What is an Earth Ground Tester?

• A. device used to test resistance of grounding rods
• B. an instrument for measuring current in circuits
• C. a device for testing insulation resistance
• D. a thermocouple reader

Answer: (A)

An Earth Ground Tester measures the resistance of an earth grounding system, typically the grounding rod or electrode and its connection to the surrounding soil. This is essential because a low-resistance path to earth ensures fault currents are quickly diverted away from equipment and people, allowing protective devices to trip reliably and reduce the risk of shock or damage. The tester usually works by injecting a known current into the ground and measuring the resulting voltage (or by using a three-point/four-point method) to calculate ground resistance. It is specifically about assessing how effective the earth ground is, not about measuring current in a circuit, testing insulation between conductors and ground, or reading temperatures from a thermocouple. Those other devices perform different tests, such as measuring circuit current, insulation resistance, or temperature.