What does a Ground Fault Circuit Interrupter (GFI) compare to function properly?

A Ground Fault Circuit Interrupter (GFI) is designed to enhance electrical safety by monitoring the current flowing through a circuit. Specifically, it compares the current flowing into a circuit with the current returning from that circuit. If there is a difference in current flow, it indicates that some current is leaking out, potentially through a person's body or through an unintended path to the ground. This difference can be due to a fault or hazardous conditions, such as when a person touches a live wire. When the GFI detects an imbalance, it quickly cuts off the electrical supply, thereby preventing electrocution or electrical fires.

This operation is crucial for environments where water is present, as the risk of electric shock significantly increases. The ability of a GFI to react to these current imbalances is what makes it a vital safety device in residential and commercial electrical systems.