These are bare stranded conductors for overhead transmission and distribution lines, named for what they are made of. AAC is all hard-drawn aluminium, AAAC uses an aluminium-magnesium-silicon alloy for higher strength, and ACSR surrounds a galvanised steel core with aluminium wires to get the strength needed for long spans. The choice between them is a trade-off between conductivity, tensile strength, weight and corrosion resistance for the span lengths and loadings of the line.
Key applications
- Overhead transmission and distribution lines at all voltages
- Long river, valley and railway crossings requiring high tensile strength
- Rural distribution lines on long pole spans
- Substation busbar connections and jumpers
- Earth wires and overhead earth returns
- Line reconductoring to increase circuit capacity
Features and benefits
- ACSR combines high breaking strength with low weight for long spans
- AAC offers the best conductivity per unit mass where spans are short
- AAAC gives strength close to ACSR with better corrosion resistance and no bimetallic couple
- Concentric lay stranding keeps the conductor flexible enough to handle and tension
- Wide standardised size range simplifies line design and accessory selection
Specification notes and limitations
Bare conductor is live and lethal on contact: the entire safety case rests on clearances, approach distances and effective isolation and earthing, with no margin provided by the conductor itself. Mechanical design governs everything — sag and tension calculations, ice and wind loading, aeolian vibration and the fittings used at suspension and tension points. ACSR mixes aluminium and steel, so joints and fittings must be designed for bimetallic contact and the grease in the core must not be disturbed during jointing. Aluminium conductors creep under long-term tension and must never be kinked, dragged over hard ground or allowed to birdcage during stringing, as a damaged strand becomes a hot spot. Running conductors beyond the design temperature causes permanent loss of tensile strength and increased sag.
