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EM 4058

EM 4058

The EM4058 earth tester is a digital, microprocessor controlled instrument that allows to measure the earth resistance and ground resistivity (using Wenner´s method), as well as to detect parasitic voltages present in the ground. This instrument is suitable to measure earth systems in power substations, industries, distribution networks, etc., according to IEC 61557-5.

It is also suitable for soil resistivity measurements, in order to optimize the earth systems project. It is a fully automatic and easy-to-operate equipment. Before starting each measurement, the equipment will check that conditions are within appropriate limits and will notify the operator in case any abnormality turns up (too high interference voltage, too much resistance in test spikes, very low test current, etc). Then, it will look for the most suitable range and show measurement results in an alphanumeric display.

The EM4058 has a Frequency Scan feature that performs an earth resistance measure with all vailable frequencies automatically and calculates, displays and prints the average result besides the individual result of each frequency. Those results are saved on the internal memory. 

The instrument has four ranges that are automatically selected, covering measurements from 0.01 Ω up to 20 kΩ, which allows to obtain very accurate measurements for any kind of soils. During ground resistivity measurement, the operator may indicate the distance between spikes in order for the equipment to apply Wenner's formula and to show the resistivity value directly. 


  • Earth resistance measurement
  • Ground resistivity (Wenner's method)
  • High spurious voltage rejection
  • Spurious voltage measurement
  • Measure with multiples frequencies (270 Hz, 570 Hz, 870 Hz, 1170 Hz, 1470 Hz)
  • 0.01 Ω resolution
  • Up to 20 kΩ resistance range
  • Remote control through an Android App
  • Auto-range
  • Built-in memory
  • Built-in printer
  • USB interface


Parameters EM 4058 
Measurement ranges Resistance (Autoranging) - 0 – 20 KΩ, Resistivity 0 – 50 KΩm Voltage  0 – 60 V AC
Measurement Accuracy Resistance ± 2% of Reading ± 2 Digit Voltage ± 3% of Reading ± 2 Digit
Measurement Resolution Resistance - 0.01 Ω, Resistivity 0.01Ωm Voltage – 0.1 V
Operation Frequency 

270 Hz (resistance or resistivity measurement)

570 Hz, 870 Hz, 1170 Hz or 1470 Hz (resistance measurement)

Power Supply  Internal Rechargeable LiFePO4 battery 
Operating temperature -10˚C to 50˚C
Equipment Weight Approximately 3 Kg 
Interface  USB 
Dimensions 274 x 250 x 124 mm


Read 5892 times Last modified on Tuesday, 25 September 2018 12:21

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