Final answer:
A GFCI for personnel protection operates when it senses a current imbalance between 5 mA and 30 mA. It compares the currents in the live/hot and neutral wires and trips if the leakage current exceeds the safe limit.
Step-by-step explanation:
A GFCI (ground fault circuit interrupter) for personnel protection operates when it senses a current imbalance between 5 mA and 30 mA. It compares the currents in the live/hot and neutral wires. When the live/hot and neutral currents are not equal, it indicates that there is a leakage current. The GFCI is designed to trip and interrupt the circuit if the leakage current exceeds the accepted safe limit, which is typically set at around 5 mA.