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
On 6/24/21 8:16 AM, Dana Orzel wrote:
For all of our free standing arrays we now use a Ufer clamp to the
rebar either cage or just anti spin rebar that is welded to the pole
in the concrete, with #4 braided copper up to the pole combiner box,
inverter, etc. for our ground.
With a pole mount & a concrete base it is way easier & less expensive
than a ground rod, & the inspector seems happier with this approach.
Dana Orzel Great Solar Works, Inc.
C - 208.721.7003 d...@solarwork.com
Idaho Contractor - # 028765 Idaho PV # 028374
NABCEP # 051112-136 www.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 palumbo1...@gmail.com
Sent: Wednesday, June 23, 2021 9:33 PM
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Subject: Re: [RE-wrenches] Top of Pole Mount Array on Ledge
Ben,
There is a way if the ledge is solid and true. Twice I have done the
following with ledge at 18” to 24” below grade. Excavate down to
ledge, drill down into the ledge and you will determine the
suitability of the following method. Drill for a pattern of many
rebar penetrations in to the ledge. Drill to a reasonable depth (as
deep into the ledge as you are able) in my case it was based on our
drilling tool and bit length capabilities. We used a large sono tube.
42” as a recall, both of these jobs were over 12 years ago and my
recall on the exact size may be off.
Determine the best adhesive product to use in your drilled holes for
the rebar, again my memory fails as to what we used based on
recommendation from a local civil engineer. The sono tube height
above grade was determined to be 2’ for one TPM12 and 3.5’ above
grade for a TPM16. Depth down to the ledge determines how high above
grade you need the concrete footing/base. Use rebar lengths that will
end a few inches below the finished surface. For grounding you can
coil up ground wire and lay it on the surface of the ledge before
your concrete pour. I ran the ground wire through a short length of
1/2” or 3/4” PVC conduit, to protect the copper ground wire where it
comes out of the concrete. Place the conduit coming out of the
concrete with the ground wire just to the side of where the mounting
plate base for the TPM will be and fill the PVC conduit with a good
caulk sealer to keep air and water out of this hole as a nexus of
concrete, and air will corrode the copper. The TPM’s for those two
jobs were made of 8” SCHD 80 steel, we had a large plate welded to
the bottom with 4 vertical side supports on the pipe up about a foot.
Place the appropriate sized anchor bolts in the concrete pour to
match your TPM base. Both of these TPM’s have worked out well over
the years. Local conditions will determine the suitability of this
method.
Sent from my iPhone
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