Jerry hit upon another major point. The grounding methodology cannot be
separated from the quality or lack of quality of earth resistance in the
local earth. What works on the Iowa plains will not work in the rocky Texas
Balcones escarpment. Very poor soil conductivity means that simple putting
in a simple or minimal ground rod system is insufficient earth coupling or
low enough spreading resistance to dissipate direct hits.
Here we use shallow burial ring grounds to supplement the rods of the
electrical and telecommunications safety codes. In the rocky or low
conductivity soils of desert or extreme tropics it may take a field of 10
ground rods to do what one does in good earth areas.
-Stuart
K5KVH
|