ntsqd
technerd
I'm just a Mech playing at being a Elect. but if you're using NEC charts for vehicular low voltage DC you're being led astray. Those charts are intended for AC and generally a given size wire can carry more AC amps than DC amps because unlike DC the AC watts are never fixed and rarely at max. The wires get some chance to cool during the low voltage portion of the AC cycle when little to no current is flowing. Can have 10 Brazillion amps capacity, but if there's no voltage then the amps don't flow. There is a de-rating done in some (all?) of the NEC charts considering that most AC is in some sort of conduit that will inhibit wire cooling. Which is why the NEC specifies only so many of each wire size in a given size conduit. The whole thing is designed to make it so that the electrician in the field doesn't have to do math and can still assemble a safe electrical system that is Code Compliant regardless of the length of the circuit. That was how the whole NEC thing was explained to me ~20 years ago by a CA Licensed Electrician anyway. Memory has likely warped some of that.
I use the Anco Marine chart and formula because those are made for vehicular low voltage DC ("Low Voltage" being under 50 VDC), specifically for boats since that is Ancor's target market. Resources - https://ancorproducts.com/en/Resources I tend to only use the 3% Voltage Drop chart as a fair amount of what I'm working on is either voltage sensitive or performs better with higher voltage.
I use the Anco Marine chart and formula because those are made for vehicular low voltage DC ("Low Voltage" being under 50 VDC), specifically for boats since that is Ancor's target market. Resources - https://ancorproducts.com/en/Resources I tend to only use the 3% Voltage Drop chart as a fair amount of what I'm working on is either voltage sensitive or performs better with higher voltage.