comments:
Really, what I was saying is "I used solid core, and that was a bit of a mistake." But one that I don't entirely regret. Solid core should not be used to connect to the LED strips themselves, as in you should not try to solder solid core to them, or use the push-pin type connectors. Ergo, you either need to use stranded wire throughout, or switch from solid to stranded. Solid core wire is stiffer, so I find it easier to work with when doing long runs, especially if attached, like running alone ceiling or floor joists, etc.. Being stiffer, it needs fewer attachments (staples or whatever), and/or does not need to be stretched tight. If you do direct underground burial, it wouldn't matter. Burial in conduit, it might help in pulling the wire through. With solid core, you would at some point need a junction to go from solid to stranded, even if it's nothing more than a WAGO clip or wire nut.