The Extech GRT300-NISTL is a professional-grade ground resistance tester built for reliability and versatility across a wide range of electrical environments. With its ability to perform 2-wire, 3-wire, and 4-wire testing, it delivers flexible and accurate measurement of earth ground resistance and soil resistivity, critical for verifying grounding system performance in industrial, utility, and telecom settings.
This handheld unit features a user-friendly interface and a high-visibility LCD screen, simplifying operation even in complex installations. Integrated functions such as automatic zero adjustment, test hold, autoranging, and automatic spike checks for both current (I) and potential (P) help ensure accurate, repeatable results with minimal setup. It also includes data hold and auto power-off for added convenience during fieldwork.
Certified with a Limited NIST Calibration, the GRT300-NISTL ensures dependable performance aligned with calibration standards, making it a trustworthy instrument for engineers, electricians, and safety professionals.
What's Included:
- 1 - NIST Certificate of Limited Calibration
- 1 - Set of Test Leads With Alligator Clips
- 4 - Auxiliary Earth Bars
- 1 - Hard Carrying Case
- 8 - 1.5V AA Batteries
Features
Multiple Testing Modes
Supports 2-wire, 3-wire, and 4-wire configurations for ground resistance and soil resistivity measurements in diverse field conditions.
Automatic Spike Check
Built-in verification of I (current) and P (potential) spikes ensures proper probe placement and reliable test results.
Intuitive Test Hold Function
Allows users to freeze readings for easier review and safer handling during testing.
Advanced Functionality
Autoranging, automatic zero adjustment, and data hold functions improve accuracy and usability on-site.
AC Earth Voltage Measurement
Detects AC earth voltage for comprehensive grounding diagnostics.
Status Indicators
Features overrange and low battery alerts to ensure continuous and safe operation.
Limited NIST Calibration
Comes with a limited NIST certificate for traceable accuracy and regulatory compliance.
What's Included
Included with Your Purchase:
- 1 - NIST Certificate of Limited Calibration
- 1 - Set of Test Leads With Alligator Clips
- 4 - Auxiliary Earth Bars
- 1 - Hard Carrying Case
- 8 - 1.5V AA Batteries
Specifications
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Test Methods: 2-wire, 3-wire, and 4-wire
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Resistance Range: 2 to 2000 Ohms
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Display: Backlit LCD screen
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Functions: Autoranging, Automatic Zero, Data Hold, Auto Power Off
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Voltage Measurement: AC Earth Voltage detection
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Indicators: Overrange and low battery status
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Power Supply: 8 x 1.5V AA batteries
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Calibration: Limited NIST Certificate included
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Portability: Compact design with hard carrying case
FAQ
Q: What types of testing does this device support?
A: The Extech GRT300-NISTL supports 2-wire, 3-wire, and 4-wire ground resistance and soil resistivity testing.
Q: Is this model calibrated?
A: Yes, it includes a Limited NIST Calibration Certificate for traceable measurement accuracy.
Q: Does it measure AC earth voltage as well?
A: Yes, it can detect AC earth voltage for a complete grounding analysis.
Q: What happens if the battery is low or the test is out of range?
A: The unit provides clear overrange and low battery indicators for safe and reliable use.
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