500 kcmil Wire Ampacity & Specifications
500 kcmil copper wire carries 380A at 75°C (NEC Table 310.16), or 310A for aluminum; copper is typically protected by a 350A breaker.
Calculations are built on the 2023 National Electrical Code (NEC) and cross-checked against the published code tables. How we verify. Last updated June 2026.
500 kcmil wire has an ampacity of 380A at 75°C for copper and 310A for aluminum (NEC Table 310.16). Its 60°C and 90°C copper ratings are 320A and 430A. Copper 500 kcmil is commonly protected by a 350A breaker.
Copper 75°C
380A
Copper 90°C
430A
Aluminum 75°C
310A
Copper breaker (75°C)
350A
500 kcmil Wire Specifications
| Ampacity — Copper (60 / 75 / 90°C) | 320 / 380 / 430 A |
| Ampacity — Aluminum (60 / 75 / 90°C) | 260 / 310 / 350 A |
| Cross-section | 500,000 circular mils |
| DC resistance — Copper | 0.0258 Ω / 1000 ft |
| DC resistance — Aluminum | 0.0424 Ω / 1000 ft |
| Typical voltage drop (240V) | 0.4% at 50 ft · 0.8% at 100 ft (at 350A) |
Common Uses for 500 kcmil Wire
- 380A copper feeders
- Large commercial/industrial feeders
Ampacities are from NEC Table 310.16. Copper 14, 12 and 10 AWG are limited to 15A, 20A and 30A overcurrent protection, aluminum 12 and 10 AWG to 15A and 25A (240.4(D)). Terminations rated 60°C or 75°C usually cap the usable ampacity below the 90°C value.
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