[RE-wrenches] Grounding Top of Pole Mount Array with a Ufer

[frenergy]

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                       dana at 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-bounces at lists.re-wrenches.org> On 
>> Behalf Of palumbo131m at gmail.com
>> Sent: Wednesday, June 23, 2021 9:33 PM
>> To: RE-wrenches <re-wrenches at 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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