[TowerTalk] Single point ground question

[Jim Brown]

On Fri, 23 Oct 2009 13:47:52 -0400, Jerry wrote:

>The forum moderator is a guy by the name of IDRick and he seems to think
>that the most logical choice is to have the antenna as close to the power
>lines as possible and have the ground as short as possible, and hopefully
>the lightning will take the shortest route to ground.

The forum moderator is absolutely correct. Several fundamental principles 
apply. First, ALL grounds MUST be bonded together for safety, and they 
should be bonded together by the shortest practical path. This includes 
the power system ground (where power enters the building), as well as 
grounds for telephone lines, cable TV, and any antennas (including a 
dish). Short is critical to minimize inductance, because most of the 
energy in lightning is in the 500kHz to 5 MHz spectrum. That's why having 
all those cables enter next to power is the best way to do it. 

Separate ground rods that aren't bonded together are a dumb idea, they are 
UNSAFE, they are prohibited by building codes almost everywhere in the 
developed world, and they don't make audio or video systems work any 
better. 

For a tutorial on Power and Grounding for audio and video systems, see 

http://audiosystemsgroup.com/EU-SurgeXPowerGround.pdf 

This tutorial also includes many practical recommendations for minimizing 
hum, buzz, and RFI in audio and video systems without buying expensive 
"power conditioners" and magic boxes. 

Regards,

Jim Brown K9YC
Audio Systems Group, Inc.
Chair - AES Technical Committee on EMC
Vice-Chair - AES Standards Committee Working Group on EMC