There is a real need to "learn" before you start "inventing."
Sure, a lot of things are not spelled out, are inferred, or considered so common as to not require eleboration. To top it all off, language is not perfect- but it's all we've got!
A reference to a "steel building frame" is generally considered to be a reference to a sort of construction where I-beams and such make up the primary construction of a building .... and not a reference to every incidental piece of steel that might be present.
This reference is NOT generally applie to steel roofing, or aluminum siding, or - as in the pic- an incidental load beam. We're talking houses here, not swimming pools.
There is even some room for debate as to whether the requirement would apply to those light-steel buildings, commonly used for commercial construction.
IMO, one of the prime consideration is that the beams in a traditional steel beam structure may be used for the grounding of transformers, or other power sources.
"May become energised" is another such statement. Sure, anything, anywhere, can, under the right conditions, become energised. Even an empty soda can afloat in the ocean.
So, we need to look at 'where will the electricity come from.' A wire running alongside is generally not considered a source of risk. Change that to a steel junction box, and the answer likely will change. Make it a metal box with both connections and loads - say, a water heater- and the answer is a definite "bond it!"
Another issue we can't escape: code aside, it simply is not possible to be an electrician without making countless 'judgement calls.' That's what a journeyman is paid to do. We're not just a bunch of trained apes, following a cookbook recipe. You can't become an electrician by reading a book, attending seminars, or simply "being logical." You also have to be in the field, doing the work. There are countless differing situations out there, a multitude of construction types. In short, you have to "learn the trade."
