Definition
Copper wire that has been drawn through successively smaller dies without being annealed afterward, leaving it in a work-hardened condition. The drawing process increases its tensile strength and stiffness but reduces its flexibility, making it suitable for applications where the wire must hold its shape and resist stretching, such as overhead transmission lines and certain antenna installations. It is not used where repeated bending or vibration is expected.
Plain English
Copper wire that has been pulled through shrinking holes to make it thinner, which also makes it stiffer and stronger but more brittle. It holds its shape well but doesn't like being bent back and forth.
Context Anchor
Seen in aircraft electrical and maintenance discussions when wire material, strength, and flexibility matter.
Derivation
"Drawn" comes from the metalworking process of pulling (drawing) wire through a die to reduce its diameter. "Hard-drawn" simply means the wire has been left in the hardened state produced by that drawing — it has not been softened by annealing afterward. Knowing this explains both the name and why the wire behaves the way it does.
Why Pilots Care
Aircraft wiring must endure constant vibration and flexing; using hard-drawn wire in critical runs reduces the chance of fatigue failure and electrical interruptions.
Intuition Check
“Drawn” does not mean sketched or marked here. It means the copper was pulled through a forming tool to make it into wire.
Example Sentence 1
The long-wire HF antenna was strung from hard-drawn copper wire so it would stay taut without stretching.
Example Sentence 2
Maintenance instructions called for hard-drawn copper wire in the main bus connections to prevent stretching during flight loads.