If I'm reading the chart correctly, in HO. Using 22 or even 24 or 26 awg is good up to 3' in length. I might ask: When is a feeder longer than 3'? So why do so many people use 20 or even 18? Soldering 22 to rail is far easier than 18. And easier to hide. And isn't telephone cable 22 awg? Just ask your friendly phone company tech if he has some extra that would normally be thrown away.
As for solid wire or not, I find it best to use new or not too old wire. That usually helps with any wire. Copper being a necessity, so the newer the better for being able to work with, to solder to, etc.
Morgan Bilbo, DCC since 8/18. Model PRR 1952.
