Heat tape stops water pipes from freezing by providing enough warmth to keep the pipes above 32 degrees Fahrenheit through electrical resistance heating. The heating elements inside some heat tapes provide a constant heat when plugged in, while others include a thermostat to reduce wasted energy.
There are several types of heat tape available, and care should be taken when installing since each behaves in a different way. For instance, the simplest forms of heat tape can overheat if the tape crosses over itself while wrapping around the pipe, potentially starting a fire. The close proximity of electricity and water also increases the risk of injury, so homeowners should follow the installation instructions carefully.