Planar heating element for underfloor heating

A composite heating element comprising:

• a heating element comprising
• a flat sheet having a first surface and a second surface each of which is defined by an insulating material;
• a first conductor and a second conductor for connection thereacross of an electrical voltage;
• and a conductive material extending between the first and second conductors and located between the first and second surfaces such that the voltage causes a current through the conductive material which generates heat substantially across the full extent of the sheet;
• wherein the heating element comprises:
• a first flexible electrically insulating plastics layer defining the first surface;
• a second flexible electrically insulating plastics layer defining the second surface;
• the layers being connected in overlying relationship to form an elongate sheet with inside surfaces and outside surfaces and overlying side edges;
• the first and second conductors comprising respective ones of two continuous electrodes each running along the element between the layers each along a respective one of the side edges and arranged for connection across a supply of a voltage;
• a first strip of an electrically insulating material applied over the first conductor which defines a first slot between the first strip and the first conductor allowing insertion into the first slot between the first strip and the first conductor of an electrical contact of a first terminal;
• and a second strip of an electrically insulating material over the second conductor defining a second slot between the second strip and the second conductor allowing insertion into the second slot between the second strip and the second conductor of an electrical contact of a second terminal.