A practical case from our laboratories: an inflammable heater

A low cost 2kW electric space heater is involved in several domestic fires. As it transpired that the product was tipped-over when it caught fire our laboratories proceeded with the analysis of the product.

From a design point of view, and to comply with the applicable legislation, the appliance must be equipped with a tip-over safety switch that automatically shuts the unit off if it is tipped over. The product was certified by a Chinese organization.

The analysis of the product shows that the heater is not equipped with a tip-over safety switch but with a simple thermostat that shuts off the unit if it overheats beyond a preset threshold. We then proceeded with a functional analysis to determine the temperatures reached by every part of the heater in all positions and in all using circumstances, accidental or not. We then simulated a scenario in which the flow of hot air of the appliance is obstructed by a fabric or floor pvc tile. The results revealed that the only thermal security would trigger in some cases but:

  • The delay is excessive
  • It could not be triggered at all
  • Some internal parts of the product reach temperatures above 150°C
  • It does not prevent fibers to be sucked in and then set on fire when the appliance is tipped over

During our test, we easily caused the appliance to catch fire by simply tipping it over flooring covered with hairs, as frequently encountered in bathrooms. The appliance design therefore appears to be faulty and dangerous.