Which statement describes the CE-compliant placement of ferrite beads?

• A. On the main power input cable
• B. On the control panel housing
• C. On the data cable coming from the control panel; bead positioned inside the plastic keypad case
• D. On the loudspeaker cable

Answer: (C)

Ferrite beads suppress high-frequency noise on cables, helping the system meet electromagnetic compatibility (CE) requirements. The most effective placement is on the data cable that carries signals from the control panel, with the bead placed inside the plastic keypad case. This locations filters the noise right where the data signal travels, keeping EMI from propagating along the cable to the keypad and ensuring the bead remains enclosed and secure within the device.

Placing a bead on the main power input targets power-line EMI, not the data path, and wouldn’t address the high-frequency noise traveling along the control data line. Mounting it on the control panel housing doesn’t filter the actual cable where the problematic signal travels. Putting the bead on the loudspeaker cable tackles a different cable path that isn’t the primary source of EMI for the control/ keypad interface.