What is the typical imbalance threshold that a ground-fault circuit interrupter monitors for operation?

A ground-fault circuit interrupter (GFCI) is designed to protect against electrical shock by monitoring the current flowing through the circuit. It detects any imbalance between the outgoing and incoming current, which can indicate a ground fault.

The typical imbalance threshold that a GFCI monitors for operation is 4 to 6 mA. This threshold is critical because it is sensitive enough to detect potentially dangerous faults while minimizing the risk of nuisance tripping under normal operating conditions. The chosen range helps ensure that the GFCI can effectively protect users from electrical hazards such as shock, particularly in wet or outdoor environments where such incidents are more likely to occur.

By responding to these small imbalances, GFCIs can quickly disconnect the power to prevent injury, making them essential safety devices in residential, commercial, and industrial settings. Understanding this threshold is key to appreciating how GFCIs function and their role in electrical safety.