It can be unsafe to have an ASIC running at your home 24/7, because some component might overheat, short-circuit and start a fire while you are sleeping or away from home.
Are you for real? I'm asking because this reads like a joke. Your TV, fridge, AC unit, computer can also overheat and short. What about wood or gas furnaces that most of us have? What about solar panels?
That's why you follow safety rules. For instance, you can put miners in a dedicated room, where there's no furniture around them and nothing to catch fire. You also makes sure there's a smoke detector in that room and that you have a fire extinguisher in the house.
The miners mentioned by OP are submerged, so there's low risk of fire, unless you somehow reach the temperatures where mineral oil or whatever fluid they have in there ignites, but that's well above boiling temperature so a mining unit would need to keep heating up the coolant in the tank until the whole thing starts boiling and then beyond that, to the level of ignition, so something above 150C. They'd get alarms all over the place well before that.
