Type 2 elements consist of a resistive oxide layer applied directly to a metal substrate and with the conductive contact applied to the surface of the oxide such that the current flows through the thickness of the oxide from the conductive contact to the conductive substrate. Elements of this type will readily boil water in a kettle. A typical construction would be illustrated by a disc of aluminium 120mm dia, and 5mm thick, onto which is deposited an oxide layer 10Omm dia and onto the surface of this oxide is sprayed a copper contact layer 90mm dia. These work by applying 230 volts to the contact layer and neutral to the aluminium disc and work at 2-3 amps
Type 2 elements offer a potential cost reduction versus Type 1 elements since they do not require any expensive glass ceramic insulating layer as do the so-called ‘thick film’ printed kettle elements.
This Type 2 element configuration is generally more tolerant of the types of substrates on which it can be used. The temperature at which Type 2 elements can be operated depends upon the coefficients of thermal expansion and the melting points of the metal substrates and, for example, using aluminium substrates with a melting point of, say, 750°C, it is possible to produce elements working at 650°C. With copper or mild steel substrates these temperatures can be increased.