Abstract: A heating element construction for a mesh mat used in an underfloor heating system. The heating element includes a heater wire having one or more conductors spirally wound around a center strand and an insulating jacket surrounding the conductor. The heater wire is doubled back on itself to provide two counterflow portions which are spirally wrapped around each other. The electric current flows in opposite directions in the two counterflow portions to cancel the electromagnetic field. A braided metal ground shield surrounds the heater wire. A protective outer cover surrounding the ground shield resists abrasion and water.

Abstract: A monitor for use during installation of under floor warming mats to monitor the condition of the electric heating elements. Three lead wires extending from the monitor have alligator clips allowing them to be clipped to the hot, neutral and ground leads of the heating elements. A monitoring circuit generates an audible alarm if the hot or neutral wire is cut or if the ground sheath is electrically connected to either the hot or neutral wire.

Abstract: An electrical heating system thin enough to be installed under finished flooring. A meshwork mat constructed in a leno configuration receives an electric heating element which is threaded through aligned openings in the twisted strands of the warp strands. The strands of the mat and the intersections between the criss-crossing warp and weft strands are coated with a polymeric fusing material. The heating element is arranged in side by side runs to minimize the electromagnetic field effects. Connecting runs between adjacent pairs of side by side runs are arranged linearly end to end. A return wire is extended adjacent to and side by side with the connecting runs.