And if you run heat tape under a tank or cage, DO NOT allow the tank/cage to sit on the cord. It might not be the heat tape itself that fails, but the cord.
To avoid this situation, I use rubber weather-stripping on the bottom edges of my tanks, with gaps left both for air & for the cord. The weather-stripping is
readily available in all hardware stores, is sold on rolls (also not expensive), and it's peel & stick -very easy to snip with scissors & install. It also prevents cages
from sliding easily...making things safer, whether or not you live with earthquakes.