[TowerTalk] bonding to AC power box or inside fuse panel?

[Jim Brown]

On 1/21/2013 5:10 PM, Dick Green WC1M wrote:
> Some grounding decisions are not straightforward. For example, my AC and telco services are on one side of the house and the station "single-point" ground is on the other side of the house. It would have taken 150 feet of low-inductance wire and at least 10 8-foot ground rods and Cadweld shots to connect the ground systems outside the house. So I decided to bond them together inside the house, using about 25 feet of 1/0 wire. Not the recommended way to do it, but it my opinion a better way to ensure that the ground systems are at the same potential.

Right. I have a similar situation with my shack.  I took a "belt plus 
suspenders" approach -- I ran a bare #6 around the perimeter, bonding it 
to rods by the power panel, at several points around the perimeter, and 
more outside the shack. Inside the shack, I have thinwall steel conduit 
(EMT) between the breaker panel (entrance) and outlets under my 
operating desk, which are, of course, bonded to the panel. My coax panel 
is between those outlets (at floor level) and the operating desk, and 
I've added a bond between the desk, the antenna panel, and the conduit.

> Another example is bonding the tower ground to the single-point ground at the house. My first tower farm is 265' from the house. Being new to tower construction, I laid 265 feet of 1/0 ground wire in the trench running between the two locations in order to bond the ground systems. This was not cheap, to say the least (though it was before the big run up in copper prices.) Later, I read an article by Polyphaser that said if the ground systems are more than 75' apart it does no good to bond them -- the wire inductance will be too high to make an effective connection. With this in mind, when I installed my second tower system in a different location 220' from the house, I did not run a separate ground wire. The Polyphaser argument made sense to me.

Yes, it's good practice, solidly based on fundamental circuit concepts.  
In fact, it's also good to add common mode ferrite chokes to the cables 
running between the towers and the shack to minimize noise coupling.

73, Jim K9YC