What aspect of a grounding electrode can a ground tester measure?

A ground tester is specifically designed to measure the resistance of grounding electrodes. This functionality is crucial because the effectiveness of a grounding system is often determined by its resistance to soil. A low resistance value is preferred, as it indicates that the grounding electrode can effectively direct fault currents into the earth, thereby improving safety and minimizing the risk of electrical shock or equipment damage.

When measuring resistance, the ground tester accomplishes this by sending a known current through the grounding system and measuring the resulting voltage drop across the electrode. Ohm's Law (Voltage = Current x Resistance) is used to determine the resistance of the grounding electrode, providing critical data for evaluating whether the grounding system meets code requirements and operational needs.

The other aspects listed—voltage, current, and power factor—are not the primary focus of a ground tester. While a ground tester may monitor these variables during the measurement process, the primary and most relevant measurement provided to the user through a ground tester is the resistance of the grounding electrode. This measurement directly informs the effectiveness and reliability of the grounding system.