First, I hearty amen to Lord Sorril's advice. Follow that and your BP should be fine. If you're trying to create a hotspot on top of a thick layer of bedding using a UTH, that's dangerous. To get the temperature on top of the bedding high enough, the temperature on the bottom will have to be too high. Your snake could burrow to get closer to the heat source and get burned. Use only a very thin layer of substrate, or none at all, over the UTH. This will give your BP access to a safe basking spot.