Which of the following is not considered a circuit protection device?

Circuit protection devices are essential components in electrical systems designed to safeguard circuits from overcurrent, overloads, or short circuits. These devices automatically interrupt the electrical flow when they detect unsafe conditions, thus preventing damage to the electrical components and reducing the risk of fire hazards.

Fuses and circuit breakers both serve as primary circuit protection devices. A fuse contains a metal conductor that melts when excessive current flows through it, thereby opening the circuit. Circuit breakers act as automatic switches that trip to interrupt the flow of current in case of a fault condition but can be reset after the issue has been resolved. Relays, while primarily functioning as control devices that allow a small current to control a larger current, can also incorporate protective characteristics by opening or closing circuits under specific conditions.

In contrast, shielded wire is primarily utilized for reducing electromagnetic interference and protecting signal integrity in electrical wiring rather than serving as a circuit protection device. Its primary purpose is to safeguard the conducted signals rather than to disconnect or interrupt the flow of electricity in response to fault conditions. Thus, shielded wire does not fit the definition of a circuit protection device, which is why it is considered the correct answer in this context.