Copper-Clad Aluminum Wire

B566: Standard Specification for Copper-Clad Aluminum Wire

For engineers and designers working with electrical conductors, understanding material specifications is paramount to ensuring the reliability and performance of their systems. ASTM B566, the Standard Specification for Copper-Clad Aluminum Wire, provides an essential framework for the procurement and manufacturing of this versatile conductor material, offering a proven balance of conductivity, strength, and cost-effectiveness.

What is B566?

ASTM B566 is an authoritative industry standard that defines the requirements for bare, round copper-clad aluminum wire intended for electrical applications. Developed by ASTM International, this standard establishes the material composition, mechanical properties, and dimensional tolerances necessary to ensure consistent quality and performance of copper-clad aluminum conductors. Its primary purpose is to serve as a comprehensive technical reference for manufacturers and users alike.

Scope & Purpose

This essential standard governs the production and quality control of copper-clad aluminum wire. It specifically details four distinct classes of wire, differentiated by their nominal copper volume percentage (10% or 15%) and temper (annealed or hard-drawn). The specification outlines critical material properties such as tensile strength, elongation, resistivity, and the physical integrity of the copper cladding. It does not, however, cover insulated wires, cables, or applications outside of bare electrical conductors.

Who Must Comply?

• • Primary audience: Materials Engineers, Electrical Engineers, Quality Control Inspectors, and Manufacturing Technicians involved in the specification, production, or testing of electrical conductors.
• • Industries affected: Electrical Manufacturing, Aerospace, Telecommunications, Cable Manufacturing, and any sector utilizing lightweight, conductive materials.
• • Compliance nature: Generally voluntary, but often becomes mandatory through contractual agreements, project specifications, or regulatory requirements.
• • Enforcement: Primarily through quality control processes within manufacturing facilities and by end-users during material acceptance testing.

Key Requirements Overview

The ASTM B566 standard mandates several key requirements to ensure the quality of copper-clad aluminum wire:

• • The standard requires a continuous, well-bonded copper cladding over an aluminum core, ensuring the integrity of the composite structure.
• • Professionals must ensure the wire meets specified tensile strength and elongation properties, which vary based on the wire's diameter and temper.
• • Key provisions include strict limits on electrical resistivity at 20°C to ensure adequate conductivity.
• • The standard dictates that the wire must be free from defects such as seams, splits, or cladding delamination, verified through specific testing procedures.
• • It also specifies minimum copper thickness and acceptable volume percentages for each class of wire, ensuring the intended electrical and mechanical performance.

Related Standards & References

To fully implement the requirements of B566, engineers often refer to complementary ASTM standards. ASTM B193, Test Method for Resistivity of Electrical Conductor Materials, provides the standardized method for measuring electrical resistivity. Additionally, ASTM B258, Specification for Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires Used as Electrical Conductors, is referenced for standard wire sizing, ensuring interoperability and correct material selection. These standards work in concert to provide a comprehensive approach to copper-clad aluminum wire specification and application.