How To Figure Voltage Drop On A High Power TF

[MEXANDME]

I have an existing 1200W HP transformer (taps up to 22V) on a lighting rearrangement job (reusing the existing lights and transformers but replacing all of the wire) with some really long leads, i.e., one lead is 475 feet with a 140W load.

How does a 140W load tied to a 22V tap effect the overall load on the transformer versus a 140W load tied to a 12V tap?

Is there a way (formula) to calculate various senarios?

Thanks!!!

ROS