"My friends told me that as long as the wire is sufficient to handle the voltage going through it, i'm ok."
Wrong. Amperage (current flow) not voltage is what determines the needed wire gauge. Voltage (pressure) determines how thick the wire insulation needs to be, and so is not a concern on the low voltage downstream of your transformer.
If you want to check voltage drop: Get an AC voltmeter. Set output voltage on the tiu. Go to a section of track and connect the voltmeter. It should read the same. Then run a train or 2 into the area of the voltmeter and see what it reads. Difference is your voltage drop. Without the load of a train or 2, the train cannot be run with ANY degree of accuracy---result is meaningless.
I have grades and lighted cars on a 38v16 layout. Any voltage loss magnifies the effect of these, so I use 14-gauge, with a direct connection from the control panel direct to the block.
When the layout was built almost 30 years ago, for a lowest level storage yards with 12 toggled blocks, I used 18-gauge wire (8 conductor cables) hot the hot feed, rather than the 14-gauge I used everywhere else. I figured that down there I'd be holding the transformer handle anyway, so slowdowns were no issue. Then along came DCS and the performance down there was terrible--poor DCS signals and operational issues. I rewired with 14-gauge and no more problems.
This is my layout and I have my own operational standards. I do not say others must use my system.
