The “Earth Electrode,” also known as ground electrode, provides an electrical connection to earth. The impedance of an electrode determines how quickly and at what potential energy is equalized. The resistance value is determined by the resistivity of soil with which these electrodes are in contact. Current must pass through the soil to the assumed earth potential of 0 Ω.
When an object is grounded, it is forced to assume the same zero potential as the earth. If the potential of the grounded object is higher or lower, current will pass through the grounding connection until the potential of the object and earth are the same. The earth electrode is that connection path to the earth.
The resistance of the electrode, measured in ohms, determines how quickly and at what potential energy is equalized. Upper and lower soil levels typically have different inherent resistivity. Grounding materials and electrodes can take advantage of lower resistivity soil conditions in one or the other layer to minimize materials, maximize performance, and meet ground system resistance goals.