Inductive coupling

From Electrical Installation Guide


The disturber and the victim are coupled by a magnetic field. The level of disturbance depends on the current variations (di/dt) and the mutual coupling inductance.

Inductive coupling increases with:

  • The frequency
  • The proximity of the disturber to the victim and the length of the parallel cables,
  • The height of the cables with respect to a ground referencing plane,
  • The load impedance of the disturbing circuit.


(see Fig. R36)

  • Nearby cables subjected to rapid current variations (di/dt)
  • Short-circuits
  • Fault currents
  • Lightning strikes
  • Stator control systems
  • Welding machines
  • Inductors
Fig. R36 – Example of inductive coupling


  • Limit the length of parallel runs of disturbers and victims to the strict minimum
  • Increase the distance between the disturber and the victim
  • For two-wire connections, run the two wires as close together as possible
  • Use multi-core or touching single-core cables, preferably in a triangular layout
  • Position a PEC bonded at both ends and between the disturber and the victim
  • Use symmetrical transmission systems on correctly implemented, symmetrical wiring systems
  • Shield the disturbing cables, the victim cables or both (the shielding must be bonded)
  • Reduce the dv/dt of the disturber by increasing the signal rise time where possible (series-connected resistors or PTC resistors on the disturbing cable, ferrite rings on the disturbing and/or victim cable)