Final answer:
Leakage currents must be kept below safety thresholds to prevent risks of shock or fire, with GFIs tripping if the difference in live and neutral wire currents exceeds safe levels, usually in the milliamp range.
Step-by-step explanation:
Leakage currents in an electrical circuit must be kept under a threshold that ensures safety and prevents the risks of shock or fire. Devices like a ground fault interrupter (GFI) are critical for this purpose. The GFI monitors the currents in the live/hot and neutral wires, tripping to cut off the circuit if the difference (which would indicate a leakage current) exceeds a safe value. This value is typically in the range of milliamps, often set at a maximum of 5-6 mA for consumer GFIs.
Furthermore, circuit protection devices like fuses and circuit breakers are designed to limit the overcurrent, allowing for momentary high currents during the 'inrush' period, such as when a light bulb is turned on, or an electric motor starts. However, the overall circuit design should prevent continuous excessive currents to avoid damage or danger.
Kirchhoff's laws also play a role in understanding circuit behavior. Charge conservation implies that at a junction, the sum of currents entering must equal the sum flowing out, ensuring that in a fault-free circuit, leakage currents are minimal and within safe limits.