2 and 3 Point Ground Resistance Meters from Megger

Megger DET3TD Digital Ground TesterWith the advancement in ground resistance measurement technologies, much of the test equipment currently available for this purpose now provide the convenience of Clamp-On technologies that are in some applications preferable to the traditional 2-3 point testing methods. These clamp-on ground resistance meters provide the potential to save valuable time and effort by inducing a current into the ground through electromagnetic coupling. The jaws then sense the voltage drop around the loop and automatically calculate the ground resistance using Ohm’s Law.


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However, depending on the application, clamp-on test equipment may provide slightly less accurate results than traditional technologies. For this reason, it is not recommended to use clamp-on testers to commission new grounds because in many instances there is no return path for the current since it has not yet been connected to the grounding system. Additionally, Clamp-on meters are not able to test complex ground systems where there is a continuous metallic loop.  The test current will simply flow through the conductor and not flow through the soil. Other ground systems that may not be suitable for clamp-on ground testing are high interference environments such as substations and grounding systems that have multiple interconnections or ring grounds.

If you need a ground resistance test set capable of performing measurements in a variety of applications and environments, consider a test set capable of performing the traditional 2-3 point measurements. In doing so, you can be sure that the results are both accurate and reliable.

The Megger Models DET3TD and DET3TC offer a complete solution for ground resistance testing. These units incorporate 2-3 terminal testing capabilities and a ground resistance range of 0.01 Ω to 2000 Ω. Here is a short comparison of these two test sets to help aid in understanding the capabilities of each model and selecting the one that best suits your application requirements.

Megger DET3TD Digital Ground Tester

This tester is designed to be tough to withstand the harsh conditions of outdoor testing. This Megger meter has a large LCD screen that is viewable in dim and brightly lit environments.

  • 2-3 point ground tester with a large selector switch for easy operation
  • Easy to read LCD display and thumb sized button
  • Automatically checks and displays the the C and P spikes’ connection status
  • Integrated voltmeter
  • Selectable 25-Volt or 50-Volt output voltage
  • 0.01 Ω up to 2000 Ω resistance range
  • Internal noise filter that can reject up to 40 Volts peak to peak electrical interference
  • Powered by 8 AA batteries
  • 128 Hertz test frequency at 450 μA/4.5 mA
  • Noise checking feature
  • CAT IV 100 V safety rating
  • Resistance accuracy of 2% ± 3 digits 
  • Ingress Protection 54 rating

Megger DET3TC Digital Ground Tester

This Megger tester offers everything you need in one kit for testing ground rod resistance. It is easy to use and has an optional clamp that lets provides the capability of performing Artificial Rod Testing. This features prevent the need to disconnect the rod from the grounding system while performing ground resistance measurements.

  • 2-3 point ground tester with a large selector switch for easy operation
  • Uses the Attached Rod Technique for testing ground connections
  • Easy to read LCD display and thumb sized button
  • Automatically checks and displays the the C and P spikes’ connection status
  • Integrated voltmeter
  • Selectable 25-Volt or 50-Volt output voltage
  • 0.01 Ω up to 2000 Ω resistance range
  • Internal noise filter that can reject up to 40 Volts peak to peak electrical interference
  • Powered by 8 AA batteries
  • 128 Hertz test frequency at 450 μA/4.5 mA
  • Noise checking feature
  • CAT IV 100 V safety rating
  • Resistance accuracy of 2% ± 3 digits 
  • Ingress Protection 54 rating

Related electrical test equipment available for rent from Protec:

Amprobe DM-III Multitest Power Quality Recorder

Bender LT3000 Line Isolation Monitor (LIM) and GFCI Tester

Fluke 1625-2 GEO Earth Ground Tester

This electrical test equipment is available for rent, lease, or purchase from Protec Equipment Resources. We are here to help you with your testing equipment needs.

Protec’s Calibration Lab offers accurate and affordable calibration services for all makes and models of electrical test and measurement equipment. Contact us today for a quote.


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Editor’s Note: This post was originally published on June, 2012 and has been updated freshness, accuracy and comprehensiveness.