So my neighbor had a massive lighting hit and suffered a shit ton of damage about a month ago. He has a big place and is wealthy so he located a lightning protection specialty company that is re-doing his whole estate in a first class way. So with this work going on now, they are leaving on premises a very expensive clamp-around earth ground tester. I have never seen or heard of these before. They are like $1,500 and up. Simply clamp around your ground wire and it calculates and gives an Ohms-To-Earth reading. Obviously the lower the reading the better. I wanted to know how these things work so I googled "how do clamp-around earth ground testers work" Went right to this article which shows such a meter in operation and gives other helpful tips. You may want to read the article and watch the video. A good point in the article described proper ground rod spacing. In short, the "effective energy dispersal radius" of a ground rod is equal to it's depth into the ground. So for a standard 5/8" copper-clad steel 8' rod .... if driven 8' into the ground, it's energy dispersal radius will be 8 feet. They state it is not good to overlap multiple rod's radii - so as an example if you have 2 or more 8' rods connected together of course, they need to be 16 feet apart from each other.
electrical-engineering-portal.com
The easiest way to measure ground resistance using clamp meter, but be carefull! | EEP
The ground clamp meter / tester is an effective and time-saving tool when used correctly because the user does not have to disconnect the ground system
