10 gallon is fine, I used the zoomed one rated for 10-20g tanks, if I could do over I would go down a step but either way a thermostat will control the temps vs just relying on the wattage. (also lots of people have suggested to attach it to a piece of foil instead of the glass directly so that it is easier to maintain and less direct heat that could hurt yoru snake.) And in case of a power outage, your average normal house temp is fine, the snake will never hurt for staying at that temp all the time. (they can be mid 70's all the time, but the area to go for higher temps is for better digesting)