600 kcmil Wire Ampacity & Specifications
600 kcmil copper wire carries 420A at 75°C (NEC Table 310.16), or 340A for aluminum; copper is typically protected by a 400A 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.
600 kcmil wire has an ampacity of 420A at 75°C for copper and 340A for aluminum (NEC Table 310.16). Its 60°C and 90°C copper ratings are 350A and 475A. Copper 600 kcmil is commonly protected by a 400A breaker.
Copper 75°C
420A
Copper 90°C
475A
Aluminum 75°C
340A
Copper breaker (75°C)
400A
600 kcmil Wire Specifications
| Ampacity — Copper (60 / 75 / 90°C) | 350 / 420 / 475 A |
| Ampacity — Aluminum (60 / 75 / 90°C) | 285 / 340 / 385 A |
| Cross-section | 600,000 circular mils |
| DC resistance — Copper | 0.0214 Ω / 1000 ft |
| DC resistance — Aluminum | 0.0353 Ω / 1000 ft |
| Typical voltage drop (240V) | 0.4% at 50 ft · 0.7% at 100 ft (at 400A) |
Common Uses for 600 kcmil Wire
- 420A copper feeders
- Service entrances (often paralleled)
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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