Skip to content

The 3-Point Ground Resistance Measurement

  • Uncategorized

Megger DET62D Ground Resistance Test KitThe three-point or fall of potential method is one of the techniques carried out to determine ground resistance. This method uses three poles where the potential difference is measured on points X and Y while current is applied in points X and Z. Using Ohm’s Law, E=RI or R=E/I, you can obtain the ground stake resistance. three-point or fall of potential method ground testing

The proper spacing of the electrodes is the key in precise ground resistance measurement. The auxiliary electrode Z should be far enough from the ground pole (X) under test. This is to ensure that the potential probe Y is outside the effective areas of resistance of both the auxiliary current rod Y and ground rod X.  To determine if the potential rod Y is outside an effective resistance area, move between X and Z and take a reading at each point. The values should not significantly vary and should be close to each other.

Contact Us Now

For ground testing and other electrical test equipment needs, consider Protec.

Our extensive inventory features a wide range of testers from top brands like AEMC, Amprobe, Fluke and Megger. 

Related electrical test equipment available for rent from Protec:

AEMC 6416 Clamp On Ground Resistance Tester

Amprobe DM-III Multitest Power Quality Recorder

Fluke 1625-2 GEO Earth Ground Tester

Megger DET62D Ground Resistance Test Kit

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.

Editor’s Note: This post was originally published on September 10, 2012 and has been updated freshness, accuracy and comprehensiveness.

Get a Quote Today