I got a solarmeter to measure the UVI levels after listening to https://www.chameleonbreeder.com/podcast/ep-91-veiled-chameleon-lighting/
I was Running a 6% in a quad lighting fixture with basking at 7 inches. Lighting on top of enclosure with screen in between. Your levels will be different based on the fixture meaning 1 bulb or 2 or 4. Also what reflector your using. What the light is passing through. If you have a fixture with more then 1 bulb where it is located in your fixture. And what brand of UVB bulb your using.
Anyways when I measured my UVI reading using the solarmeter I was not even at a 1 using the quad fixture with 6% at that distance. You also have to allow for how far up your cham is going to be in relation to your branches. I got a 12% to replace my 6% so that his range of UVI will be between a 3-5 at branch distance of 7 inches accounts for how much higher his body will rise above into the rays.
I have foliage so he can get out of the rays should he want to as well.
I highly recommend ordering a solarmeter. So you can get an exact reading based on what is needed for your Cham and what your are using in your set up. Only base yours off someone else's distance etc if you can mimic it exactly to be sure you are not over exposing to UVB as well.