What Size Wire for a 50 Amp Circuit Breaker? (NEC Table 310.16)

Complete Copper vs. Aluminum AWG wire size, continuous load limit (40A max), ground wire gauge, and conduit sizing for 50A circuits (40A Level 2 EV chargers (NEMA 14-50), hot tubs, spas & 50A RV outlets).

Direct NEC Table 310.16 Answer for 50 Amps

6 AWG
Minimum Copper Wire (75°C)
THHN / THWN-2 / XHHW in Conduit
4 AWG
Minimum Aluminum Wire (75°C)
SER / XHHW-2 Feeder Cable
40 Amps
Max Continuous Load (80% Rule)
For loads running 3+ hours (EVs, lighting)
3/4" EMT
Recommended Conduit Size
Fits 3x 6 AWG + Ground under 40% fill

Common Applications for a 50A Circuit

40A Level 2 EV chargers (NEMA 14-50), hot tubs, spas & 50A RV outlets. Remember that under the NEC 125% continuous-load rule (NEC 210.19 & 210.20), a standard 50A breaker can only supply up to 40A of continuous load (any load that runs for 3 hours or more without stopping, such as an EV charger or commercial lighting).

When to Upsize for Voltage Drop (Over 100 Feet)

If your one-way wire run exceeds 100 feet at 240V (or 50 feet at 120V), step up one wire gauge from 6 AWG to keep total line voltage drop under the NEC 3% branch-circuit recommendation. Use our Voltage Drop Calculator to check your exact footage.

2. NEC Wire Size & Ampacity Calculator (Table 310.16)

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