Choose the hanger spacing you need. This does not change the electrical sizing; it is used to show compatible mounting hardware with your cable results.
Measure from the source to the load (one-way). Longer runs increase resistance and may require larger cables to meet voltage drop and ampacity.
How much total voltage you can lose over the out-and-back run. Smaller allowable drop forces larger cable; a larger drop may allow a smaller cable.
The expected maximum current your load draws. Higher current requires larger cables or multiple parallel runs to meet ampacity.
The current used for the voltage drop check. Often set to about 80% of max load (we auto-fill when you change Max Load Current). Higher values demand larger cable to keep voltage drop within the limit.
