NEIEP Mechanics Practice Exam

Which device measures current in a circuit without the need to disconnect wires?

1. Voltmeter

2. Clamp-on meter

3. Ammeter

4. Multimeter

The correct answer is: Clamp-on meter

The device that measures current in a circuit without the need to disconnect wires is a clamp-on meter. This tool works by clamping around a conductor, such as a wire, and uses the principle of magnetic induction to measure the current flowing through that conductor. This is particularly useful for live circuits where you want to avoid any interruption to the electrical flow, ensuring safety and convenience. While a voltmeter is designed to measure voltage, and an ammeter requires a connection in series with the circuit (which involves disconnecting wires), a multimeter can measure various electrical properties, but it typically requires configuration for each measurement and may likewise need to be connected in series for current measurements. The unique design of the clamp-on meter allows for quick and efficient current readings without altering the circuit.