[TowerTalk] Lightning Advice

[Jim Brown]

On Tue, 11 Sep 2007 09:49:17 -0700, Bill Turner wrote:

>A good Single Point 
>>Ground (SPG) is essential.

>------------ REPLY FOLLOWS ------------

>I have heard this stated before, but in the case of lightning, I don't
>understand the reason why. I do understand in the case of AC mains
>safety grounding, but not for lightning.

The reason is that bonding all the grounds together minimizes the POTENTIAL 
DIFFERENCE (voltage) between equipment at different locations in your home 
in the event of a strike. Lightning doesn't necessarily hit ONLY one spot, 
it can divide between many paths to earth. This difference causes current to 
flow into the equipment, which is a major way equipment is damaged and/or 
destroyed.  Also, when you provide multiple paths to earth, all tied 
together, you divide the current between them, which in turn reduces the 
voltage drop in each path, and the dissipation in the path. This gives you a 
better chance that the strike might be discharged to a lower voltage before 
the path disintegrates. :) 

73,

Jim Brown K9YC