Hi,
In regards to safety, ingress protection is about 46 (low water protection, and moderate hazard protection). The only way your going to have one ‘burn up’ is if you exceed the amperage of 10amps. Even then you have to exceed the 10 amps by another 10 amps for it it melt. The PVC doesnt exactly catch alight but melts and destroys the board. Here is a youtube video outlining what happens hen you exceed the 10amp rating.
If your worried about safety, get yourself a electrical power box and some cable glands similar to this. This is a project I use to demo the switch. With the lid on it becomes sealed and water proof. I personally would never leave the sonoff switch ‘as is’ on a wall or somewhere fingers can touch it. Your relying on a small clip to hold live wires together. At least with the glands you can almost hang from it without it breaking.
