Out of curiosity, and to learn something, I want to learn about reasons behind electrical codes (for this purpose, it doesn't matter which ones). Especially since it's often mentioned on the site that there are reasons behind code, ones which we may fail to notice ourselves.
At first I wanted to ask about resources to learn this from, but that would encourage link-only answers and generally bad form. An alternative that comes to mind is to ask a list question, with one rule and reason per answer, if that is allowed.
Or is this simply not a question for this site? Although I do believe such a resource would be valuable.