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EM4058 Earth Ground Tester

The EM4058 is a microprocessor-controlled, digital earth tester designed for precise measurement of:

  • Earth resistance

  • Ground resistivity (Wenner method)

  • Parasitic/spurious voltages in the soil

Compliant with IEC 61557-5, this instrument is ideal for use in power substations, industrial installations, distribution networks, and any environment requiring high reliability and accuracy.

Key differentiators of the EM4058 include:

  • Multiple selectable test frequencies (270 Hz to 1470 Hz) for different field conditions

  • Automatic range detection and anomaly alerting

  • High spurious voltage immunity (up to 7 V~ with <10% error)

  • Automated soil resistivity calculations

  • Built-in memory and printer

  • USB data export and Android remote control app

Designed for rugged field use, the EM4058 operates reliably in extreme environments and provides a robust, all-in-one solution for ground testing professionals.

Key Features

  • Earth resistance testing up to 20 kΩ

  • Soil resistivity testing with automatic Wenner formula calculation

  • Multi-frequency resistance testing: 270 / 570 / 870 / 1170 / 1470 Hz

  • Frequency scan: tests at all frequencies with average and individual results

  • Spurious voltage detection up to 60 V~

  • Automatic detection of poor test conditions (e.g. high spike resistance, low test current)

  • High tolerance to interference and noise

  • USB interface and built-in printer

  • Remote control via Android app

  • Rugged IP65-rated housing (closed lid)

  • Rechargeable LiFePO₄ battery (LFP), environmentally friendly and long-lasting

Technical Specifications

Category Specification
Test Frequencies 270 Hz, 570 Hz, 870 Hz, 1170 Hz, 1470 Hz
(±1 Hz variation)
Resistance Ranges 0–20 Ω, 0–200 Ω, 0–2000 Ω, 0–20 kΩ (auto-ranging)
Resistivity Range 0–50 kΩ·m (auto-ranging)
Voltage Range 0–60 V~
Resistance Accuracy R ≤ 2 kΩ: ±2% ± 2 digits
R > 2 kΩ: ±5% ± 2 digits
Voltage Accuracy ±3% ± 2 digits
Resolution 0.01 Ω (resistance)
0.01 Ω·m (resistivity)
0.1 V (voltage)
Output Current (Short Circuit) < 20 mA RMS (IEC 61557-5 compliant)
Spurious Voltage Immunity Tolerates up to 7 V~ with <10% error
Auxiliary Rod Resistance Tolerance Up to 50 kΩ with <30% error
Data Storage Internal memory with built-in printer
Interfaces USB port
Remote via Android app
Power Supply 12 V 3000 mAh LFP (LiFePO₄) battery
Battery Charger AC adapter: 12 V, 2.0 A
Standards IEC 61010-1
IEC 61326-1
IEC 61000-4-2 (ESD)
IEC 61000-4-3 (EM immunity)
Overvoltage Protection CAT II, 300 V
IP Rating IP65 (lid closed)
Operating Temperature -10 °C to 50 °C (14 °F to 122 °F)
Storage Temperature -25 °C to 70 °C (-13 °F to 158 °F)
Humidity 95% RH (non-condensing)
Dimensions (W × H × D) 274 × 250 × 124 mm (10.78" × 9.84" × 4.88")
Weight Approx. 3 kg (6.61 lbs)

Included Accessories

  • 4 steel ground rods

  • AC adapter

  • Cable reels:

    • 131 ft (40 m) red cable

    • 65 ft (20 m) blue cable

    • 65 ft (20 m) green cable

  • 16 ft (5 m) black cable

  • 16 ft (5 m) green ground cable

  • Connection wire for 12 V external power (e.g., car battery)

  • User guide

  • 2 durable carrying bags (equipment + accessories)

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