What is the Extech GRT300 4-Wire Earth Ground Resistance Tester?
The Extech GRT300 is a professional earth ground resistance tester designed for UK electricians and electrical engineers carrying out earthing verification on commercial, industrial and utility installations. Supporting 2-wire, 3-wire and 4-wire testing, it provides accurate earth resistance measurements for commissioning, periodic inspection and fault investigation.
Ideal for substations, distribution boards, lightning protection systems and ground rods, the GRT300 delivers dependable results across a wide resistance range, with automatic spike checks to confirm correct test setup before measurements begin.
How does the GRT300 support reliable earthing tests?
With built-in automatic current and potential spike checks,the GRT300 helps electricians confirm correct probe placement before testing, reducing re-tests and saving time on site. The large dual-line LCD clearly displays resistance and earth voltage readings, while autoranging simplifies operation across varying ground conditions.
Its robust carry case and full accessory kit make it a practical choice for field work where reliable earth testing is essential.
Test leads for 2 wire 3 wire and 4 wire measurements
Earth test spikes and connecting bars
Hard carrying case
AA batteries
User manual
Why choose Instrotech for your electrical test equipment?
With over 40 years’ experience supporting UK electricians, technicians and engineers, Instrotech is your trusted partner for quality tools and expert service. When you purchase from us, you benefit from:
Free UK shipping on orders over £99
Access to our knowledgeable technical support team
Available calibration services to maintain safety compliance
A 90-day money-back guarantee for complete peace of mind
We’re committed to helping you work safely and efficiently with industry-leading products and ongoing support.
