ASTM B399 covers concentric-lay-stranded conductors made from round aluminum-alloy 6201-T81 wires for electrical applications. Conductors feature a central core surrounded by one or more layers of helically laid wires. They are classified as:
Class AA: Bare conductors typically used in overhead lines.
Class A: Conductors intended for covering with weather-resistant materials.
Conductor Construction:
Central core with concentric helical wire layers.
Electrical Performance:
Maximum DC resistance per unit length ≤ nominal value.
Critical Dimensions:
Sized to match ACSR conductor diameters.
Material Composition:
Aluminum-alloy 6201-T81 (solution heat-treated, cold-worked, artificially aged).
Designation Standards:
Alloy and temper designations conform to ANSI H35.1/H35.1[M] and UNS A96201 (Practice E527).
Material Integrity:
Aluminum-alloy wires must undergo artificial aging for hardening.
Construction Rules:
Minimum joint spacing between wire layers.
Dimensional Compliance:
Diameters must correspond to standard ACSR sizes.
Unit Systems:
SI units govern density, resistivity, and temperature (mandatory).
Inch-pound or SI units accepted for other properties (mutually exclusive systems).
Enhanced Durability:
Artificially aged alloy (6201-T81) ensures long-term mechanical reliability.
Environmental Resistance:
Weather-resistant compatibility (Class A) suits harsh operating conditions.
Electrical Consistency:
Strict DC resistance limits guarantee conductivity stability.
International Compliance:
Developed per WTO/TBT Committee standardization principles.
Overhead Power Lines (Class AA):
High-voltage transmission/distribution networks.
Covered Conductors (Class A):
Weather-exposed applications requiring insulation (XLPE/cladding).
Coastal, industrial, or high-UV environments.
Critical Infrastructure:
River crossings, wind/solar farms, and grid retrofits.
