For the best performance of your heat cable and radiant roof edge ice dam prevention system, it is a good idea to have the heat cable system  on at temperatures that they will be most effective. This means that they should be on as it approaches freezing. We recommend 35 to 37 degrees so that the systems will turn on as the temperature is dropping. We also recommend turning the heat cables off when it drops below 5-10 degrees. This is because we generally don't see much new snow when it is that cold, snow melt from heat loss and solar gain is not that great, and the heat cable systems have to work really hard when it is that cold. 

This can be done through a switch - where the home or business owner switches the system on and off. But, we also use a thermostat controller to do this automatically. Here is a video which shows how to operate this particular controller. Enjoy.