Understanding how dangerous voltages can develop on a "GROUND" wire can sometimes be helped by understanding lightning as a very extreme surge, a standing wave in electrons looking for some place to go to dissipate.
The force behind the surge is is the lightning of course, and the ground conduction as this surge spreads out is EXTREMELY lumpy, miscellaneous, whatever you want to call it. If lightning hit a tree in your back yard, this pulse is trying to move away from it, taking what ever path it may to get away. One of the paths of conduction for the surge might be from the ground up into a ground rod to a conductor at your feedline entrance, to a "grounding" plate, to the shield of every one of your coax feeds, to the chassis of all your rigs. At this instance your rig cases are high against everything else as the surge takes off down the safety ground wire to the power ground. Connecting the coax entry ground to the power ground with a straight large conductor run gives the surge another EASIER way to go. Avoiding the need for this low impedance shunt path is why a single point ground works. One thing that often gets missed is that a house with its foundation system or basement can be a conduction barrier in the path of the surge's dissipation pulse. If there is a miscellaneous conduction path through/under the house, you want it to be a good one where detours up to sensitive equipment is out of the way and unattractive to the surge. 73, Guy. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
