Which device serves as a preventive measure against accidental electrocution?

A Ground Fault Circuit Interrupter (GFCI) is specifically designed to serve as a preventive measure against accidental electrocution. It continuously monitors the current flowing through the circuit and can detect any imbalances between the current coming in and the current going out. If it senses that the current is flowing through an unintended path, such as through a person who may be in contact with the ground, it trips the circuit almost instantaneously, cutting off the electrical flow. This rapid disconnection significantly reduces the risk of serious injury or death from electric shock.

In contrast, while a fuse can protect electrical circuits by breaking the circuit under overload conditions, it does not specifically address ground faults or protect individuals from electrocution. A transformer is used to change voltage levels, and a surge protector is designed to protect electrical devices from voltage spikes, but neither of these provides protection against ground faults that can lead to electrocution. Therefore, the GFCI is the device that most directly contributes to safety by preventing accidental electrocution.