What does it indicate if a wire is getting too hot?

When a wire is getting too hot, it typically indicates that there is a higher-than-normal current flow through it. Wires are designed to carry a specific amount of current; when the current exceeds this rated capacity, it generates excess heat due to the electrical resistance of the wire material. This heat buildup can compromise the wire's insulation and potentially lead to electrical failures, shorts, or even fires if left unaddressed.

The other choices, while potentially relevant to wire performance, do not directly correlate with overheating in the same manner. For example, worn insulation may be a result of overheating, but it does not specifically indicate the immediate issue of excessive current flow. Similarly, excessive resistance is a condition caused by problems like corrosion or degradation but does not inherently mean that the wire is getting hot. Finally, using an incorrect wire size can lead to overheating due to undersized conductors not being able to handle appropriate current loads, but typically the overheating is identified through the measurement of current flow rather than directly attributing it to wire size.