Nate Core Practice Test 2026 – Comprehensive Exam Prep

The most important consideration when connecting an ohmmeter to an electrical circuit is that the power source must be disconnected. This is critical because ohmmeters are designed to measure resistance, and any voltage present in the circuit can lead to inaccurate readings and potentially damage the meter.

When the power is on, the circuit is energized, and the current flowing through the components can cause misleading resistance measurements. Additionally, if the ohmmeter is connected to a live circuit, it can create a hazardous situation by introducing high voltages into the meter, potentially damaging it or causing safety risks to the user.

Therefore, ensuring that the power source is completely disconnected before taking resistance measurements helps ensure both the accuracy of the readings and the safety of the equipment and the operator. This fundamental practice is essential for anyone working with electrical testing tools.