What is one reason to use a voltage tester?

Using a voltage tester is primarily intended to verify if a circuit is live or dead, which is crucial for ensuring safety when working with electrical systems. This tool allows electricians and other professionals to check whether there is voltage present in a circuit, confirming that it is safe to work on. If the tester indicates that the circuit is live, precautions can be taken to de-energize the circuit before performing any maintenance or repairs, reducing the risk of electrical shock or accidents.

The other options involve different aspects of electrical measurement that a voltage tester is not designed for. Measuring current flow typically requires a different tool, such as a multimeter set to measure current. Checking the frequency of electricity also falls outside the functionality of a standard voltage tester, as this would require specialized equipment like an oscilloscope or a frequency meter. Monitoring energy consumption is similarly unrelated, as this involves measuring the amount of power used over time, typically done with energy meters or data loggers, rather than a voltage tester.