The short version of the question is: is it safe to have A/C power (120 V) inside an aluminum enclosure? Should I have the ground wire go to the aluminum case? Or should I just make sure that none of the A/C wires touch the case (sounds failure-prone)?
A secondary question: can a black aluminum case be used as a heat sink for a solid state relay?
The long version is this: I'm making a sous vide controller. I'm using an LCD display that normally fits in a PC's disk drive bay (a Crystalfontz drive bay kit), so I bought an aluminum external drive enclosure to hold the project. But A/C power is going into the enclosure, so I'm worried about safety.
The second part is, I started this project using a mechanical relay, but I was worried about its lifetime. (It's rated for a minimum "mechanical life" of 10^6, which is great, but a minimum "electrical life" of 10^5. I don't understand the difference, but 100,000 doesn't sound enough to me, given that a PID algorithm can turn the power off and on a lot and it will be running for hours at a time, and I hope it will work for years to come.)
So I've switched to an SSD. Now I need to worry about heat. Putting a heat sink in this case (a Sabrent EC-ST5B) is going to be tight, if it's possible at all. Could I use the case itself as the heat sink? The aluminum is black. It's cool to the touch, but I don't know how heat-conductive the black coating is.
If an aluminum case is unsafe, or if this case is too small, my plan B is to buy a bigger aluminum or plastic enclosure, use a real heat sink on the SSR, put an electrical junction box inside, ground that box and keep the high voltage stuff inside it. But it won't look as attractive.
Any suggestions?
Thank you,
Bob