Exactly, we did have a dimmer plugged into our thermostat for our corn snake, and it worked fine. I would never trust a repti-temp for 2 heat sources... Ours fluctuated so much. One week it was spot on, and the next it had dipped 10 degrees! We wrestled with it so much, we ditched it and bought a ranco. (i believe) from reptilebasics.com