To identify a ground fault in a circuit, which test instrument is most appropriate?

To identify a ground fault in a circuit, which test instrument is most appropriate?

• A. Ammeter
• B. Ohmmeter
• C. Voltmeter
• D. Clamp meter

Answer: (B)

To identify a ground fault, you need to verify whether there is a conductive path from a live part to earth. The most direct way to reveal that path is by measuring resistance to ground with an ohmmeter. When you check between the suspect conductor (or equipment and its ground) and earth, a low resistance reading indicates a fault path to ground. If the circuit is healthy, you’ll see a high or infinite resistance, meaning no continuous path to ground. An ammeter only measures current and doesn’t show whether a ground path exists. A voltmeter measures voltage, which can hint at a fault but doesn’t identify a grounding path or its continuity. A clamp meter measures current around a conductor without breaking the circuit, and it isn’t used to confirm a ground fault path. For safe resistance measurements with an ohmmeter, power must be off and the circuit properly isolated.

To identify a ground fault, you need to verify whether there is a conductive path from a live part to earth. The most direct way to reveal that path is by measuring resistance to ground with an ohmmeter. When you check between the suspect conductor (or equipment and its ground) and earth, a low resistance reading indicates a fault path to ground. If the circuit is healthy, you’ll see a high or infinite resistance, meaning no continuous path to ground.

An ammeter only measures current and doesn’t show whether a ground path exists. A voltmeter measures voltage, which can hint at a fault but doesn’t identify a grounding path or its continuity. A clamp meter measures current around a conductor without breaking the circuit, and it isn’t used to confirm a ground fault path. For safe resistance measurements with an ohmmeter, power must be off and the circuit properly isolated.