Which of the following is a characteristic of aluminum bus work in substations?

The characteristic of aluminum bus work in substations being highly resistant to corrosion in specific environments is significant because aluminum naturally forms a thin oxide layer when exposed to air, which helps protect it from further oxidation. This property makes aluminum a suitable choice for various applications, including substation bus work, particularly in environments where corrosion might be a concern, such as coastal areas or industrial settings with corrosive elements in the atmosphere.

In contrast, while the other options may have some merit in specific contexts, they do not accurately reflect the general advantages associated with aluminum bus work. For example, although cleaning before terminal attachment may not be strictly necessary, it is often recommended to ensure good electrical contact and reduce resistance. Aluminum can also perform relatively well in moisture, but it is not immune to corrosion under severe moisture conditions compared to other materials. The use of varied filler metal compositions is more relevant to welding techniques than to the inherent characteristics of aluminum bus itself.