I only have a few BPs in my house right now and Im looking into buying my first rack (yeah!) Ill be buying it from ReptileBasics and anything else I need. Right now I have a prewired Ranco, Im reading that racks should be hooked up to proportional thermostats with a back up thermostat? Is that right? How exactly does that work? I don't understand how the two can work together or how the physical hook up would look like. What should I be looking for in the proportional thermostat? I know some models are labeled as grounded, what does that mean?