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

B172: Standard Specification for Rope-Lay-Stranded Copper Conductors Having Bunch-Stranded Members, for Electrical Conductors

For engineers and designers working with flexible and specialized electrical applications, ensuring the integrity and performance of copper conductors is paramount. ASTM B172 provides an essential framework for specifying and manufacturing a critical type of stranded conductor, offering a proven pathway to reliable electrical connections in demanding environments.

What is B172?

ASTM B172 is the authoritative standard that defines the requirements for bare rope-lay-stranded copper conductors. These conductors are specifically constructed with bunch-stranded members, suitable for use as electrical conductors. Its primary purpose is to establish clear specifications for material properties, construction, and performance, ensuring consistency and interchangeability in electrical manufacturing.

Scope & Purpose

This industry-leading standard governs the design and manufacturing of specific types of copper conductors. It covers conductors made from round copper wires, which can be either uncoated or coated with tin, lead, or lead alloys, provided the coating maintains similar diameters and densities to uncoated wires. The standard defines classifications for these conductors (Class I, K, and M) based on wire diameter and intended application, such as special apparatus, portable cords, and welding applications. It does not cover insulated conductors or conductors intended for overhead power transmission.

Who Must Comply?

• • Primary audience: Electrical Engineers, Materials Engineers, Wire and Cable Designers, Manufacturing Engineers, and Quality Inspectors involved in the production or specification of copper conductors.
• • Industries affected: Electrical Manufacturing, Power Generation and Distribution, Telecommunications, Automotive, Aerospace, and any sector utilizing flexible or portable electrical cabling.
• • Compliance nature: Voluntary, but often specified as mandatory by purchasers in contracts and project specifications to ensure quality and performance.
• • Enforcement: Typically enforced through contractual agreements and quality control inspections by manufacturers and end-users.

Key Requirements Overview

• • The standard requires that conductors be manufactured from high-quality copper wires, adhering to specific dimensional tolerances.
• • Professionals must ensure that the stranding construction (rope-lay with bunch-stranded members) meets the specified class (I, K, or M) and intended application.
• • Key provisions include detailed tables for conductor cross-sectional area, number of wires, strand construction, and maximum allowable DC resistance at 20°C.
• • Requirements for coated wires stipulate that the coating material must not adversely affect the conductor's electrical properties or flexibility.
• • The standard also addresses requirements for joints in wires and assembled conductors, ensuring they are made using accepted commercial practices.

Related Standards & References

ASTM B172 works in conjunction with several complementary standards to ensure comprehensive conductor specification:

• • ASTM B3 Specification for Soft or Annealed Copper Wire: Provides the base requirements for the copper wire itself.
• • ASTM B193 Test Method for Resistivity of Electrical Conductor Materials: Essential for verifying the electrical conductivity of the copper used.
• • ASTM B354 Terminology Relating to Uninsulated Metallic Electrical Conductors: Offers definitions crucial for understanding the terms used throughout B172 and related standards.