The Battle of Metals in the Electrical Industry: Comprehensive Comparison of Copper and Aluminum Cables

Introduction: The Great Dilemma in Electrical Projects

For over a century, copper has been the undisputed king of the electrical industry. Wherever energy transmission was discussed, copper wires and cables were present due to their exceptional conductivity. But in recent decades, with the skyrocketing global price of copper and the need to reduce infrastructure project costs, a powerful and economical competitor has entered the field: aluminum.

Today, contractors, consulting engineers, and project owners face a strategic question at the start of every major project (from urban electrification to industrial feeders): “Do we remain loyal to copper and pay its heavy cost, or switch to aluminum cables? Is aluminum technically reliable?”

The answer is not a simple “yes” or “no.” The choice between these two metals requires a deep understanding of their inherent differences in conductivity, weight, mechanical strength, and chemical behavior. In this analytical article from the technical unit of Sim Rad Sama, we intend to place these two giants of the wire and cable industry on the scale without bias and based on engineering data.

Part One: Technical and Engineering Comparison

The most important part of decision-making is understanding the physical and electrical differences between these two metals. Let’s compare them head-to-head:

1. Electrical Conductivity

This is copper’s realm of dominance.

• Copper: The international standard of electrical conductivity (IACS) is defined based on annealed copper, considered 100%. Copper is the best economical conductor available to mankind.

• Aluminum: The electrical conductivity of pure aluminum is about 61% of copper’s conductivity.

Operational meaning: To transmit a specific amount of electrical current using an aluminum cable, you must increase the cable’s cross-sectional area (thickness).

Rule of thumb: To replace a copper cable with an aluminum cable of the same current capacity, the aluminum cable’s cross-section must be about 1.6 times larger (two standard sizes up). For example, replacing a 70 mm² copper cable with a 120 mm² aluminum cable.

2. Weight and Density

Here is aluminum’s main trump card.

• Density of copper: approx. 8.9 g/cm³

• Density of aluminum: approx. 2.7 g/cm³

Surprising result: Aluminum weighs almost one-third of copper! Even though for equal current you must choose a thicker aluminum cable (according to section 1), the final weight of the aluminum cable will still be about half that of its equivalent copper cable.

• Advantage: Lower weight means easier transport, smaller reels, less labor for installation, and less stress on supporting structures (cable trays or utility poles).

3. Corrosion Resistance

• Copper: Resistant in normal environments but corrodes in acidic or ammonia-rich environments (green patina).

• Aluminum: When exposed to air, a thin but highly resistant layer of aluminum oxide immediately forms on its surface, acting as a protective shield and preventing further corrosion. This feature makes aluminum cables (especially self-supporting types) perform excellently in humid and tropical environments.

The Connection Challenge: This same protective oxide layer is an electrical insulator! If, when connecting an aluminum cable to equipment (which typically has copper terminals), this oxide layer is not properly removed or unsuitable lugs are used, the connection resistance will increase, overheat, and may cause a fire.

• Sim Rad Sama solution: Mandatory use of bi-metal lugs and anti-oxidant paste at aluminum-to-copper connection points.

4. Mechanical Properties (Flexibility and Creep)

• Ductility (Flexibility): Copper is softer and more flexible. Working with copper cables in tight spaces (e.g., electrical panels) is easier. Aluminum is drier and more brittle, and should not be bent excessively.

• Creep phenomenon: Aluminum under pressure (e.g., under a terminal screw) gradually deforms and becomes “loose”. This phenomenon is much less common in copper. However, this problem in modern aluminum cables has been largely solved using modern alloys (AA-8000 series).

Summary Table: Quick Comparison of Copper and Aluminum Cables

This table summarizes all the key parameters reviewed above to make decision-making easier for you.

Part Two: Economic Analysis (Cost or Investment?)

Here the tables turn completely in aluminum’s favor. The price of copper in global markets fluctuates like a precious metal and is always several times that of aluminum.

• Purchase cost: An aluminum cable can be 30-50% cheaper than its equivalent copper cable. In large projects such as industrial feeders, power transmission lines, or large residential complexes, this price difference amounts to billions of tomans.

