i tape heat tape directly onto the shelves ( i nyears past I didn't even boher to tape, might be why I wore out a couple pieces wore fast cause there was direct rubbing all the time.) I found that liquid nail works really well to hold the tape down andwont aloow i tto roll back up. I then quick glue tiles down ( now ) to act as an bump guard as well as a small spacer > preventing overheat it looks like now. but it does require the tape to run at a longer time cycle . the main think with the heat tape is t omake sure the ends are covered and protected to prevent breakage.