Copper vs Aluminum Wire: Which Should You Choose?

Introduction

Choosing between copper and aluminum wire is one of the most important decisions in electrical installations. Both materials have distinct advantages and disadvantages that make them suitable for different applications. This guide will help you understand the key differences and make an informed choice.

Copper Wire: The Industry Standard

Advantages of Copper

• Higher Conductivity: Copper conducts electricity 64% better than aluminum, allowing for smaller wire sizes
• Better Flexibility: Copper is more ductile and easier to bend, making installation simpler
• Superior Durability: Less prone to oxidation and corrosion in most environments
• Better Termination: Forms more reliable connections with standard devices
• Longer Lifespan: Typically outlasts aluminum in residential applications

Disadvantages of Copper

• Higher Cost: Significantly more expensive than aluminum
• Heavier Weight: More difficult to handle for large conductors
• Supply Fluctuations: Price volatility due to global market conditions

Aluminum Wire: The Cost-Effective Alternative

Advantages of Aluminum

• Lower Cost: Can be 50-80% cheaper than equivalent copper wire
• Lighter Weight: Easier to handle and install, especially for large sizes
• Good for Large Conductors: Ideal for service entrance and feeder cables
• Corrosion Resistance: Forms protective oxide layer in certain environments

Disadvantages of Aluminum

• Lower Conductivity: Requires larger wire size for same current capacity
• Expansion Issues: Greater thermal expansion can loosen connections over time
• Special Requirements: Needs CO/ALR rated devices and anti-oxidant compound
• Oxidation Concerns: Can form high-resistance oxide layer at connections

Size Comparison

Cost Comparison

While aluminum is cheaper per foot, you need more of it. Consider this example for a 100-foot run at 30 amps:

• Copper: 10 AWG × 100 ft = Higher cost per foot but smaller size
• Aluminum: 8 AWG × 100 ft = Lower cost per foot but larger size needed

Aluminum typically saves 30-50% on material costs for the same installation, making it attractive for large projects.

Best Applications for Each Material

Choose Copper For:

• Residential branch circuits (lighting, outlets)
• Small to medium wire sizes (14-8 AWG)
• Locations requiring flexibility
• Areas with corrosive environments
• Applications where space is limited
• Installations requiring standard devices

Choose Aluminum For:

• Service entrance conductors
• Main feeder cables
• Large wire sizes (6 AWG and larger)
• Long distance power transmission
• Budget-conscious large projects
• Overhead power lines

Installation Considerations

Copper Installation

Copper wire installation is straightforward:

• Use standard wire connectors and devices
• Strip wire cleanly without nicking conductors
• Ensure tight connections
• No special treatment required

Aluminum Installation

Aluminum requires special care:

• Use only CO/ALR or AL/CU rated devices
• Apply anti-oxidant compound to connections
• Use aluminum-rated wire nuts or crimp connectors
• Re-torque connections after initial installation
• Never directly connect copper and aluminum without proper connectors

Safety Concerns with Aluminum

Code Requirements

The National Electrical Code (NEC) allows both copper and aluminum conductors but requires:

• Proper sizing based on ampacity tables (copper and aluminum have different tables)
• Approved connection methods for aluminum
• CO/ALR rated devices for aluminum branch circuits
• Proper marking and identification

Making Your Decision

Choose based on these factors:

1. Application: Branch circuits favor copper; service entrance favors aluminum
2. Budget: Tight budgets on large projects benefit from aluminum
3. Wire Size: Larger sizes (6 AWG+) favor aluminum for cost savings
4. Installation Expertise: Copper is more forgiving for DIY installations
5. Long-term Plans: Consider maintenance and future modifications

Conclusion

Neither copper nor aluminum is universally "better"—each excels in different scenarios. Copper remains the standard for residential branch circuits due to its superior performance and ease of installation. Aluminum shines in large-conductor applications where cost savings justify the extra installation care required.

For most homeowners, copper is the safer choice for branch circuits. For electricians working on commercial projects or service entrance installations, aluminum can provide significant cost savings without compromising safety when properly installed.