On 4/17/2011 10:56 PM, Jim W7RY wrote:
> Pretty difficult to move it once entombed in concrete....
Yah, I'd be surprised if one loosened like that, and more surprised if
some one was finding it. <:-))
I think they call that destructive testing.
73
Roger (K8RI)
>
> 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
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>>
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