The light dimmer goes on the UTH. They heat up to 140 degrees and will cool the snake. You want your UTH to be the Hot Spot 88-91 and the Heat Lamp to be the ambient cool temp 76-81...
For a 10-20G tank a 60 wat CHE (Ceramic Heat Emitter) will make it around 80.
You should run a thermostat for the CHE/Heat Lamp. Here is a Sticky you can follow for Aquariums.
https://ball-pythons.net/forums/show...-With-Pictures!