Lead-Coated and Lead-Alloy-Coated Soft Copper Wire for Electrical Purposes

B189: Standard Specification for Lead-Coated and Lead-Alloy-Coated Soft Copper Wire for Electrical Purposes

In the intricate world of electrical engineering, material integrity is paramount. For applications demanding enhanced corrosion resistance and specific electrical properties, the ASTM B189 standard provides an essential framework for specifying lead-coated and lead-alloy-coated soft copper wire. This authoritative specification ensures that professionals have a reliable benchmark for material selection and quality assurance, contributing to the longevity and performance of critical electrical systems.

What is B189?

ASTM B189 is the definitive standard for lead-coated and lead-alloy-coated soft copper wire intended for electrical applications. Originating from ASTM International, this specification establishes comprehensive requirements for the material's composition, physical properties, and dimensional tolerances. Its primary purpose is to guarantee a consistent and high-quality product for use in environments where standard copper might be susceptible to degradation.

Scope & Purpose

This standard governs the production and procurement of round, soft or annealed copper wire that has been coated with commercially pure lead or a lead alloy. It defines acceptable limits for the composition of the coating material, the electrical resistivity of the wire, and the permissible variations in diameter. The specification also outlines requirements for the continuity and finish of the coating, ensuring it is smooth, adherent, and free from defects. It does not, however, cover stranded wire or wire intended for applications other than electrical conduction.

Who Must Comply?

• • Primary audience: Materials engineers, electrical engineers, quality control inspectors, and manufacturing technicians involved in the design, procurement, or production of electrical conductors and equipment.
• • Industries affected: Electrical Equipment Manufacturing, Telecommunications, Power Generation and Transmission, Electronics, and any sector utilizing corrosion-resistant copper wiring.
• • Compliance nature: Typically voluntary, but often mandated by contract specifications, procurement requirements, or by downstream product certifications.
• • Enforcement: Primarily through quality control processes by manufacturers and verification by purchasers or third-party inspection agencies.

Key Requirements Overview

The standard requires that the lead or lead-alloy coating be composed of commercially pure lead or a specified lead alloy, with defined limits on alloying elements. Professionals must ensure the finished wire meets stringent electrical resistivity requirements at 20°C, ensuring efficient current flow. Key provisions include strict tolerances on wire diameter to maintain consistent performance and ensure compatibility with other components. Furthermore, the specification mandates that the coating must be continuous and firmly adherent to the copper substrate, verified through specific immersion tests.

Related Standards & References

ASTM B189 works in conjunction with other ASTM standards to provide a comprehensive material specification. ASTM B193, Test Method for Resistivity of Electrical Conductor Materials, is crucial for verifying the electrical properties of the coated wire. ASTM B258, Specification for Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires Used as Electrical Conductors, provides the framework for wire sizing and dimensional requirements. Additionally, NIST Handbook 100, Copper Wire Tables, offers valuable reference data for electrical conductor calculations.