I learned something this morning that I think is worth passing on.. I have a Reptitherm heat control thermometer with a sensor that hangs in the brooder.. I took the ceramic heater out and set it on the counter top.. It had been turned off and was cold to the touch.. I had the Reptitherm turned to the off position.. then I removen the sensor and just let it hang off the countertop.. guess what ?? there is no OFF on that thermometer control.. It is just way low.. so with the sensor hanging in the cool morning air, the light came on, (I didn't notice it) and the ceramic heater was activated.. I did notice the loud POP !!!! and smoke.... now there is a perfect 4 inch diameter black burnt spot on the countertop.. all the way through the formica.. just a word of caution to those of you who might be using one of these Reptitherm 500..