Conductor Material Comparison Chart

Use this worksheet after wire-size or ampacity calculator results to compare conductor material, adjusted ampacity, voltage drop, termination compatibility, raceway impact, and installation requirements.

Open calculator

Quick reference table

Copper and aluminum are not one-size substitutions. Run the calculator separately for each material, then compare adjusted ampacity, voltage drop, conductor size, terminal compatibility, torque instructions, raceway fill, pulling space, and equipment markings before selecting a conductor for project review.

Copper and aluminum worksheet comparison

Copper and aluminum worksheet comparison
Decision area	Copper record	Aluminum or CCA record
Calculator result	Conductor size, ampacity basis, and adjustment factors	Separate size, ampacity basis, and adjustment factors
Voltage drop	Modeled drop and percent for the run	Modeled drop and percent for the same load and length
Termination	Terminal temperature and material marking	AL/CU or material marking, preparation, and torque notes
Raceway impact	Conduit fill, pulling, bend space, and lug fit notes	Larger conductor, fill, pulling, bend space, and enclosure impact
Verification	Equipment, manufacturer, utility, and AHJ notes	Equipment, manufacturer, utility, and AHJ notes

Material decision triggers after calculator results

Material decision triggers after calculator results
Trigger	Why it matters	Next check
Aluminum result uses larger size	Raceway and termination space can change	Conduit fill, bend space, lug size, and pull plan
Long feeder run	Voltage drop may drive conductor size	Run voltage-drop calculator for each material
Existing equipment terminals	Lugs may not accept all materials or sizes	Equipment marking and manufacturer instructions
Cost-driven substitution	Lower material cost can create installation cost	Labor, raceway, pulling, torque, and inspection notes

Formula basis

Material comparison = calculator ampacity result + voltage-drop result + termination compatibility + raceway impact + equipment verification.

Conductor material is copper, aluminum, or copper-clad aluminum as supported by the calculator and equipment.
Adjusted ampacity is the conductor ampacity after applicable temperature and count adjustments.
Voltage drop is the modeled circuit drop for the selected material, distance, current, and voltage.
Termination compatibility confirms whether equipment is marked and instructed for the selected conductor material.

Worked examples

Feeder material comparisonRun the wire-size calculator for copper and aluminum separately. Record final ampacity, voltage drop, terminal compatibility, and raceway impact before choosing which result moves forward.

Long run where voltage drop controlsIf both materials meet ampacity, rerun voltage drop for the same load and length. The larger aluminum conductor may be driven by voltage drop or terminal fit rather than ampacity alone.

Assumptions. Balanced load and line-to-line voltage assumptions behind this chart.

The worksheet assumes each material option was calculated with its own ampacity and resistance basis.
The worksheet does not approve material substitution without equipment compatibility, conductor preparation, torque, product listing, and AHJ review.
The adopted NEC edition, equipment listing, manufacturer instructions, utility requirements, and AHJ interpretation must be verified before final material selection.

Code and standard notes. Planning limits that should be checked before final equipment selection.

Use this worksheet as an educational planning record; verify adopted NEC rules, equipment listings, manufacturer instructions, torque data, utility requirements, and AHJ requirements before final material selection.

How to use this chart

1Run separate calculationsUse the calculator separately for each material option instead of scaling one material result into another.

2Compare more than ampacityRecord voltage drop, raceway fit, terminal markings, preparation, and torque requirements alongside ampacity.

3Document final basisKeep selected material, size, termination rating, equipment marking, and manufacturer notes visible before carrying the result forward.

Worksheet checklist. Record source basis, review gaps, and assumptions before using the chart result.

Record calculator outputsWrite conductor size, adjusted ampacity, voltage drop, OCPD basis, and sizing driver for each material option.
Record equipment checksDocument terminal material marking, temperature rating, conductor preparation, and torque instructions for the selected equipment.
Record installation impactNote raceway fill, pulling space, bend space, support, enclosure changes, and inspection notes that follow from material choice.

Common mistakes to avoid. Review these before turning chart current into an equipment decision.

Treating copper and aluminum as interchangeable without rerunning ampacity, voltage-drop, and termination checks.
Selecting a conductor by material cost alone while missing lug listing, torque, preparation, raceway fill, or bend-space requirements.
Checking ampacity only and discovering later that the selected equipment cannot accept the conductor material or size.

Frequently asked questions

These answers explain how to use the chart without turning a quick reference into a final design decision.

Can aluminum simply replace copper at the same size?

No. Aluminum usually needs a separate ampacity and voltage-drop calculation, plus equipment and installation compatibility checks.

Why include raceway impact?

A larger conductor can change conduit fill, pulling conditions, bend space, lug fit, and enclosure layout even when ampacity is acceptable.

What should be checked at the termination?

Check material marking, conductor size range, temperature rating, torque instructions, preparation requirements, and manufacturer documentation.