ARRL Technician Practice Exam

Which of the following precautions should be taken when measuring high voltages with a voltmeter?

1. Use low-voltage probes

2. Ensure that the voltmeter and leads are rated for use at the voltages to be measured

3. Perform measurements in a wet area

4. Adjust the meter to a higher current range

The correct answer is: Ensure that the voltmeter and leads are rated for use at the voltages to be measured

When measuring high voltages, it is crucial to ensure that the voltmeter and its leads are rated for the specific voltages you intend to measure. This is essential for both safety and accurate measurement. High-voltage applications can be hazardous, and using equipment that is not properly rated for those voltages can lead to equipment failure, inaccurate readings, or potentially dangerous situations, including electric shock or burns. The safety ratings of voltmeters and probes are designed to handle specific voltage levels, often marked on the device itself. Utilizing equipment that meets or exceeds the necessary safety ratings provides a protective measure that helps ensure the user can conduct measurements safely and effectively. In contrast, the other choices present potential risks or impracticalities. Using low-voltage probes would not be safe for high-voltage applications. Measuring in wet areas is highly discouraged due to increased risks of electrical accidents. Adjusting the meter to a higher current range is irrelevant when measuring voltage, as it does not affect the ability to correctly measure voltage levels.