The cage is raised to allow the UTH to "breathe". You don't want it resting right on the table/counter top surface. First, yes, it may overheat - even to the point of causing a fire. Second, the tank would rest right on the power cord and that could cause a short. Most UTHs will come with little rubber "feet" to stick to the corners of your cage, but I find these rubber furniture pads work great - they're a bit larger and therefore more stable.