Rope-Lay-Stranded Copper Conductors Having Concentric-Stranded Members, for Electrical Conductors

B173: Standard Specification for Rope-Lay-Stranded Copper Conductors Having Concentric-Stranded Members, for Electrical Conductors

When designing electrical systems and apparatus that demand superior flexibility and robust construction, engineers and manufacturers turn to industry-leading standards for guidance. ASTM B173 provides an essential framework for specifying and producing advanced copper conductors crucial for a wide range of demanding applications.

What is B173?

ASTM B173 is an authoritative standard that establishes the requirements for bare rope-lay-stranded copper conductors. These conductors are characterized by their concentric-stranded members, manufactured from round copper wires that can be either uncoated or coated with tin, lead, or lead alloys. The primary purpose of this specification is to ensure the consistent quality, performance, and suitability of these specialized conductors for electrical applications where flexibility is paramount.

Scope & Purpose

This comprehensive standard governs the construction, materials, and testing of rope-lay-stranded copper conductors with concentric-stranded members. It specifically covers conductors made from bare copper wires, which may be coated for enhanced durability and solderability, intended for use as electrical conductors. The scope includes provisions for conductor classification based on flexibility (Class G and Class H) and outlines requirements for lay length and conductor construction. It does not cover insulated conductors or those intended for overhead power transmission.

Who Must Comply?

• • Primary audience: Electrical Engineers, Materials Engineers, Wire and Cable Manufacturers, Quality Inspectors, and Electrical Designers involved in the specification and production of flexible electrical conductors.
• • Industries affected: Electrical Manufacturing, Wire and Cable, Power Distribution, Electronics, and any sector utilizing flexible cord or apparatus wiring.
• • Compliance nature: While ASTM standards are generally voluntary, compliance with B173 is often specified in procurement contracts, project specifications, and regulatory requirements, making it effectively mandatory for targeted applications.
• • Enforcement: Compliance is typically verified by manufacturers through internal quality control processes, third-party testing laboratories, and customer audits.

Key Requirements Overview

• • The standard requires conductors to be constructed from round copper wires, either bare or coated with specified materials.
• • Professionals must ensure that coated wires possess diameters and densities comparable to uncoated wires to maintain consistent electrical properties.
• • Key provisions detail the classification of conductors into different classes (G and H) based on their construction and flexibility, catering to varying application needs.
• • The specification mandates specific ranges for the length of lay of both the outer layer and the individual wires within stranded members to achieve desired flexibility.
• • B173 outlines acceptable testing procedures and performance criteria for electrical and physical properties, including provisions for elongation tests on wires removed from the completed conductor.

Related Standards & References

ASTM B173 works in conjunction with several other essential standards to provide a complete specification for copper conductors:

• • ASTM B3 (Specification for Soft or Annealed Copper Wire): Provides the foundational requirements for the raw copper wire material used in B173 conductors.
• • ASTM B8 (Specification for Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard, or Soft): While B173 focuses on rope-lay constructions, B8 covers standard concentric-lay constructions, offering a comparative reference for conductor types.
• • **ASTM B193 (