Which of the following materials is not suitable for tracer wire?

Tracer wire is commonly used in underground utilities to help locate underground structures by being detectable by a locating device. Suitable materials for tracer wires must conduct electricity and provide reliability in terms of signal detection.

Plastic is not suitable for tracer wire because it does not conduct electricity. For effective tracing of underground lines, the wire must allow for electromagnetic signals to travel along its length. Stainless steel, aluminum, and copper are all conductive metals that can carry these signals, making them appropriate materials for this purpose.

While the other metals can corrode under certain conditions, they still serve the primary function of being able to transmit a signal effectively, whereas plastic lacks the necessary conductive properties, rendering it ineffective for tracer wire applications.