its good to understand the orders...
but when making decisions, based on charts, you have to know and understand the context of the chart and its intended use,
something that may define maximums.. is not necessarily stating use standards or safety protocol..only what that wire might carry for 5 minutes before becoming dangerously hot
Since BFL asked about ampacity----Most of the wire ampacity charts I see on the internet are based on the maximum ampacity that the wire is rated to carry. Distance and voltage drop are covered in other calculators but have naught to do with the current carrying capability of the wire. Mr Wiz has explained the relationships between wire, fusing, and loads much better than I could.