Janek

You cannot. Happens very rarely but sometimes electronics in general can end up in magic smoke or even worse.
 
Best you can do is to look ahead and think about what would happen IF. Are flammable objects close by? Does the device lie on a wooden table? Are other devices close by that radiate heat and cause the concerned devices to heat up additionally?
How is your local public power supply? Do voltage spikes occur often? If so think about installing devices in the building connection that prevents such spikes from hitting your stuff. Kind a lightning conductor but way more sensitive against voltage above rated.
 
Try to look for more general information about fire hazard prevention. Maybe ask your local firefighter station.