Practical Cable Sizing

Copper vs Aluminum Conductors: When Each Makes Sense

Copper and aluminum each have genuine advantages depending on the application — a practical comparison, not a blanket recommendation.

The copper-vs-aluminum conductor question comes up often, and the honest answer is that each has genuine advantages depending on the specific application — neither is universally correct.

Copper's Advantages

• Higher ampacity per unit cross-sectional area — a smaller copper conductor carries the same current as a larger aluminum one
• Better mechanical properties for repeated flexing and smaller termination sizes
• More forgiving of minor installation imperfections at terminations

Aluminum's Advantages

• Significantly lower cost per unit of current-carrying capacity, especially meaningful on large commercial and utility-scale feeders
• Lighter weight — a real practical advantage on long overhead or large commercial runs

Where Aluminum Needs Extra Care

Aluminum terminations require correctly rated (AL-CU or AL-rated) connectors and, in many jurisdictions, specific anti-oxidant compound application — aluminum's oxide layer and thermal expansion characteristics make termination quality more consequential than with copper, a genuine reason some installers prefer copper for smaller, termination-dense residential work despite the cost difference.

The Practical Guidance

Larger commercial and utility-scale feeders often favor aluminum for cost and weight; smaller residential and light commercial circuits, where termination density is high and cost difference is less consequential, often favor copper.

Engr. Jason Morales — Founder, SolarEnergyPH & OhmWorks

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