" href="mailto:drake.chamberlin@redwoodalliance.org">drake.chamberlin@redwoodalliance.org</a> wrote:<br>
</div>
<blockquote type="cite"
cite="mid:82eaf8d64c0100768364cb22282b438e@redwoodalliance.org">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<p>The voltage drop recommendations in the code are actually not
requirements, but recommendations. Some locations make them
requirements, but if the AHJ is following the NEC without
amendment, the 2% and 3% recommended drops are only
recommendations. </p>
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monospace"> </div>
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<p><br>
</p>
<p id="reply-intro">On 2020-04-20 10:56, Mac Lewis wrote:</p>
<blockquote type="cite" style="padding: 0 0.4em; border-left:
#1010ff 2px solid; margin: 0">
<div id="replybody1">
<div dir="ltr">This is an example of where some code
requirements bump up against logic. I believe the AC
voltage will be quite usable at the site, just not for code
requirements of the AHJ, and it may get pretty low during
high usage times. They make the electrician size it for
100A minimum for an ADU, even though the loads are pretty
minimal, and then require <5% VD from the main service
entrance. That is the requirement for the certificate of
occupancy.
<div> </div>
<div> Luckily, off-grid buildings don't have these
requirements at all. I'm going to size it as an off-grid
and probably tie it in at some point in the future.</div>
<div> </div>
<div>Thanks for the input.</div>
</div>
<br>
<div class="v1gmail_quote">
<div class="v1gmail_attr" dir="ltr">On Sun, Apr 19, 2020 at
10:20 AM <<a
href="mailto:drake.chamberlin@redwoodalliance.org"
rel="noreferrer" moz-do-not-send="true">drake.chamberlin@redwoodalliance.org</a>>
wrote:</div>
<blockquote class="v1gmail_quote" style="margin: 0px 0px 0px
0.8ex; border-left: 1px solid #cccccc; padding-left: 1ex;">
<div style="font-size: 10pt; font-family:
Verdana,Geneva,sans-serif;">
<p>We had a similar situation, and are now feeding a
battery bank with a pair of 48 V Iota chargers. Iota
can run on very low voltages. We have one Iota on each
leg of the the 120/240 split phase to balance the
load. It works.</p>
<div
id="v1gmail-m_8568014601580466354gmail-m_-6662448293164808202signature">---<br>
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monospace;"> </div>
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<p><br>
</p>
<p
id="v1gmail-m_8568014601580466354gmail-m_-6662448293164808202reply-intro">On
2020-04-18 21:25, Ray wrote:</p>
<blockquote style="padding: 0px 0.4em; border-left: 2px
solid #1010ff; margin: 0px;">
<div
id="v1gmail-m_8568014601580466354gmail-m_-6662448293164808202replybody1">
<div>
<p>When doing the volt drop calculation, be sure
to correct for temperature, per the note after
table 8, chapter 9 of the NEC. The table values
default at 167 deg F (75 C). An underground
cable will be operating closer to earth
temperature. When I run volt drop for a 4/0
copper cable at 60 deg F, I'm seeing that you
could go over 60 amps and maintain a volt drop
of 3%. </p>
<p>Not sure what the requirements for the building
are, but that exceeds most of my off grid
systems. 60+ amps at a final voltage of 232 v
is almost 14kW. Is there air conditioning? What
are the calculated loads for this building? Is
the inspector actually calling this a problem? </p>
<p>I would do a proof of concept: turn every light
on in the place, along with some typical
appliances (hair dryer, microwave) hit a
circular saw to really make the point, with a
DMM plugged in. I found long ago that actual
measured volt drop was not as bad as Chapter 9
first predicts.</p>
<p><br>
</p>
<pre>Ray Walters
Remote Solar
303 505-8760</pre>
<div>On 4/18/20 3:41 PM, Darryl Thayer wrote:</div>
<blockquote style="padding: 0px 0.4em;
border-left: 2px solid #1010ff; margin: 0px;">
<div dir="ltr">
<div style="font-family: 'times new
roman',serif; font-size: large;">Hi Mac,
There are a few questions like is it Al or
Cu wire, What makes it unusable? </div>
<div style="font-family: 'times new
roman',serif; font-size: large;">for Voltage
drop, I use Vd=2KIL/CMA for your case the
unknown is the current. The installation of
an inverter with grid support. Many
inverters have this, you want a multimode
inverter such as a Schneider, Outback,
SolArk and I could name at least 4 more. A
normal house will run on 30 amps. So assume
30 amps, Vd=2x21.6x30x1100/211600 =6.7 volts</div>
<div style="font-family: 'times new
roman',serif; font-size: large;">So if the
main house is at 240 Volts the remote house
is at 233 Volts. The multimode inverter
could be set at grid support beyond 30
Amps. For higher house loads the inverter
can support up to 30 to 50 amps additional.
(SolArk is 50 amp) I would add a balancing
transformer at the end of the line to make
the 120 loads balance. (an Autotransformer)
such that 120 volts loads are balanced and
the load is shared between 240-Volt
conductors. Based on my customers'
experiences I would use AGM LA batteries, as
I expect low usage of the battery and quick
recharge, but that is the customer's
choice. I had one customer that had 10
years on the float-AGM battery set. </div>
</div>
<br>
<div>
<div dir="ltr">On Fri, Apr 17, 2020 at 8:15 AM
Mac Lewis <<a
href="mailto:maclewis1@gmail.com"
rel="noreferrer" moz-do-not-send="true">maclewis1@gmail.com</a>>
wrote:</div>
<blockquote style="margin: 0px 0px 0px 0.8ex;
border-left: 1px solid #cccccc;
padding-left: 1ex;">
<div dir="ltr">Hi wrenches,
<div> </div>
<div>I've got a architect client with a
sub-optimal power situation on one of
the projects he is working on. I'm
running through a couple of scenarios
that may work. Its a ADU (accessory
dwelling unit) that is about 1100' from
power. The farmer had taken it upon
himself to bury some 4/0 a few years ago
to run power out there. Voltage drop is
the big issue and its not going to pass
the AHJ inspection. We could just ditch
the grid and go off-grid, but it seems
like a shame to not tap into the grid
resource. Instead of dealing with the
voltage drop, I was thinking it may make
sense to rectify that low AC voltage
input and parallel a smallish battery
bank (size is yet to be determined),
then use an off-grid inverter to serve
the loads at good voltage.</div>
<div> </div>
<div>I am looking for feedback on this
concept. What do you think?</div>
<div> </div>
<div>Also, are there any recommendations
for good quality rectifiers with wide
input voltage window? </div>
<div> </div>
<div>Thanks in advance for your help</div>
<div>
<div> </div>
-- <br>
<div dir="ltr">
<div> </div>
<div><span style="color: #305a78;
font-family: 'times new
roman',serif;"> </span></div>
<div> </div>
Mac Lewis<br>
<br>
<p align="left"><span style="color:
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Verdana,Arial,Helvetica,sans-serif;"><span
style="font-size: small;"><span
style="font-family: arial;
font-weight: normal; color:
#305a78;"><span
style="font-family: 'times
new roman',serif;">"Yo solo
sé que no sé nada." </span><span
style="font-weight: bold;
color: #686868;"><span
style="font-family: 'times
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