Some time ago, the code committee addressed the issue of "who decides?"
Ultimately, they settled for language saying a "qualified person" has to make what is very much a judgement call.
Who is a 'qualified person?' The texts in my apprentice program state explicitly that it is NEVER the electricians' responsibility. (I might quibble with that, but that's another discussion). An earlier attempt tried to say "Professional Engineer," but engineer schools simply so not address this topic, nor do most engineers have any experience in the area.
Two areas have plenty of 'qualified' people. First, the ISA, or 'instrumentation society,' certifies the folks who do the control work in the oil and chemical industries; you can be sure these folks have the necessary background. Then, there are the insurance companies (especially Factories' Mutual), whose risk assessment folks know the topic well.
The rest of us .... electricians, inspectors, etc., ... are pretty much out of the loop, unless our specific experience has educated us.
