Electromagnetic Interference (EMI)

EMI, Electromagnetic Interference, is electrical noise induced in cabling by the presence of nearby electrical equipment such as motors, air conditioners, fluorescent lights, and power lines.

What is EMI (Electromagnetic Interference)?

Electrical noise induced in cabling by the presence of nearby electrical equipment such as motors, air conditioners, fluorescent lights, and power lines. Electromagnetic interference (EMI) can interfere with the transmission of signals.

EMI is only a problem with copper cabling. It’s caused when the changing electromagnetic fields generated by one cable induce extraneous currents or interference in adjacent or nearby cables. EMI in copper cabling can be reduced to acceptable levels by

  • Avoiding bunching of unshielded cabling
  • Keeping all cabling away from power cords and transformers
  • Using shielded twisted-pair (STP) cabling instead of unshielded twisted-pair (UTP) cabling
  • Enclosing cabling in external mesh or wire shielding
  • Properly grounding electrical equipment and external shielding
  • Taking care not to excessively untwist the terminating ends of twisted-pair cabling

Electromagnetic Interference examples

EMI can be a greater concern in heavy industrial settings where high voltages and equipment, such as motors and generators, produce high levels of electrical noise. Using coaxial cabling in these settings affords greater resistance to the effects of EMI than using twisted-pair cabling. Fiber-optic cabling is an even better solution in heavy industrial settings because it is wholly resistant to EMI. (Changing electromagnetic fields have no effect on the light waves traveling along a glass fiber.)