Originally Posted by Nathanael
Thank you for your concerns. I feel pretty comfortable with my precautions. All electric is run through a built in GIF breaker and the lights are sealed and wet rated. I've also had a certified electrician sign off.
Any thoughts on the mold?
I assume you mean a "GFCI breaker".
More on the safety: now I see a bead of silicone around the base of each lamp. What I don't see is any sort of water seal on the internal conduit of that fixture, inside of which is likely a wire-nutted pigtail leading to each lamp. That connection, too, will degrade from water (and mold?) exposure. The plastic sheath on much interior-rated electrical cable is susceptible to degradation and penetration by moisture, as well, although some (THWN, which I would expect to find in an exterior light fixture) is not. I suspect, perhaps, that an electrician may not have the foggiest idea exactly what conditions inside a terrarium are like.
I've replaced a few faulty GFCI outlets in my life, which is a few chances I would've had to be exposed to electric shock had I not noticed they weren't functioning properly. They're like seatbelts: often useful, but not so useful that a person should take unnecessary risks.
On mold: I don't purposefully grow moss, but I understand it likes to be really wet, and not too well ventilated. I do grow some orchids, and they mostly appreciate a break from water on a daily-ish basis, and mostly like a lot of fresh air. Mold will grow anywhere there is water, like in your terrarium, and some organic film, which is everywhere. In frog vivs, there's often a bloom of mold, and then it runs its course and declines or the cleanup crew brings it into balance. Sometimes it crops up from time to time.