• Megger

Megger® DET10C & DET20C

Clamp-on Ground Resistance Testers
Megger DET10C/DET20C Earth testers
  • Easy, fast Clamp-on operation – No rods or cables necessary
  • Measures ground resistance from 0.025Ω to 1550Ω
  • Measures ground leakage current from 0.2mA to 35A
  • Auto ranging with high and low alarms


  • Automatic self calibration
  • Extensive data storage and RS232 data download for later analysis (DET20C)
  • Automatically detects continuity in potential and current connections
  • Easy and fast Clamp-on operation. No need for cables or auxiliary rods/stakes.
  • Large LCD display screen that can be read in bright sunlight.
  • Measures ground resistance from 0.025Ω to 1550Ω.
  • Direct reading of continuity and ground loop resistance.
  • Measures ground leakage or phase current from 0.2mA to 25A.
  • Large jaw opening to accommodate a variety of conductors.
  • Indication of high noise content that may affect readings.
  • Lightweight…only 750g (1.65lbs), yet exceptionally rugged for regular field use.
  • Hold function for difficult to reach installations.
  • Auto-off to save on battery power.
  • Configure high and low alarms with audible indication for fast field checks.
  • On board storage of test results (up to 8180 records).
  • Calibration check loop to insure proper operation.
  • Rugged, yet lightweight storage case contains complete testing kit.
  • RS-232 interface for download of test data for later analysis (DET20C).
  • Large jaw opening
  • Measures Ground Resistance from 25 mohm to 1550 ohms
  • Measures Ground Leakage current from 0.2 mA to 35 A
  • Automatic self calibration
  • Auto-ranging
  • High and low alarms
  • Large memory(DET20C only)
  • Download to Megger Download Manager(DET20C only)


The Megger models DET10C and 20C measure earth/ground resistance and current flow using Clamp-on technology. The instruments induce a test current into the system without the need to disturb existing connections. Either unit is a useful addition to the more traditional methods of earth/ground resistance testing that may require disconnection and the use of stakes or ground rods. Simply clamp around the conductor or stake/rod and measure the resistance to ground fast and accurately.

The DET10C and 20C can also be used to measure earth/ground resistance in multiple loop installations without disconnecting the earth or ground. This allows the user to perform the test quickly and easily in total safety, with the added convenience of having a single point of measurement to read the earth/ground resistance.

Each instrument also provides a true RMS current measurement reading to better indicate potential measurement problems and provide a useful overview of the dynamics of the general earth/ground system. The units are rugged, compact and have configurable audible alarms. They also feature auto shutdown (which is also configurable), data storage and self calibration on power-up, and are supplied with a calibration loop – all contained in a rugged carry case. The DET20C also comes with a RS232 interface cable and is compatible with Megger Download Manager Software (included) allowing further analysis and storage of data.

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  • Use to measure resistance and continuity of grounding loops around pads and buildings.
  • Use on multi-grounded systems without disconnecting the ground rod/stake under test.
  • Use to measure leakage current flowing to ground or circulating in ground systems.
  • Use on cell towers, RF transmitters and telecommunications sites.
  • Use to inspect and verify lightning protection systems.
  • Use on a variety of consumer installations, including pools, spas, etc.
  • Literature
  • Specifications
pdf icon Description
++ DET10C/20C Specification sheet (1.6 MB)
Ranges and Accuracies:
Ground Resistance 2
Accuracy 1
0.025 – 0.25 Ω 0.002 Ω ± 1.5% ± 0.05 Ω
0.25 – 9.999 Ω 0.02 Ω ± 1.5% ± 0.1 Ω
10 – 99.99 Ω 0.04 Ω ± 2.0% ± 0.3 Ω
100 – 199.9 Ω 0.4 Ω ± 3.0% ± 1.0 Ω
200 – 400 Ω 2 Ω ± 5.0% ± 5
400 – 600 Ω 5 Ω ± 10% ± 10 Ω
600 – 1550 Ω 20 Ω ± 20%
1 Loop resistance non-inductive, external field <50 A/m, external electrical field <1 V/m, conductor centred in jaws.2 Resistance measurement frequency 1.667KHz
Alarm Type
High Alarm
0 – 1550 Ω
1 Ω
Low Alarm
0 – 1550 Ω
1 Ω
Leakage Current 3 Resolution Accuracy
0.200 – 1.000 mA 0.001 mA 2.0% ± 0.05 mA
1.00 – 10.00 mA 0.01 mA 2.0% ± 0.03 mA
10.0 – 100.0 mA 0.1 mA 2.0% ± 0.3 mA
100 – 1000 mA 1 mA 2.0% ± 3 mA
0.20 – 35 A 0.01 A 2.0% ± 0.03 A
3 Auto range, 50/60Hz, true RMS to crest factor <3.5