What is the purpose of shielded electrical wire?

• A. EMI/RFI protection
• B. Weight reduction
• C. Increased heat dissipation
• D. Lower cost

Answer: (A)

Shielding around electrical wiring is meant to block external electromagnetic fields from getting to the conductors and to keep the cable’s own signal from radiating outward. This reduces EMI and RFI, which is vital in aircraft to keep avionics, radios, and sensors free from noise and crosstalk. The shield is usually a metallic layer (like braided copper or foil) that is tied to ground, forming a Faraday shield that steers interference away from the inner conductors. While shielding does add material and weight and can affect heat flow and cost, its primary purpose is to preserve signal integrity by minimizing interference.