NEIEP Mechanics Practice Exam

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Prepare for the NEIEP Mechanics Exam with multiple choice questions, hints, and detailed explanations. Ace your test and advance your career!

Practice this question and more.

Which instrument is used to check a fuse with power removed from the circuit?

Voltmeter
Megohmmeter
Amperemeter
Ohmmeter

The correct answer is: Ohmmeter

The correct choice is an ohmmeter, which is specifically designed to measure resistance in a circuit. When checking a fuse with power removed, you are looking to determine whether there is continuity through the fuse or if it is blown. An ohmmeter applies a small voltage and measures the resulting current to calculate the resistance. If the fuse is good, it will show a low resistance value, indicating continuity. However, if the fuse is blown, it will display a very high resistance or infinite resistance, indicating a break in the circuit. This process is safe because it requires no power, thus eliminating risk to the user and preventing damage to the measuring device. Other instruments, such as a voltmeter, would measure voltage when power is present, making them unsuitable for this task. A megohmmeter is generally used for insulation resistance testing in high-voltage circuits and is also not appropriate for checking a fuse. An ammeter measures current flow when power is applied, which is not applicable for checking the integrity of a fuse in a powered-off state.