I'm trying to figure out the voltage drop across a 2.5mm^2 (14 AWG) cable.
The formula I've used is V_drop = (Length in Meters * Current * 0.017)/(area in mm^2).
For a 14 AWG cable I understand the Ampacity is around 15A. With an example distance of say 1500m, this equates to 153V drop. However, I'm not sure if this is correct as when I try an online calculator as linked here - this answer is correct only for 3 conductors per phase in parallel. So I am unsure if the formula I have is correct or not or it is used for 3-Phase AC calculations only? Also - does the distance I have need to be doubled for the return path as I have seen on some resources?
What I am trying to essentially do is figure out what my limitations would be for sending 48V DC as far as possible, and am starting out with trying to wrap my head around these voltage drop calculation. I understand that increasing my voltage and dropping the current will help significantly here, but I'm not looking to do that if possible.