Good question. My layout is strictly 1950s Lionel O Gauge 3-rail tubular track with 1950s accessories, lockons, O22 remote switches, etc. I read from several sources (including, I think, here on this Forum) that it is easier and advisable to use solid wire--20 or 22 gauge--to attach to the many terminals on these accessories and devices, and consequently solid wire is recommended in these instances.
I already determined the Wago 221 connector is approved for both stranded and solid wire. So I thought this would be appropriate if and when I need to connect the solid wire to the 14 gauge stranded wire that I will be using to power to the bus.
It sounds like I am now advised to avoid altogether the use of solid wire and instead use stranded wire throughout.
I'm simply trying to get off on the right foot from the start. I hope to avoid using wire that I later discover was wrong or inappropriate (or difficult to use) and then have to re-wire.