What aspect of current flow does a ground fault circuit interrupter specifically monitor?

A ground fault circuit interrupter (GFCI) specifically monitors current imbalance because it is designed to detect differences between the current flowing into a circuit and the current returning from that circuit. Under normal operating conditions, the current should be equal; if there is a fault, such as a ground fault, a portion of the current may be leaking to the ground instead of returning through the circuit. This imbalance can indicate a potential shock hazard.

When a GFCI detects this current imbalance, it quickly interrupts the circuit, providing protection against electric shock or fire. This functionality is crucial for enhancing safety in environments where electrical devices might come into contact with water, such as bathrooms and kitchens.

In contrast, monitoring voltage fluctuations, resistance levels, or wattage consumption is not the primary focus of a GFCI. These aspects do not directly relate to the immediate safety measures that the GFCI is designed to provide in protecting individuals from electrical hazards.