Voltage Drop for 80 A Over 200 ft at 480 V — What Wire Size?
Short answer: 4 AWG copper holds the drop to 2.05% over 200 ft at 80 A on a 480 V circuit — inside the 3% figure the NEC recommends for a branch circuit.
Every gauge over this run
| Conductor | Drop | Drop % | vs 3% |
|---|---|---|---|
| 14 AWG | 100.48 V | 20.93% | over |
| 12 AWG | 63.36 V | 13.2% | over |
| 10 AWG | 39.68 V | 8.27% | over |
| 8 AWG | 24.9 V | 5.19% | over |
| 6 AWG | 15.71 V | 3.27% | over |
| 4 AWG | 9.86 V | 2.05% | ≤ 3% |
| 3 AWG | 7.84 V | 1.63% | ≤ 3% |
| 2 AWG | 6.21 V | 1.29% | ≤ 3% |
| 1 AWG | 4.93 V | 1.03% | ≤ 3% |
| 1/0 | 3.9 V | 0.81% | ≤ 3% |
| 2/0 | 3.09 V | 0.64% | ≤ 3% |
| 3/0 | 2.45 V | 0.51% | ≤ 3% |
Why this is a recommendation, not a violation
Voltage drop lives in NEC 210.19(A) and 215.2(A) informational notes — 3% on a branch circuit and 5% total including the feeder. Informational notes are not enforceable requirements, so a set will not usually be rejected purely for drop. That is exactly why it gets ignored, and why it keeps showing up as a performance complaint after commissioning.
On a PV circuit the loss is real energy: at 2.05% you are giving up roughly that fraction of production on this run, every hour it operates, for the life of the system. At 200 ft the conductor upgrade usually pays for itself long before the array does.
The 480 V effect
Percentage drop scales inversely with system voltage: the same conductor carrying the same current shows a larger percentage the lower the voltage. At 480 V this run is comparatively forgiving — the identical conductor at 240 V would show roughly double this percentage, and at 208 V a little more than double. That is the argument for running long feeders at higher voltage.
Related
Computed with OneLine Studio's NEC engine — the same deterministic code tables that size a real permit set, not an estimate. Conductor ampacity from NEC 310.16, correction factors from 310.15(B)(1), fill adjustment from 310.15(C)(1). Always confirm the enforced NEC edition and any local amendments with your AHJ.
FAQ
What wire size for 80 A over 200 ft at 480 V?
4 AWG copper keeps voltage drop at 2.05%, within the NEC's 3% branch-circuit recommendation. Ampacity may require a different size — check 690.8 and 310.16 as well, and take whichever is larger.
Is exceeding 3% a code violation?
No. The 3% and 5% figures are in informational notes to 210.19(A) and 215.2(A), which are not enforceable. They are strong engineering guidance, and on a PV circuit the drop is lost production for the life of the system.
Educational reference, reviewed 2026-07. A design aid, not a substitute for a licensed electrician or PE. Confirm the enforced NEC edition and local amendments with your AHJ.
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