[Baz]

Sorry Rocketman.....I can't figure out what's happening from your photo and comments.

Are you saying the cable that is getting hot is buried? If so, I would just lay a new one if possible and abandon the old one.

Before you do that, lay a cable along the ground and connect everything just to test it out. If it works OK proceed to bury.

Of course, make sure you buy the correct size and type of cable.

12 gauge is the thick stuff for longer runs and more lights. Most LED system don't need anything that heavy but other than cost it doesn't hurt to use it.

You can also use 14 gauge and then down to 16 gauge and that's it.

I actually use a lot of just 16 gauge here and it works just fine.

I use wire nuts filled all the way up with dielectric grease and have never had a problem and it's a lot swampier here than where you are. Just make sure the wire nut isn't too small, you twist the wires together good, and the wire nut is completely filled up with the grease.

Your crimping system could also work but that's just not how I do mine, FWIW....