Originally Posted by vgorst
For a 4x2ft viv you need a 3ft UVB. The UV shouldn't go the full length as you need to allow for a photogradient (light and shade) so that the beardy can self-regulate effectively.
Wattage of the basking bulb can vary and you may need to test with a few different watts. For a 4x4ft I would say a 60-75w would be best to start with.
Dimming thermostat wise, habistat or microclimates are good. I'm not sure if you should plug the UVB into the any of the thermostats but have to admit I don't know the ins and outs of the new digi ones. All else fails get a normal dimming stat and a timer.
Go by what this lady has said and fail you shall not! Just to clarify she is correct on uv length and position, you want the 3ft version, not the 4f, for a 4ft viv.
Uv bulbs cannot be dimmed via a thermostat, you would need a dimmable ballast and a few hundred pound to buy one at that! If you still wanted two probes then I'd look at the new range from habistat, otherwise I can't recommend their old range enough and should drop significantly in price now I'd hope. You can then simply plug this in to a household timer for automation.