What is the primary use of a multi-meter?

A multi-meter is primarily used to measure voltage, current, and resistance, making it an essential tool for electricians and linemen. This versatile instrument allows users to assess the electrical characteristics of circuits, which is critical for troubleshooting, ensuring safety, and verifying circuit functionality.

By measuring voltage, the multi-meter helps determine if electrical potential is present in a circuit. Current measurement aids in assessing how much electricity is flowing, which is vital for understanding load characteristics and diagnosing issues. Resistance measurement is used to check circuit integrity, identify faulty components, and ensure connections are properly insulated.

The other options relate to different tools or specific applications that do not cover the broad functionality that a multi-meter offers in electrical measurements.