Wire Gauge for 50A at 100 ft on 240V — NEC Calculator
For 50A at 100 ft on 240V, use 6 AWG copper. Voltage drop: 2.05%. Per NEC 2023 Table 310.16.
▸ Advanced options — derating, breaker & conduit
6 AWGcopper
Ampacity OKVD 2.05%
6 AWG selected by ampacity (55A ≥ 50A).
55A
Ampacity
at 60°C
2.05%
Voltage drop
4.92V
235.1V
At load
receiving end
26,240
Circular mils
13.3 mm²
Min for ampacity ← governs
6 AWG
26,240 CM
Min for ≤3% VD
6 AWG
26,240 CM
50A
Breaker size
NEC 240.6(A)
~$370
Wire cost est.
200 ft THHN
1-1/4" EMT
Conduit size
3 conductors
10 AWG Cu
Ground wire (EGC)
NEC 250.122
239.5W
Power loss
~$293.72/yr
Copper vs Aluminum (for 50A at 100 ft on 240V)
Copper
6 AWG
VD: 2.0% · 13.3 mm²
Aluminum
4 AWG
VD: 2.1% · 21.1 mm²
What wire gauge for 50A at 100 ft on 240V?
For a 50A circuit at 100 ft on 240V, use 6 AWG copper conductor.
6 AWG (55A ampacity) satisfies both the 50A load and 3% voltage drop limit at 100 ft.
Recommended wire gauge
Ampacity governs
6 AWG copper
55A ampacity | 2.05% VD | 235.1V at load
Minimum wire by constraint
Required CMs: 17,917 CM. Formula: CM = (2 × K × I × L) / (V × 3%)
Wire size by run distance
Distance sensitivity for 50A on 240V at 3% voltage-drop target.
Copper vs aluminum for this run
Material comparison uses the same amps, voltage, distance, temperature rating, and voltage-drop limit.
Protection, conduit, cost, and loss planning
These planning values are generated from the recommended conductor and are not a substitute for field code review.
Sizing assumptions
Sizing uses copper conductor data, 60C ampacity, single-phase voltage drop, 3% maximum voltage drop, not more than 3 current-carrying conductors, and 30C ambient.
The recommended wire is the larger of the ampacity minimum and the voltage-drop minimum. Long runs can require upsizing even when ampacity alone passes.
Breaker sizing, equipment grounding conductor sizing, conduit estimate, power loss, and cost are computed from the recommended conductor for planning context.
Safety and code review notes
Use the equipment nameplate and local code as the final authority. HVAC, EVSE, motors, continuous loads, and feeders often have extra NEC rules beyond a simple amps-and-distance calculation.
Aluminum conductors require listed AL/CU terminations and installation practices appropriate to the conductor and environment.
This sizing passes the modeled checks under the stated assumptions.
Step-by-step wire sizing
Load: 50A at 240V (single-phase), 100 ft, copper at 60°C
Step 1 — Ampacity: find smallest wire where derated ampacity ≥ 50A → 6 AWG (base 55A, no derating)
Step 2 — Voltage drop: allowed VD = 240V × 3% = 7.199999999999999V
CM = (2 × 12.9 × 50A × 100ft) / 7.199999999999999V = 17,917 CM → 6 AWG
Step 3 — Recommended: 6 AWG (ampacity governs)
Breaker: NEC 240.6(A): use 50A breaker (next standard size ≥ 50A)
Ground wire: NEC Table 250.122: 50A OCPD → EGC ≥ 10 AWG Cu (or 8 AWG Al)
Power loss: 239.5W in run — ~2098 kWh/yr (~$293.72/yr @ $0.14/kWh)
Cost: ~$1.85/ft × 200 ft = ~$370 (2024 retail THHN)
Conduit: minimum 1-1/4" EMT for 3 conductors of 6 AWG
Verification: 55A ≥ 50A ✓ | VD 2.05% ≤ 3% ✓