In my current tank, I use a reptisun 10.0 T5 HO UVB, however, it is sitting on the outside of the tank over the screen top. I'm working on a getting a new enclosure where the UVB will be mounted inside the enclosure, and was wondering if I should still use the same bulb or if it would be too "strong" to be in the inside? Also, how far should the bearded dragon's basking spot be from the light... like how close can the lizard get to the UVB and still be receiving a safe amount?
The screen just blocks some of the UV, it doesn't make it uneffective. You can compensate for a bulb on the screen by making sure the dragon can get slightly closer to the bulb than it would need to be if no screen were present.
For a t5 bulb, you want your dragon to be able to get around 12 inches away from it assuming the bulb is in a fixture with a reflector and no screen blocking it.
Since a screen can block up to 30%, you compensate for that reduction by allowing your dragon to get around 8 or so inches away.
That allows the dragon to get the same UVI exposure as it would at 12 inches or so without a screen.
Whether or not you should continue to use your T5 inside your new tank all depends on the distance. If the distance from the bulb to basking site is around 12 inches, then you can use it inside. If you can't get that kind of distance, then the t5 might not be the best choice for your setup.