adapter between thicker and thinner AWG wires
I use these quite often; https://www.grainger.com/product/4FE28?gclid=Cj0KEQjwk-jGBRCbxoPLld_bp-IBEiQAgJaftemBgg3D7VVxKqJBI4doBh5jCrie0bHhEhx2V9w9Op8aAm9i8P8HAQ&amp;cm_mmc=PPC:GOOGLEPLAA--Electrical--Wire%20Connectors-_-4FE28&amp;AL!2966!3!166588026391!!!g!81032122797!&amp;s_kwcid=AL!2966!3!166588026391!!!g!81032122797!&amp;ef_id=VxBI9gAABZPDSe7V:20170328142529:s

The wire gauge range is 26 to 19 but I have had success with 18 gauge wire.

Another methode wouls be to solder and cover with shrink tubing.