Over here in England we use thermostats with every reptile we have. So if we want a 200 watt bulb on our chemeleons we can as the thermostat will just turn it off when it reaches desired temps. Do people in the US use thermostats. as I have noticed a few people not being able to get temps right with a 60 watt and too hot with a 100 watt. Why not just use a thermostat?
The problem with that Bradley is that having set your stat at a given temp, lets say 90f, your stat either turns off or regulates to maintain 90f.
So good so far, but you're setting the stat to maintain maximum air temperature.
Maximum air temperature is not the same thing as basking temperature.
Your reptile will need to raise its body temperature by exposing itself to temperatures above the maximum air temperature (basking).
Here comes the problem....
Our reptile must get within a given distance of the heat source in order to do that, regardless its 100watt or 200watt.
Since your lamp or fitting dosent move like the sun, once your reptile is within range enough to heat up above max air temp, the heat its exposed to will depend on the heat produced by the given source.
A 200 watt bulb will be considerably hotter than 100watt.
Since reptiles are notorious for thermal burns due to different skin structure/heat/pain reflexes being unlike ours, the hotter the heat source, the greater the inherent risk of a burn.
Some folk live in colder climates, like yourself, in which case, glass tanks are more common than screen (to hold heat & humidity), this means our cham under a 200watt is going to get very much hotter than one under 100watt.
While I cant say at exactly what temperature a thermal burn will occur, the hotter the bulb, the further away it must be to avoid that, the further away it is, the more heat is lost, since it rises, making using a hotter bulb than ness, uneconomical and risky.
Better then to use a lower wattage bulb, where possible.
Majority of US keepers use screen type enclosures for chameleons which lose that precious heat alot quicker, hence a lower watt bulb at a suitable and practical distance, maintained all day, allows US chams to bask safely without overheating and being forced to retreat to lower area of the cage, where regulating body temperature will be harder still.
Chameleons being arborial, prefer the upper reaches in general, so a 200watt scorcher will be problematic.
Why shoot a spider when a rolled newspaper will do?

Why spend money on a thermostat where its just not ness? With a screen cage and heat dissipating at a constant rate, your thermostat is useless, unless its pulse proportional anyway.
Different reptiles, different climates, different needs.
