Steel or Composite? The Transmission Conductor Debate Is Missing the Right Cost Metric

A T&D World analysis published this month argues that utilities are overpaying for composite-core transmission conductors. The case is straightforward: advanced steel-core conductors (ACSS/TW) delivered a 218% capacity increase over conventional ACSR on a reconductoring project at one-third the cost of new line construction. Per-foot pricing backs this up. ACSR Finch runs $2.00 per foot. ACCC Munich runs $5.30.

That comparison is accurate. It is also the wrong metric.

The Right Metric Is Cost Per Amp

Signal. Per-foot, steel wins. Per-amp of delivered capacity, composite wins, and it is not close. ACSR delivers capacity at roughly $47,000 per amp. ACCC delivers it at $25,000. That is a 47% cost reduction per unit of usable capacity.

Context. The difference comes from how much current each conductor can carry at operating temperature. An ACSR Finch conductor maxes out at 1,266 amps at 100 degrees C, and at actual operating conditions sits at 93 degrees with just 66 amps of reserve. An ACCC Munich conductor rates for 2,376 amps at 200 degrees C and operates at 75 degrees with 1,176 amps of reserve. That reserve capacity is what you are paying for when you pay the per-foot premium.

Implication. Build your conductor bid evaluation around cost per amp of delivered capacity, not cost per foot. A procurement team that evaluates conductor bids on per-foot price alone will systematically choose the option that costs more per unit of what they actually need: capacity.

Where Steel Still Wins

This is not a blanket argument for composite. Advanced steel-core conductors have a strong case in specific conditions.

When existing structures are in good condition and can be reused, ACSS/TW reconductoring avoids permitting, right-of-way acquisition, and new foundation costs. Those savings can exceed the capacity premium of composite. Southern California Edison saved customers $85 million using ACCC on their 230 kV project, but that project involved structure replacement that favored composite economics.

For projects where existing hardware supports reuse, the total installed cost advantage of steel-core reconductoring is real and significant.

The Reconductoring Wave Makes This Decision Urgent

The bipartisan REWIRE Act (S. 3947) directs FERC to improve return on equity for reconductoring projects, opens DOE State Energy Program funds for feasibility studies, and establishes regional research collaboratives. ClearPath Action estimates reconductoring could reduce grid costs by $85 billion by 2035.

That legislation will accelerate conductor procurement across both types. Whether you are buying steel-core or composite-core, the volume is increasing. The procurement teams that sort out their evaluation criteria now will be ahead of the wave.

What to Measure in Your Next Conductor Bid

Three metrics that separate informed bids from per-foot-price bids:

1. Cost per amp of delivered capacity. The number that determines what you are actually paying for usable grid capacity. Request rated capacity at operating temperature, not maximum capacity at thermal limit.

2. Total installed project cost. Conductor is less than 20% of total project cost. Structure savings, span length, and foundation requirements drive the rest. A conductor that costs 2.5x per foot but eliminates 30% of structures may cost less installed.

3. 30-year line-loss savings. On a 40-mile, 220 kV project, switching from ACSR to ACCC reduces line losses by 14,512 MWh per year. At $50 per MWh, that is $21.8 million in cumulative savings over the conductor’s life, with break-even in 35 months. At $100 per MWh, break-even is under 18 months.

The right conductor depends on the project. The right evaluation depends on measuring the right thing.