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.
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.
Bill
Feather River Solar Electric
Bill Battagin, Owner
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849
CA Lic 874049
www.frenergy.net
On 6/25/2021 9:16 AM, Ray wrote:
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)(/1/) for
Concrete encased electrodes (UFER) also allows bare steel reinforcing
rod, while section (/2/) allows your #4 copper UFER.
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.
Ultimately it might come down to soil and weather conditions for
different areas?
Ray Walters
Remote Solar
303 505-8760
On 6/25/21 10:35 AM, Dana Orzel wrote:
That’s 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 - 208.721.7003d...@solarwork.com
Idaho Contractor - # 028765 Idaho PV # 028374
NABCEP # 051112-136www.greatsolarworks.com
"Responsible Technologies for Responsible People since 1988"
Please consider the environment before printing this email.
-----Original Message-----
From: RE-wrenches<re-wrenches-boun...@lists.re-wrenches.org> On Behalf Of Ray
Sent: Thursday, June 24, 2021 4:51 PM
To:re-wrenches@lists.re-wrenches.org
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:
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
www.frenergy.net
On 6/24/2021 7:31 AM, Ray wrote:
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
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