Definition
An electrical cable in which the inner conductor or conductors are surrounded by a grounded metallic braid or foil wrapping. The shield prevents the conductor from radiating electrical noise and protects it from picking up interference from outside electromagnetic fields.
Plain English
A wire wrapped in a thin metal sleeve. The sleeve is connected to ground and acts like a barrier, stopping electrical noise from leaking out of the wire or sneaking into it from nearby equipment.
Context Anchor
Seen in aircraft radio, instrument, antenna, audio, and ignition-related wiring where electrical noise can affect equipment operation.
Derivation
Shield comes from the Old English scield, meaning a protective cover used in battle. Here the metal braid 'shields' the inner wire from electrical attack — stray signals trying to get in, and its own signals trying to get out.
Why Pilots Care
Prevents radio static, navigation errors, and false instrument readings caused by interference from engines, alternators, and other aircraft systems.
Analogy
It is like a metal screen around a signal wire. The screen helps keep outside noise away from the signal inside.
Intuition Check
Do not assume shielded means armored against cuts or crushing. Here, shielded mainly means protected from unwanted electrical or radio noise.
Example Sentence 1
The ignition leads use shielded cable to keep electrical noise from the spark plugs out of the communication radios.
Example Sentence 2
When routing the transponder cable, the mechanic ensured the shielded cable was grounded only at the equipment end.