Surface Area Loading

It is possible to design an element in a variety of sizes all of which would in theory give the desired wattage load or power density dissipated per unit area. However, it is essential that the load on the surface of the element is not too high as the transfer of heat by conduction, convection or radiation from the element may not be rapid enough to prevent it over-heating and failing prematurely.

The suggested surface loading range for the type of appliance and element are shown below – but this may need to be lower for an element working with more frequent operating cycles, or at nearly its maximum operating temperature, or in harsh atmospheres.