Which instrument could be used to test the continuity of the case ground on a portable drill?

Which instrument could be used to test the continuity of the case ground on a portable drill?

• A. Voltmeter
• B. Ammeter
• C. Volt-Ohm Meter
• D. Megger

Answer: (C)

Testing the continuity of the case ground means confirming there is an unbroken, low-resistance path from the drill’s metal casing to the grounding path. A device that can measure resistance and indicate continuity is needed. A volt-ohm meter does exactly this: in resistance or continuity mode it checks how easily current can flow along the ground path. If the case is properly grounded, you’ll see a very low resistance (often with an audible beep). If the path is open or broken, the reading will be high or there will be no beep. In contrast, a voltmeter measures voltage and won’t tell you whether the casing is connected to ground. An ammeter measures current and also doesn’t assess continuity. A megger tests insulation resistance by applying a high voltage to detect leakage, not to verify a grounding path. So the volt-ohm meter is the appropriate instrument for confirming case-ground continuity.

Testing the continuity of the case ground means confirming there is an unbroken, low-resistance path from the drill’s metal casing to the grounding path. A device that can measure resistance and indicate continuity is needed. A volt-ohm meter does exactly this: in resistance or continuity mode it checks how easily current can flow along the ground path. If the case is properly grounded, you’ll see a very low resistance (often with an audible beep). If the path is open or broken, the reading will be high or there will be no beep.

In contrast, a voltmeter measures voltage and won’t tell you whether the casing is connected to ground. An ammeter measures current and also doesn’t assess continuity. A megger tests insulation resistance by applying a high voltage to detect leakage, not to verify a grounding path. So the volt-ohm meter is the appropriate instrument for confirming case-ground continuity.