Lighting is another often contentious topic when it comes to keeping snakes, and many keepers dispense with it altogether. People can and will argue all day whether snakes 'need' UV. Many snakes obviously don't 'need' it and can be kept without it and survive. Whether UVB benefits them and whether it SHOULD be provided is a completely different discussion.I will not go into all the reasons for providing it here, but instead limit myself to describing my own set ups. I provide UVB to all my reptiles and strongly advocate this. 

In the case of Diadem snakes, I use Arcadia T5 bulbs along half the terrarium (the same half that includes the heat bulb and mat) set to 14 hours of light in spring and summer, to 10 hours of darkness. During spring and summer periods the lights are switched on at 07.00 and turned off at 21.00. Diadem snakes enjoy basking and are often seen curled up beneath these lights, either cryptically from piles of litter and cover, or - as time passes and they become more secure with the keeper - more overtly out in the open.

While it might be surmised that, since these snakes come from arid environments with high UV Indices, they require a lot of UVB, again I find it better to play it safe. These are crepuscular animals which, although fond of basking in the wild, are more usually found at night, in early evening and early morning. If we are to place them in the famous ‘UV Tool - How much UV does my reptile need’ they would fit Zone 2 - partial sun/ occasional basker. Guidance for such species has maximum UVI at 1.1 to 3.0. So I aim for a UV index no higher than 2.0.