external conductor and the heating conductor 3 as internal conductor form according to the configuration of fig2 an arrangement of the type of a shielded conductor for instance a co axial cable with the internal conductor as cable core and the external conductor as external cover the heating conductor 3 can thereby at present simultaneously be formed and provided serving as reference potential element which for instance instead of the vehicle floor often provided herefore form define a reference potential for capacity determination the heating conductor 3 and the first conductor 1 are spaced apart from each other such that any line g as indicated by dashed line in fig2 which extends in the cross sectional plane of the sensor assembly which intersects the first conductor 1 and the heating conductor 3 can be brought independent on the spatial orientation of the line g in cross sectional plane by parallel displacement in the cross sectional plane into a position in which it forms a curve secant s of the first conductor 1 thus connects two points of the first conductor 1 being spaced apart from each other in the cross sectional plane to each other without intersecting the heating conductor 3 the heating conductor 3 is surrounded by an insulator or dielectric 4 which extends between the heating conductor 3 as internal conductor and the first conductor 1 as external conductor and is being surrounded in the embodiment towards the external first conductor 1 by a moisture tight protective cover 5 b the heating conductor 3 serves for producing heat by energizing with electrical current such that through this for instance the seat area of a seat cushion can be heated the material of the dielectric 4 is selected thereby such that.