Abstract: The present invention relates to a thermal line (1) for transmitting an electrical signal to a module block (5) comprising a group of connections for electrical contact to be made by the thermal line (1), and to a system of module blocks. The thermal line (1) comprises a first core (2a) and a second core (3a), a first core insulation material (2b) and a second core insulation material (3b) and also an external insulation material (4), wherein the first core (2a) is sheathed at least once by the first core insulation material (2b) and forms a first line element (2), and the second core (3a) is sheathed at least once by the second core insulation material (3b) and/or is separately sheathed at least once by the external insulation material (4) and forms a second line element (3). Furthermore, the first line element (2) has a first outside diameter (D1) and the second line element (3) has a second outside diameter (D2), wherein the first outside diameter (D1) differs from the second outside diameter (D2).