For half a century, Copper-Clad Aluminum (CCA) conductors have served the electrical industry with a strong record of safety and reliability. Now, with new independent testing from Exponent, one of the nation’s most respected engineering and materials science consultancies, the evidence is clearer than ever: CCA performs like copper, not aluminum.

CCA performs like copper, not aluminum

Exponent’s exhaustive study of copper, aluminum, and CCA conductors found that CCA matches copper’s electrical stability and outperforms aluminum in every key measure of splice and connection integrity. These results have since informed proposed updates to UL486A-B and UL486C standards, which formally recognize CCA’s distinct performance characteristics. Together with planned revisions to the 2026 National Electrical Code (NEC), this represents a major step forward in aligning the standards with the science — and in validating CCA’s reliability in the field.¹

A Standards System Catching Up to the Science

For decades, UL486C — the standard governing splicing wire connectors — grouped Copper-Clad Aluminum with single-metal aluminum. That outdated classification held CCA to aluminum’s more stringent derating requirements, despite the fact that CCA’s copper surface eliminates the oxide-layer issues that cause instability in aluminum terminations.²

CCA’s real-world record has shown for years that it performs consistently in copper-rated connectors, but the standards had yet to reflect that reality. Exponent’s independent testing provided the data needed to close that gap — giving standards committees a clear basis for recognizing CCA’s copper-like behavior.³

As a result, two new UL proposals, PR43006 (for UL486C) and PR43007 (for UL486A-B), now establish performance criteria specific to Copper-Clad Aluminum. In parallel, the 2026 NEC revision includes 14 AWG and 16 AWG CCA for new circuit categories, marking a turning point in how code bodies treat this conductor material.⁴

What the Data Shows: CCA Is Not Aluminum

Exponent’s testing compared the performance of copper, aluminum, and CCA under identical conditions — using twist-on splice connectors, elevated current loads, and repeated heating cycles. The data was decisive: CCA’s electrical behavior mirrors copper’s and diverges sharply from aluminum’s.

Contact Resistance

Connections made with CCA demonstrated nearly identical contact resistance to copper and less than half that of aluminum.⁵ Even when conductors were intentionally scraped, abraded, or reused in “secondhand” splices, CCA maintained stable, low-resistance performance, while aluminum connections showed significant resistance increases over time.⁶

Temperature Rise

Exponent’s tests also evaluated the temperature rise in splice connections under static heating and accelerated aging conditions. Across 1,000 current cycles at 43 amps, CCA and copper both recorded 0% failures, while aluminum failed up to 90% of the time when exceeding standard temperature limits of 115 °C and 125 °C.⁷

Even when intentionally damaged, CCA showed no increase in temperature rise, reinforcing that the copper cladding protects the conductor from the degradation that affects aluminum’s bare surface.⁸

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Thermal Stability

After 500 heating and cooling cycles, CCA maintained perfect thermal stability, compared with 30% failure for copper and nearly 80% failure for aluminum.⁹

Thermal stability — or the “stability factor” — measures a material’s ability to maintain consistent performance over time. CCA’s superior stability demonstrates its resilience against thermal fatigue, a critical indicator of long-term safety and reliability.

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Durability Under Real-World Handling

Exponent also tested “scraped” and “secondhand” CCA conductors to simulate real-world use. These samples maintained the same conductivity and heating performance as new, unused CCA conductors. The copper cladding preserved a clean, conductive interface even when mechanically disturbed, preventing the nonconductive oxide layer that forms instantly on exposed aluminum.¹⁰

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Independent Validation Drives Standards Reform

Exponent’s findings were reviewed by UL Task Group 69 in early 2025, where the data led to unanimous agreement: Copper-Clad Aluminum must not be derated like aluminum.¹¹ The test results proved that CCA’s performance belongs alongside copper, not below it.

Key updates now in progress include:

• PR43006 (UL486C): Separates Copper-Clad Aluminum from aluminum, using copper’s 75 °C current-cycling column as the performance basis.¹²
• PR43007 (UL486A-B): Introduces new static-heating and current-cycling values for 14 AWG and 16 AWG CCA, with a specific note that these values apply only to CCA conductors.¹³

Together, these proposals ensure that connector ratings and certification pathways align with real-world data. They also clear the way for broader acceptance of CCA in code-compliant applications, reflecting its proven electrical reliability.

Why It Matters

For builders, contractors, electricians, AHJs, architects and specifying engineers, the implications are huge: The CCA performance discussion has moved from debate to data.

CCA’s reliability is no longer a matter of perception or preference — it’s a supported by documented testing. Backed by independent findings, endorsed by standards revisions, and supported by a half-century of successful field use, Copper-Clad Aluminum has earned independent validation as a safe, stable, high-performance electrical conductor.

Copper-Clad Aluminum has earned independent validation as a safe, stable, high-performance electrical conductor.

As UL and NEC updates take effect, professionals can specify CCA with complete confidence. It provides:

• Proven reliability equivalent to copper in all major performance categories
• Stable pricing and lighter weight that improve project efficiency
• Improved energy efficiency and copper conservation that supports sustainability efforts

Reliable by Design

The science behind Copper-Clad Aluminum is straightforward: a metallurgical bond that fuses copper’s electrical performance to aluminum’s light weight and sustainability advantages. The result is a game-changing conductor that optimizes both materials while eliminating the weaknesses of either alone.

Decades of field performance, now reinforced by Exponent’s testing and the resulting standards reforms, affirm Copper-Clad Aluminum’s reliability in modern electrical systems.

With independent verification in place and standards alignment underway, Copperweld Copper-Clad Aluminum stands proven — performing as reliably as copper and far exceeding aluminum in every measure that matters.