Parallel earthing conductors are very useful to reduce the coupling between cabling and their environment. The behavior of magnetic parallel earthing conductors is more complicated, but very important since most cable management systems are made from steel. This chapter discusses ferromagnetic tubular structures, ferromagnetic cable management systems and related nonlinear effects in case of short circuit and lightning currents. Actually in cable ladders the rods add little to the protection of the cables and the sides can be considered parallel plates. Best protection is obtained when a cable is mounted close to one of the frame sides. Conventional lightning protection measures focus on the reduction of the fire hazard and are insufficient for broadband protection of micro-electronics. Magnetic field lines tend to follow the contours of the magnetic material; therefore, the behavior for open cable trays will be worse compared to similarly shaped trays from nonmagnetic materials.