Conductor Reference
Copper vs Aluminum Wire
Ampacity, sizing, cost, and terminations side by side, so you can decide which conductor to pull and how far to upsize if you go aluminum. Every ampacity is straight from NEC Table 310.16.
Ampacity from NEC Table 310.16 (75°C column); dwelling service sizes from NEC 310.12; termination rules from NEC 110.14. NFPA 70 2023. Confirm your termination temperature rating and your AHJ’s adopted code edition.
Copper vs Aluminum, Side by Side
| Attribute | Copper | Aluminum |
|---|---|---|
| Ampacity for the same conductor size | Baseline (100%) | About 75-80% of copper |
| Size needed to carry the same load | Baseline | About two AWG sizes larger |
| 100 A feeder conductor (75°C) | #3 (100 A) | #1 (100 A) |
| 200 A dwelling service (NEC 310.12) | 2/0 AWG | 4/0 AWG |
| Smallest size in Table 310.16 | #14 AWG | #12 AWG (no #14 aluminum) |
| Typical material cost per ampere | Higher | Lower, widening on large feeders |
| Terminations (NEC 110.14) | Standard lugs | AL-rated (CO/ALR, AL9), antioxidant, torqued |
| Raceway / conduit size | Smaller | Larger (upsized conductor) |
| Weight | Heavier | Roughly half |
| Where it fits best | Branch circuits, feeders, services | Larger feeders and services |
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Dwelling Service and Feeder Sizes (NEC 310.12)
For the main power feeder or service to a one-family dwelling, NEC 310.12 allows a smaller conductor than Table 310.16 (the 83 percent allowance), which is why residential services use these familiar sizes. This is the fast path for a house; feeders to subpanels and everything else size from Table 310.16.
| Service size | Copper | Aluminum / copper-clad aluminum |
|---|---|---|
| 100 A | 4 AWG | 2 AWG |
| 125 A | 2 AWG | 1/0 AWG |
| 150 A | 1 AWG | 2/0 AWG |
| 200 A | 2/0 AWG | 4/0 AWG |
Which One Should You Pull?
- Large feeders and services lean aluminum. On a 100 A subpanel feeder or a 200 A service, the material savings on aluminum are real and the upsize is easy to accommodate. 4/0 aluminum service-entrance cable is the residential default for a reason.
- Branch circuits lean copper. For 15 and 20 A circuits, aluminum is rarely worth it: it starts at #12, the terminations are fussier, and the material savings are tiny at small sizes. Almost all modern branch wiring is copper.
- Aluminum upsizes conduit too. The larger conductor takes more raceway fill, so an aluminum run can need a bigger conduit than the copper equivalent. Check fill before you commit to a raceway size.
- Terminations are where aluminum jobs go wrong. Use AL-rated devices and lugs (CO/ALR, AL9, or dual-rated), apply antioxidant where the listing calls for it, and torque to spec per NEC 110.14. A loose aluminum termination is the classic failure, not the wire itself.
Frequently Asked Questions
Is aluminum wire as good as copper?
For feeders and services, modern aluminum (the AA-8000 alloy series developed in the early-to-mid 1970s and later required by code) is a code-accepted, reliable conductor used every day on service entrances and large feeders. It is not the old solid AA-1350 aluminum branch-circuit wiring from the late 1960s and early 1970s that earned aluminum its bad reputation. The trade-offs are physical, not a safety verdict: aluminum carries about three-quarters of copper's ampacity for the same size, so it upsizes, and it must land on terminals rated for aluminum with an antioxidant compound and correct torque.
How many sizes up do you go for aluminum wire?
Roughly two AWG sizes, because aluminum's ampacity is about 75 to 80 percent of copper's at the same size. Do not eyeball it: size from the aluminum column of NEC Table 310.16 for your load and termination rating. For example, a 100 A feeder at the 75°C rating is #3 copper (100 A) or #1 aluminum (100 A).
Can I use aluminum wire for a 200 amp service?
Yes, and it is the common choice. NEC 310.12 gives a dedicated dwelling service and feeder table (the 83 percent allowance for the main power feeder to a home): a 200 A service is 2/0 copper or 4/0 aluminum. 4/0 aluminum service-entrance cable is standard on residential 200 A services precisely because it is far cheaper than 2/0 copper for the same job.
Can I mix copper and aluminum on the same terminal?
Only on a device or connector listed for both, and only per its listing. Copper and aluminum have different expansion rates and aluminum oxidizes, so a copper-only lug with aluminum in it loosens and overheats. Use CO/ALR-rated receptacles and switches, AL9 or dual-rated lugs, an antioxidant compound where required, and the manufacturer's torque spec per NEC 110.14.
Related Tools
Wire Size Calculator
Size copper or aluminum from NEC Table 310.16 with temperature correction and derates.
Wire Ampacity Chart
Full NEC 310.16 ampacities for copper and aluminum at 60, 75, and 90°C.
Voltage Drop Calculator
Aluminum drops more voltage per foot than copper. Check the run before you upsize.
Ground Wire Size Chart
Equipment grounding conductor sizes for copper and aluminum per NEC 250.122.
Pick the conductor, then size it right.
Once you have chosen copper or aluminum, the wire size calculator handles the ampacity, temperature correction, and derates from NEC Table 310.16.