What Steffe said!
I've built 3 now 2 mini and one full size glass front. on the the small wine cooler i used 2 strips of 3".
Mine (the gass station cooler) I used 2 strips of 11" full length. my temps can only reach 92 deg. and hods purfectly at 89.
I used the false back, heat chamber style so none of my heat tape is in the cooler. i've seen 3 and made 2 like this and it is extremly efficiant. i can hold
2 tenths of a degree from top to bottom.
Eric