ASTM CLASS “A"

ASTM Class “A” defines the highest performance tier for bare copper conductors, establishing superior electrical, mechanical, and material requirements for critical applications. Governed by ASTM B3 (Solid Wire), B8 (Stranded), and B33 (Tinned Conductors), this classification ensures uncompromised reliability in extreme operating environments.

Technical Specifications

• Conductor Types:
  • Solid round wires (Ø 0.5–10 mm)
  • Concentric-lay-stranded (7–61 wires)
  • Tinned constructions
• Material Standard:
  • Electrolytic Tough Pitch (ETP) Copper
  • Minimum copper content: 99.95%
• Fabrication Protocol: Physical/electrical tests mandated before stranding or forming

Core Requirements

• Material Purity:
  • Oxygen content: ≤50 ppm
  • Trace elements: ≤30 ppm total (S, Se, Te)
• Electrical Performance:
  • Conductivity: ≥101% IACS at 20°C
  • DC resistance tolerance: ±0.5%
• Mechanical Integrity:
  • Tensile strength:
    • Solid: ≥350 MPa (hard drawn) / ≥200 MPa (annealed)
    • Stranded: ≥300 MPa
  • Bend test: Zero fractures after 180° wrap (4x wire Ø mandrel)

Where It’s Used

• Aerospace: Flight-critical avionics wiring
• Medical: MRI superconducting coils, implantable devices
• Energy: Nuclear reactor control rods, fusion research
• Transportation: High-speed rail overhead lines
• High-Physics: Particle accelerator components