Standard Specification for Concentric-Lay-Stranded Copper-Clad Steel Conductors (CCS) — a fully bimetallic stranded conductor comprising entirely of hard-drawn copper-clad steel wires, delivering copper-grade conductivity and corrosion performance together with the high tensile strength of steel for overhead ground wire, messenger, guy, and ground-grid applications.
ASTM B228 covers bare concentric-lay-stranded conductors composed entirely of hard-drawn copper-clad steel (CCS) wires (per ASTM B227), without any pure-copper or other metallic component. Unlike B229 "Copperweld" composite conductors (which combine solid copper wires with CCS wires), every wire in a B228 conductor is a bimetallic CCS wire, giving the stranded product uniform mechanical, electrical, and corrosion characteristics across its entire cross-section.
The all-copper-clad-steel construction delivers a unique combination of high tensile strength, copper-grade surface conductivity, excellent corrosion resistance, and inherent anti-theft properties. ASTM B228 CCS conductors are widely specified as overhead ground wire (OHGW), messenger wire for self-supporting aerial cable systems, guy strand for pole and tower anchorage, catenary support wire for railway and tram systems, buried ground grid conductors in substations, and as stress-bearing ground returns in telecommunications infrastructure.
B228 CCS is a fully bimetallic concentric-lay-stranded conductor. Every wire is produced from a high-strength steel core onto which oxygen-free copper is metallurgically bonded as a continuous, uniform outer cladding. There is no separate solid-copper wire; the copper cladding on each strand provides conductivity, corrosion protection, and the recognisable copper-coloured surface finish, while the steel core provides the tensile strength.
Each wire is a high-carbon steel core with a continuous, metallurgically bonded outer layer of oxygen-free copper. All wires conform to ASTM B227. The entire conductor cross-section consists of these bimetallic wires — no separate solid-copper strands.
Wires are concentrically stranded with each successive layer having 6 more wires than the previous. Common configurations: 3-wire, 7-wire (1+6), 19-wire (1+6+12), with 37-wire and 61-wire constructions covered in current revisions. Adjacent layer lay directions are opposite.
Grade 40 HS (40% IACS, High Strength) for messenger and ampacity-driven grounding; Grade 30 HS and Grade 30 EHS for long-span OHGW and guy where strength dominates; Grade 40/30 DSA (Dead-Soft Annealed) for flexible buried ground grids.
Joints in individual copper-clad steel wires are governed by ASTM B227 — any joints made before final wire drawing must preserve tensile continuity and cladding integrity. Finished stranded conductors must exhibit the full rated breaking strength corresponding to their grade and construction.
Representative sizes for 7-wire Grade 40 HS (40% IACS, High Strength) CCS per ASTM B228. Rated breaking strength (RBS) reflects the aggregate tensile load of all copper-clad steel wires. DC resistance corrected to 20 °C per ASTM B193. Grade 30 HS and 30 EHS offer approximately 10–25% higher RBS at the same physical size, with correspondingly higher DC resistance.
| Size (AWG) | No. of Wires | Wire Dia. (mm) | OD (mm) | Mass (kg/km) | RBS (kN) | DC Resist. (Ω/km @ 20 °C) |
|---|---|---|---|---|---|---|
| 7 No. 10 AWG | 7 | 2.59 | 7.76 | 306 | 30.7 | 1.181 |
| 7 No. 9 AWG | 7 | 2.91 | 8.72 | 386 | 37.2 | 0.937 |
| 7 No. 8 AWG | 7 | 3.26 | 9.79 | 487 | 45.1 | 0.743 |
| 7 No. 7 AWG | 7 | 3.67 | 11.00 | 614 | 54.7 | 0.589 |
| 7 strand 1/0 | 7 | 3.12 | 9.35 | 444 | 41.2 | 0.813 |
| 7 strand 2/0 | 7 | 3.50 | 10.51 | 560 | 50.0 | 0.645 |
| 19 No. 9 AWG | 19 | 2.91 | 14.54 | 1,049 | 95.8 | 0.348 |
ASTM B228 requires that tests for physical and electrical properties of individual wires be performed before stranding (per ASTM B227), and that the finished stranded conductor meets the following:
ASTM B228 CCS is specified where both high tensile strength and copper-grade surface conductivity are required: overhead ground wire for distribution and transmission lines; messenger wire for self-supporting aerial fibre, coax, and power cables; guy strand for pole and tower anchorages; catenary and contact-wire support for railway and tramway systems; and — especially for the Grade 40/30 DSA (dead-soft annealed) variants — buried copper-equivalent ground grids in substations, telecom huts, and critical infrastructure. Because every wire has a steel core, CCS resists cutting with hand tools and has negligible scrap value, making it the preferred substitute for solid copper grounding in regions where copper theft is a concern. The full copper surface also ensures that the conductor presents copper at every termination, bond, and exothermic weld — making it directly compatible with standard copper grounding hardware and connection methods.
Official Standards & References
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