When it comes to inductance in circuits, it is a rule of thumb to minimize the loop area. This implies a return path (i.e. two wires). There is also self inductance of a single wire.
I am not sure how they play together: Do I need to add them? Or do I need to choose one, depending on the geometry? If so, which one to pick?
Example: Voltage source to sink, connected by two 1mm diameter wires in parallel (3mm apart) at a distance of 1m (one wire is supply, the other is return/ground).
A calculator for Parallel Wire Inductance tells me the inductance of this configuration is 705nH.
Another calculator for Wire Self Inductance tells me that the inductance (self inductance) of each wire is 1.51uH.
Note that if the two wires are completely adjacent to each other (distance 1mm instead of 3mm), 705nH becomes 0H which makes sense because the loop area is zero. Do we still need to consider self inductance in this case?
What is the correct equivalent circuit? Do I need to consider the first inductance ("loop area") or the second one ("self inductances") or both?