Pretty difficult to move it once entombed in concrete....
73
Jim W7RY
--------------------------------------------------
From: "K8RI on TT" <k8ri-on-towertalk@tm.net>
Sent: Sunday, April 17, 2011 7:31 PM
To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] grounding quesitons: Ufer, strap, exothermic welds
> On 4/17/2011 10:16 PM, Jim W7RY wrote:
>> Oh! And I see Hargar makes a rebar clamp!
>>
>> http://www.harger.com/products/idx.cfm?subc4id=256&p=1&oiid=824&thid=690&footid=0&footinfoid=0
>>
>
> They'd probably work well in concrete, but I've never seen one of these
> hold up for more than two years "at most" in our soil.
>
> Typically you can really reef on them so they are plenty tight and in a
> year you can move them with your fingers.
>
> 73
>
> Roger (K8RI)
>
>> 73
>> Jim W7RY
>>
>>
>> --------------------------------------------------
>> From: "Jim W7RY"<w7ry@inbox.com>
>> Sent: Sunday, April 17, 2011 7:07 PM
>> To: "Mat Eshpeter"<kk1c@live.com>;<towertalk@contesting.com>
>> Subject: Re: [TowerTalk] grounding quesitons: Ufer, strap, exothermic
>> welds
>>
>>> The problem is that strap can decay and degrade over time directly in
>>> some
>>> types of earth AND As you have pointed out, connection to strap is
>>> problematic at best unless it is also welded (brazed using silver
>>> bearing
>>> welding) The only place I recommend strap is between the external
>>> grounding electrode system and the building coax entrance panel. Harger
>>> http://www.harger.com/ makes a special welded system to transition the
>>> strap to a copper bar and then it's cad welded to the #2AWG bare tinned
>>> grounding system.
>>>
>>> Most communications sites (cellular and public safety) use #2 AWG tinned
>>> underground conductors that are exothermically welded together. Some
>>> Federal Government installations may have specifications that require
>>> larger wire. But over the years, solid tined wire has proven to be the
>>> best.
>>>
>>>
>>> 73
>>> Jim W7RY
>>> Motorola Solutions
>>>
>>>
>>>
>>>
>>>
>>> From: Mat Eshpeter
>>> Sent: Sunday, April 17, 2011 9:34 AM
>>> To: w7ry@inbox.com ; towertalk@contesting.com
>>> Subject: RE: [TowerTalk] grounding quesitons: Ufer, strap, exothermic
>>> welds
>>>
>>>
>>> Jim - what about the inductance of wire? The reading I have done
>>> strongly
>>> suggests that lightning is better handled with solid strap because of
>>> its
>>> low inductance versus wire. Lightning is supposed to be broadbanded with
>>> most energy centered around 1MHz so strap is supposed to be "king" for
>>> the
>>> purposes of dissipating lightning.
>>>
>>> 73,
>>> mat
>>>
>>>> From: w7ry@inbox.com
>>>> To: kk1c@live.com; towertalk@contesting.com
>>>> Subject: Re: [TowerTalk] grounding quesitons: Ufer, strap, exothermic
>>>> welds
>>>> Date: Sun, 17 Apr 2011 07:58:27 -0700
>>>>
>>>> I would put some #2AWG tinned solid in the foundation and not rely on
>>>> the
>>>> rebar.
>>>>
>>>> I have used a clamp type unit to clamp the copper strap to the ground
>>>> rod.
>>>>
>>>> If it's lightning your concerned with, I would not use strap. Stick
>>>> with
>>>> #2AWG tinned bare copper, copper clad rods and exothermic attachment.
>>>>
>>>> 73
>>>> Jim W7RY
>>>>
>>>>
>>>> --------------------------------------------------
>>>> From: "Mat Eshpeter"<kk1c@live.com>
>>>> Sent: Sunday, April 17, 2011 7:24 AM
>>>> To:<towertalk@contesting.com>
>>>> Subject: [TowerTalk] grounding quesitons: Ufer, strap, exothermic welds
>>>>
>>>>> I am about to pour concrete for the base of my HDX589 tower. I am
>>>>> going
>>>>> to
>>>>> go with a Ufer ground as well as the Polyphaser recommended eight 75'
>>>>> radials with multiple ground rods (8' rods every 16'). Location is on
>>>>> top
>>>>> of a 1600' ridge in WV and lightning is a very real concern. My QRZ
>>>>> web
>>>>> page gives a feel for the location.
>>>>>
>>>>> To build the Ufer ground, I am thinking about connecting a single bare
>>>>> 2/0
>>>>> stranded copper wire to the rebar. Questions:
>>>>> 1) is one enough?
>>>>> 2) how do I properly connect the copper to the rebar? Is exothermic
>>>>> weld
>>>>> the only way? Any problem with dissimilar metals?
>>>>> 3) how should the copper exit the base slab - above grade or below
>>>>> grade?
>>>>>
>>>>> Also, seems that copper strap is the preferred ground material for
>>>>> connecting rods together. Will 0.032" thick strap have significantly
>>>>> better longevity than 0.022" strap? I am refering to the strap sold by
>>>>> Georgia Copper. Copper is expensive and I don't want to invest in
>>>>> copper
>>>>> that won't add any value to my installation.
>>>>>
>>>>> Where can I find exothermic weld products to connect copper strap to
>>>>> 5/8"
>>>>> copper clad ground rods? I am exhausted reading Harger, Erico,
>>>>> Terraweld
>>>>> info, and can only find wire-to-ground rod products, no strap-to-rod
>>>>> products.
>>>>>
>>>>> 73
>>>>> Mat
>>>>> KK1C
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> TowerTalk mailing list
>>>>> TowerTalk@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>>>
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