Final answer:
Among the choices given, the #6 Aluminum wire is most likely capable of being run unsupported over the distance of 4.8 meters considering its larger size and the properties of aluminum versus copper. The aluminum wire needs to have a larger diameter compared to copper when the resistance is the same.
Step-by-step explanation:
To determine which overhead conductor sizes could be run unsupported through the air over a distance of 4.8 meters, we need to consider factors such as the tensile strength, ductility, and electrical characteristics of the materials in question. In this case, the materials are aluminum and copper with various wire gauges.
Considering typical overhead electrical installation standards, larger gauge wires (smaller numbers) tend to have higher tensile strength and can support themselves over longer distances without sagging excessively. Therefore, among the choices given, the larger aluminum conductor (choice C) #6 Aluminum is likely to be capable of being run unsupported over a distance of 4.8 meters. It is important to note that wires are selected based on several factors, including electrical load, distances, and environmental conditions, which are not provided in the question.
When comparing aluminum to copper, given the same resistance, the aluminum wire would need to have a larger diameter because of its higher resistivity. Aluminum is lighter and cheaper but has a lower ductility and tensile strength compared to copper. Additionally, it has a higher rate of thermal expansion, which can create concerns in some installations.