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<p>I wasn't clear or accurate in my comment " a lot more surface
area in 8" pipe 5-6 feet into the earth" which we have never
done. should have said "....5-6 feet into 1.5 yards of concrete
embedded in the ground" Having seen many instances of steel in
concrete from demo jobs, little or no rust is found where steel is
encased in concrete, at least in these parts of the northern
Sierra.</p>
<p> That 2 sq ft X 1/4" thick bare steel plate or other
accepted electrodes "shall be embedded below permanent moisture
level" (that's pretty fuzzy) has been in the code for a long time,
it must be there because it works.<br>
</p>
<p>Bill</p>
<pre class="moz-signature" cols="72">Feather River Solar Electric
Bill Battagin, Owner
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849
CA Lic 874049
<a class="moz-txt-link-abbreviated" href="http://www.frenergy.net">www.frenergy.net</a></pre>
<div class="moz-cite-prefix">On 6/25/2021 9:16 AM, Ray wrote:<br>
</div>
<blockquote type="cite"
cite="mid:2ed9b18e-b13b-0e82-30ba-9c0c52843242@solarray.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<p>Copper can get a pretty good oxide layer on it as well, but I'm
not versed in the science enough to know how any of that effects
the conductivity. Instead, I assume that the NEC has
investigated corrosion, and so we just follow the code. For
plate electrodes (250.52(A)(7)), it just specifies dimensions
and thickness, and specifically mentions bare iron or steel.
250.52(A)(3)(<i>1</i>) for Concrete encased electrodes (UFER)
also allows bare steel reinforcing rod, while section (<i>2</i>)
allows your #4 copper UFER. <br>
</p>
<p>Lacking further information, I just go with the code, and my
own ground impedance measurements over the years. My small
sampling of measurements has found steel rebar grounds and large
steel pipe (4"D and larger) to be under 25 ohms, while I have
measured copper coated rods as high as 700 ohms in dry soil. I
haven't measure copper UFER or compared it to steel, so again, I
don't know. It might be better than steel, but all are allowed
by code. <br>
</p>
<p>Ultimately it might come down to soil and weather conditions
for different areas?<br>
</p>
<pre class="moz-signature" cols="72">Ray Walters
Remote Solar
303 505-8760</pre>
<div class="moz-cite-prefix">On 6/25/21 10:35 AM, Dana Orzel
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:001f01d769cf$54e130f0$fea392d0$@solarwork.com">
<pre class="moz-quote-pre" wrap="">That\u2019s why we use the Ufer, our AHJ assumes that once a layer of rust develops this is not valid...........
Dana Orzel Great Solar Works, Inc.
C - 208.721.7003 <a class="moz-txt-link-abbreviated" href="mailto:dana@solarwork.com" moz-do-not-send="true">dana@solarwork.com</a>
Idaho Contractor - # 028765 Idaho PV # 028374
NABCEP # 051112-136 <a class="moz-txt-link-abbreviated" href="http://www.greatsolarworks.com" moz-do-not-send="true">www.greatsolarworks.com</a>
"Responsible Technologies for Responsible People since 1988"
\uf050 Please consider the environment before printing this email.
-----Original Message-----
From: RE-wrenches <a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches-bounces@lists.re-wrenches.org" moz-do-not-send="true"><re-wrenches-bounces@lists.re-wrenches.org></a> On Behalf Of Ray
Sent: Thursday, June 24, 2021 4:51 PM
To: <a class="moz-txt-link-abbreviated" href="mailto:re-wrenches@lists.re-wrenches.org" moz-do-not-send="true">re-wrenches@lists.re-wrenches.org</a>
Subject: Re: [RE-wrenches] Grounding Top of Pole Mount Array with a Ufer
We always put our assumption in our plan notes, based on our interpretation of 250.52(A)(7). AHJs have never questioned it, and we also tie the pole to any rebar, so its all one big happy grounding electrode.
Ray Walters
Remote Solar
303 505-8760
On 6/24/21 6:49 PM, frenergy wrote:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Ray,
I couldn't agree more, its been my experience over the
years that using 20 feet of #4 rebar in a building's footing was
kosher and accepted NEC 250.52(3). There's a heck of a lot more
surface area in 8" pipe 5-6 feet into the earth than rebar in a
foundation footing. The ground at the bottom of the pole footing is
also more likely to be damper. Our AHJ has always accepted the steel
pole as a ground rod....common sense prevails sometimes.
Bill
Feather River Solar Electric
Bill Battagin, Owner
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849
CA Lic 874049
<a class="moz-txt-link-abbreviated" href="http://www.frenergy.net" moz-do-not-send="true">www.frenergy.net</a>
On 6/24/2021 7:31 AM, Ray wrote:
</pre>
<blockquote type="cite">
<pre class="moz-signature" cols="72">Usually a steel pole in concrete has enough surface area to qualify
as a plate electrode under 250.52(A)(7). It needs to be at least 2
sq ft and 1/4" thick, and have an electrically conductive surface. So
we just drill and tap our ground connection into the pole, near the
combiner box.
Ray Walters
Remote Solar
303 505-8760
</pre>
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