Stakeless measurement The Fluke 1630-2 FC Earth Ground Clamp is able to measure earth ground loop resistances for multi-grounded systems using the stakeless test method. This test technique eliminates the dangerous and time consuming activity of disconnecting parallel grounds, as well as the process of finding suitable locations for auxiliary ground stakes. You can also perform earth ground tests in places you have not considered before: inside buildings, on power pylons or anywhere you don’t have access to soil.
With this test method, earth ground clamp is placed around the earth ground rod or the connecting cable. Earth ground stakes are not used at all. A known voltage is induced by one side of the clamp jaw, and the current is measured by the other side of the clamp jaw. The clamp automatically determines the ground loop resistance at this ground rod. This technique is especially useful for multi-grounded systems typically found at commercial facilities or industrial locations. If there is only one path to ground, like at many residential situations, the Stakeless method will not provide an acceptable value and the Fall-of-Potential test method must be used.
The Fluke 1630-2 FC works on the principle that in parallel/multi-grounded systems, the net resistance of all ground paths will be extremely low as compared to any single path (the one under test). So, the net resistance of all the parallel return path resistances is effectively zero. Stakeless measurement only measures individual ground rod resistances in parallel to earth grounding systems. If the ground system is not parallel to earth then you will either have an open circuit, or be measuring ground loop resistance.