Heating cable

A cable (1), comprising:

• a first wire-shaped metal conductor (2),
• a second metal conductor (4) extending a predetermined distance away from and parallel to the first conductor (2),
• a matrix (3) made of a PTC material extending along the conductors (2, 4), touching the latter and connecting them to one another electrically, with temperature-dependent electrical resistance and a positive temperature coefficient and
• at least one electrically insulating outer insulation layer (8) surrounding the conductors (2, 4) and the matrix annularly,
• wherein at least a third and a fourth metal conductor (4) are provided which extend a predetermined distance away from and parallel to the first conductor (2), touch the matrix (3) and are connected electrically by means of the latter to the first conductor (2), the second, the third and the fourth conductor (4) being made in a wire shape and, considering the cross-section of the cable (1), being arranged distributed evenly over a circular track surrounding the first conductor (2);
• wherein
• the first conductor (2) is fully embedded into the matrix (3), and the other conductors (4) touch the matrix (3) on its outer periphery and are coated with a covering layer (5) which is made separately from the matrix (3) and is integrally connected to the latter;
• and
• the covering layer (5) is integrally connected to the matrix (3) by crosslinking to form a matrix layer (9) having at least two sections with different electrical conductivity to temperature ratios.