Abstract: An electric cartridge heater for use as an immersion heater in a steam table tank has a tubular elongate stainless steel sheath with a curved inner surface attached to a riser tube adapted to be connected to a wall of the tank and contains an electric heater element. A copper heat transfer member having an enlarged, curved surface complementary to the inner surface of the sheath is urged into close, intimate thermal contact therewith and transfers heat from the sheath to a bimetal thermostat for turning off the heater element in response to a rise in temperature of the sheath above a predetermined level.