Testing how well a copper bonded earthing rod works after it's been installed is really important to make sure your grounding system is doing its job in keeping things safe. The main way to check its performance is through an electrical resistivity test. This test measures the resistance between the rod and the earth around it. Typically, this is done with a four-terminal (or four-wir... https://www.pioneerpowers.com/copper-bonded-earth-rod.php