I'm still testing my code. I'm discovering that I haven't implemented the alarms for the light correctly, so it never turns off/on properly...
I have installed a small 12V Fan , cutting a hole for it out of the top of the container. I also drilled a corresponding ammount of inlet vent holes at the opposite end of the enclosure.
So long as the lamp is on, the enclosure will always remain fairly warm, and the fan will run intermittently. I've found it take 15-30 seconds for the fan to cool the enclosure from 25C back to 24C. It may take less, eventually I'm going to put a very sensitive temperature sensor at the fan outlet to ensure it shuts off when the exhaust temperature is the at the bottom of the set point.
About saftey: I've set the fault temperature in my code to be 30C. In my experience most wire insulation is good to about 60C. Additionally, the relay is rated for 240VAC at 25A (That's 6000W), and I'm using 120VAC at <=5A (600W.)