FLUKE ES165X Earth Spike Test Kit

A ground or earth is a conducting connection, usually between an electrical circuit and the earth. Earth grounding is a connection from a circuit conductor, usually the neutral, to a ground electrode or plate placed in the earth. Equipment grounding ensures that operating equipment or a circuit is grounded properly. This prevents differences in voltage potential from a possible flash-over from things such as lightning strikes by ensuring the current finds a safe path to the earth.
A ground resistance tester is able to take resistance measurements using several test methods, selective testing, stake-less testing, 2-pole testing and 3-4-pole testing. They are able to test the resistance between the earth plate or earth electrode and surrounding ground. In pole testing probes are entered in to the ground and a reading is taken at each location. Readings are then plotted against the distances, the point where the resistance drops is the approximate resistance of the grounding. This is called the fall of potential method and is highly reliable.