as long as the element is enclosed, whats the difference between it and the oil filled besides using twice as much current. and if its electric, there got to be an element somewhere, even in the oil filled.
and the smoke detector I would not hear. no point.
and the heater im thinking of has thermo-protection (personally i think every heater should but seems some don't i guess), works like the thermo-protection in your circuit breakers, unless a copper wire crawls up and bypasses it, it will never get hot enough to burn anything