What is a "jumper" wire or "pigtail" used for?

A "jumper" wire, often referred to as a "pigtail," is specifically used for connecting wires, particularly in situations where a grounding wire needs to be securely attached to an outlet box. This practice ensures that the electrical system is safe by providing an effective path to ground in case of a fault. Grounding is crucial for preventing electrical shock hazards, and utilizing a pigtail for this connection allows for a reliable and straightforward installation.

In contrast to the other options, the function of a jumper wire is not typically aimed at connecting multiple circuits or serving as a fuse replacement. It's also distinct from simply extending the length of a wire, as that would typically involve joining wires rather than making specific connections to a grounding point. Pigtails are valuable for maintaining the integrity of electrical systems by ensuring that grounding is firmly established, thus enhancing overall safety.