[TowerTalk] Grounding of cables to tower?

[Ward Silver]

This is one of those "what problem are you trying to solve" issues - ac 
safety, lightning, or RF management?

Towers should have an ac safety connection between the tower and the 
station/house ground.  It is permitted by NEC to use coaxial feed line 
shields for that.  Bonding over the long distances doesn't hurt anything 
and if the conductor is buried, acts as another charge dispersing path 
in the soil.  But long conductors aren't much use at RF due to 
inductance (at low frequencies) and impedance (at RF).

The 200' figure was taken from MIL-419A which is the military's cutoff 
for requiring bonding of the tower and building perimeter ground, IIRC.  
You can find other definitions of "too distant for bonding" but 419A 
actually specifies a figure.  There are various references here and 
there to 60', 100', etc but I was unable to find an authoritative 
reference with those figures.

Perhaps one of the more knowledgeable folks here on the reflector can 
add something to that.  Jim Lux's post helps clarify things.

73, Ward N0AX


On 10/18/2017 5:21 PM, towertalk-request at contesting.com wrote:
> A couple of questions:
>
> 1) on page 15 of your referenced document you say a distant tower should not be
> bonded to house (shack) ground and go on to connect the coax shield.? How is
> that not a connection between the two?
>
> 2) Where does 200' come from?
>
> Wes? N7WS
>
>
>
> On 10/17/2017 7:09 PM, Jim Brown wrote:
>> On 10/17/2017 11:39 AM, Bob Shohet, KQ2M wrote:
>>> Please share with me what you would do and why.? Thank you.
>> Why not just buy and study the new ARRL book by Ward Silver, N0AX, which
>> covers all of this, and to which I contributed?? Or "Up the Tower" by K7LXC,
>> for which I contributed the chapter on Grounding. Or study the slides for the
>> talk on Power and Grounding for Ham Radio that I've given at Pacificon and the
>> Visalia DX Convention?
>>
>> http://k9yc.com/GroundingAndAudio.pdf
>>
>> 73, Jim K9YC