Earth ground resistance tester simplifies grounding, bonding verification of cabling systems

March 5, 2012
Extech Instruments has introduced its GRT300 Ground Resistance Tester.

Extech Instruments (Nashua, NH) has introduced its GRT300 Ground Resistance Tester, designed for testing and validating proper grounding and bonding of new and existing electrical and telecommunications cabling systems. The company says the simplified, plug-and-play design of the GRT300 makes it easy for users to test for compliance with NECA, TIA and BICSI grounding and bonding standards for earth ground resistance using 2-, 3- and 4-point measurements.

Integrated in a rugged and weather-resistant hard carrying case in a high-visibility shade of yellow, the Extech GRT300 is used by installation and maintenance professionals for measuring ground resistance and soil resistivity from 0 to 2000Ω as well as earth voltage measurements (to 300ACV) and grounding-related continuity testing. Auto-ranging automatically identifies the most ideal of four resistance ranges, (2Ω, 20Ω, 200Ω, 2000Ω). Color-matched inputs and large, glove-friendly buttons simplify function selection from 2 to 4 wire testing and AC voltage. A large, two-line dot-matrix LCD screen aids users with easy-to-read instructions and information.

With a Category IV overvoltage safety rating, the company says its GRT300 adds user confidence around outdoor electrical hazards with fused fault protection to 300VAC. Technicians can use the tester for two-point continuity tests; three-point tests for ground resistance readings; four-point tests to identify minimal soil resistivity; and also earth voltage readings. Added features include automatic current and potential spike checks, data hold, auto power off, and a low battery alert.

The Extech GRT300 kit includes 4 alligator-clip test leads, 4 auxiliary earth bars, the integral hard carrying case, and eight 1.5V AA batteries. The GRT300 is also available with certified calibration traceable to NIST standards. To learn more, visit

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