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Re: [TowerTalk] Ground wire gauge

To: <TOWERTALK@contesting.com>
Subject: Re: [TowerTalk] Ground wire gauge
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
Date: Sat, 21 Jul 2007 22:52:18 -0400
List-post: <mailto:towertalk@contesting.com>


>
>
> Yes, but why would anyone rely on soldered connections (as for the coax
> shield to braided ground cable)?

Under the proper conditions I would.

> Solder would definitely have the
> highest resistance per unit volume in the whole chain, and it melts when
> it gets hot.  I would think such a connection would be more like a fuse
> that blows before the surge has progressed very far.
>
It maybe the weakest link and it may not, but that does not necessiarily 
make it a problem, particularly in this case.
The area of contact is quite large giving it more than the current carrying 
capability of the shield on one cable. So even if the material (solder) is 
of a higher resistance than the braid, if the area is large enough (and it 
appears to be) then the resistance of the connection is going to be equal to 
or even less than the braid.  A large contact area with copper on each side 
makes for one whale of a good heat sink.  It also comes off at a very 
shallow angle which is recommended. There are also a whole slew of these 
connections in parallel reducing the resistance even farther.

Given the large cross sectional area of the solder connections compared to 
the cross sectional area of the coax (which is quite small),  I'd bet they 
wouldn't fail any sooner than the braid itself from a lighting strike.

Also as this is a safety issue (911 call center in the heart of lightning 
alley) this installation would have had to meet code, so I'd bet it's well 
done.

Roger (K8RI)

> 73,
> Dave   AB7E
>
>
> jacobsen_5@msn.com wrote:
>> Martin wrote:
>> "More copper (and more surface area) for lightning protection are always
>> better, like 4/0.  I ran across an interesting commercial installation
>> here: http://tinyurl.com/2v5sea<http://tinyurl.com/2v5sea> .
>>
>> 73 Martin AA6E"
>>
>> Now THAT was interesting reading!!!!!!!!!!!!!!!!!
>>
>> 73
>> K9WN  Jake
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