Earth Testers

The DET 20 is a reliable 3½ digit LCD meter designed for accurate measurements of earth resistance, soil resistivity, and earth voltage. Thanks to its cutting-edge RSR technology, it delivers stable and precise readings, even when the battery starts to run low. Built tough for heavy-duty tasks and challenging environments, this instrument is your go-to for dependable performance.

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The 128 Hz test frequency of the DET 20 is significant because it minimizes harmonic interference from the power grid. Since standard electrical systems operate at 50 Hz or 60 Hz, using a non-multiple frequency like 128 Hz ensures that stray currents or noise from nearby power lines do not affect the measurements. This results in clean, accurate readings of earth resistance, which are essential for reliable safety and performance assessments.
The DET 20 employs two measurement techniques corresponding to different tests: the 3-wire method is used for Earth resistance testing, while the 4-wire method is used for soil resistivity testing. The 3-wire method is simpler and measures the resistance of an existing grounding electrode. The 4-wire method, also called the Wenner method, is more precise, using four probes to eliminate the resistance of the test leads and electrodes, providing an accurate measurement of the soil’s intrinsic resistivity
The "fall-of-potential" principle is the most common method for measuring earth resistance. This principle works by injecting a known alternating current between the test electrode and a remote auxiliary current electrode. A separate auxiliary potential electrode is then placed at various points in between to measure the voltage drop. The DET 20 applies this method by calculating the resistance (R) using Ohm's Law (R=V/I), where V is the measured voltage drop and I is the injected current.