Abstract: Quantum electromagnetic fluctuations induce forces between neutral particles, known as the van der Waals (vdW) and Casimir interactions. These fundamental forces, mediated by virtual photons from the vacuum, play an important role in basic physics and chemistry, and in emerging technologies involving, e.g. micro-electromechanical systems or quantum information processing. Here we show that these interactions can be enhanced by many orders of magnitude upon changing the character of the mediating vacuum-modes. By considering two polarizable particles in the vicinity of any standard electric transmission line, along which photons can propagate in one dimension (1d), we find a much stronger and longer-range interaction than in free-space. This enhancement may have profound implications on many-particle and bulk systems, and impact the quantum technologies mentioned above. The predicted giant vacuum force is estimated to be measurable in a coplanar waveguide line.