What is a clamp meter and when is it used?

A clamp meter measures current without breaking the circuit by using a clamp-on current transformer (for AC) or Hall effect sensor (for AC and DC). The conductor passes through the clamp jaws which form a magnetic core. Current creates magnetic field detected by the sensor. Advantages include: non-intrusive measurement, safety (no circuit interruption), and ability to measure high currents. Used for measuring motor current, verifying circuit loads, and troubleshooting. Modern clamp meters also measure voltage, resistance, and power quality parameters.