That's a really interesting chart - what is the source? I'd be curious to know how they rate 18 AWG as that is used a lot in automotive. Also curious they rate 12 and 14 AWG equivalent at 15 and 20 Amp - my reference is typically industrial control ratings (spent some time there) and house wiring (done lots of that) and there 12 AWG is typically 20A and 14 AWG is 15A rated (but these are bundled cable or raceway ratings - not open air).The chart below shows 12AWG is yellow in the chart. voltage drop not to relevant for very short runs. the connection are realy the bad point the don't carry the load even when new.