It is extremely important that you get yourself a thermostat (not a thermometer) if you don’t already, it is definitely the number 1 piece of equipment you need to ensure your dude is safe.
A thermostat constantly checks the temperature of a certain spot and controls the heat source to correct it.
So if your lamp gets too hot, the thermostat will shut the bulb down.
If it gets too cold, the thermostat will turn the bulb on.
Not only will it improve the safety of the animal and keep temps where they should be, it also gives you piece of mind for when you are away from home that your house won’t be on fire when you return.
They can be purchased from any reptile store and even most pet stores and can be found in a variety of types.
There is the “on/off” type that is recommended for UTH/heat mats. This type constantly sends power until it reaches the right temp, then shuts down until it drops below that temp, then turns on again.
There is the “pulse” that is recommended for ceramic heat emitters (not glass). This sends a constant pulse of power, sort of like the on/off type but at a more rapid pace. This makes it unsuitable for bulbs as the constant flickering will not only destroy the bulbs life span, it will irritate both yourself and your snake.
And “dimming”, which rather than turning off when it reaches the right temperature, it lowers the power frequency being output to keep it steady. If your enclosures temps rise, less power is sent to the bulb.
I would really recommend getting UTH if possible, but as @thecrawdfather said, if that’s all you have available right now just do your best to make it work.
This is different as you are keeping your bulb outside of the enclosure, but here’s what can happen when a snake comes in contact with a heat bulbs cage (in this case, that would be the metal meshing on your enclosure) … Burn Injury Progress!