• Theft risk: Copper cables are always attractive targets for thieves. Aluminum cables, due to their much lower scrap value, are safe from theft.

Economic conclusion: If you are not space-constrained (so you can use a thicker aluminum cable), choosing aluminum is an economically intelligent decision.

Part Three: Practical Guide for Cable Selection

The final choice depends on the nature of your project. Sim Rad Sama engineers suggest this categorization:

✅ Absolute Realm of Copper (Where only copper should be used?)

1. Internal building wiring: For outlets, lighting, and switches (small sizes below 10 mm²) — using aluminum is prohibited or non-standard.

2. Tight and vibrating spaces: Dense electrical panels, moving equipment (e.g., cranes), and industrial machinery requiring highly flexible cables.

3. Sensitive equipment: Facilities where the slightest voltage drop or connection risk is unacceptable (e.g., data centers or critical sections of hospitals).

✅ Golden Realm of Aluminum (Where aluminum is better?)

1. Overhead distribution networks (ABC): Self-supporting cables, now the standard of distribution networks, are entirely made of aluminum. Their low weight allows utility poles to be installed at greater distances.

2. Underground power feeders: For transmitting power from transformer substations to the main panel of factories or complexes.

3. Power transmission lines: All the high-voltage towers you see on roads use aluminum conductors (ACSR). Using copper at this scale is impossible.

Part Four: Practical Size Conversion Table (Copper to Aluminum)

One of the engineers’ recurring questions: “If I want to replace the copper cable, exactly what size aluminum cable should I buy?”

In the table below, based on the standard allowable current (at 25°C in air), we have provided common equivalents. This table can serve as your purchasing guide from Sim Rad Sama:

Engineering note: As you can see, by going up two size steps (e.g., from 70 to 120), the current capacity of the aluminum cable often exceeds that of the original copper cable, and you can be assured regarding voltage drop.

Part Five: Environmental Impact and Recycling (Green Energy)

Today in green-certified construction projects (LEED), attention to materials used is very important.

• Production energy: Extracting and refining aluminum consumes a lot of energy, but recycling it is extremely low-energy. Recycling aluminum requires only 5% of the energy of primary production.

• Life cycle: Standard aluminum cables have a lifespan of over 30 years. After their useful life, Sim Rad Sama aluminum cables are fully recyclable and return to the production cycle without any loss of metal quality. This feature makes using aluminum in distribution networks a sustainable choice for the environment.

Conclusion: Aluminum is an Engineered Alternative

Viewing aluminum cable as “second-class material” or “just cheap” is a big mistake. Aluminum is an “engineered alternative.” If these cables are properly sized (selecting the appropriate cross-section) and their connections are made using bi-metal lugs and precision tools (torque wrench), they will perform exactly like copper, except that they will halve your project cost.

At Sim Rad Sama factory, we produce both copper and aluminum cables to the highest national and international standards. Our commitment is to provide a product that, regardless of the conductor material, ensures the safety and durability of your project.

If you are still undecided between the two, our technical experts are ready to offer you the best option through precise calculations.

Frequently Asked Questions (FAQ)

1. Do aluminum cables cause fires?
No, aluminum cable is not dangerous by itself. Fire occurs when its connection to copper equipment is incorrect (using unsuitable lugs or not using anti-oxidant paste). With proper installation practices, these cables are completely safe.

2. Can I use aluminum for my home wiring?
For internal wiring (outlets and lighting), no. Iranian building standards (Article 13 of the National Regulations) do not permit the use of small cross-section aluminum wires inside buildings.

3. Why do power distribution companies use only aluminum self-supporting cables?
For three main reasons: 1) Much lower weight, reducing the need for strong utility poles, 2) Much lower cost in huge lengths, and 3) No attraction for wire thieves.

4. How do I convert copper cable size to aluminum?
As a general rule, you should go up two standard sizes. For example, if your calculations indicate a 25 mm² copper cable, you should use a 50 mm² aluminum cable. For greater accuracy, standard allowable current tables should be used.