Low-voltage and low flux density heating system

A low-voltage heating system for heating a surface area, said system comprising at least one cable having six conductive heating wires contained in an insulated sheath, said six conductive heating wires of said cable being arranged in an upper row of three wires and a lower row of three wires within said cable which is of substantially rectangular cross-section, said upper and lower rows lyina parallel to one another and to a horizontal axis of said cable, said rows being in vertical juxtaposition and separated by a distance h, wherein h is the perpendicular distance between said parallel upper and lower rows, an adequate low voltage supply source, feeder conductor means connected to said supply source, said heating wires being connected at one end to said feeder conductor means, said wires having low resistivity similar to that of copper, said at least one cable and said wires therein being permanently fixed relative to said surface area to be heated;

• said cable having a length (L) based on specific parameters of said system including (i) the operating voltage (E) of said supply source, (ii) the number of phases of said supply sources (iii) the total cross sectional dimension (A) of said six heating wires, (iv) the resistivity (p) of the wire material, (v) the desired thermal power per unit length (P.sub.C) of said cable, and (vi) the connection of said wires in said cable to said feeder conductor means, whereby the resultant magnetic flux density of said cable is less than a specific value at a specific distance from a cable when current is applied to said heating wires in said cable.