The electrical conductor of a heater located inside an electrical distribution equipment has 2.52 mm diameter. The electrical resistivity is 0.8 x 10-3 Ohm.mm. A piece of plastic 1 mm thick with and thermal conductivity is 0.1 W/(m.K) covers long cylindrical connector for electrical insulation purposes. A fan is ventilating the heater and the wind speed is 4 miles/h. The measured current through this heater is 26 A. The average temperature of the component is 68.52 C whilst the ambient temperature is 39C. The maximum current rating of this heater is 30 A. Determine the maximum differential temperature under full load conditions and hence what action should be taken in the following cases:

The fan is switched off

The fan is switched on