50 Amp Wire Size

Recommended conductor sizes for a 50 A circuit under typical conditions (75°C terminations, 30°C ambient, three current-carrying conductors in the raceway). Adjust the conditions below for your job.

Quick answer

MaterialMinimum sizeAmpacity at that size
Copper8 AWG/kcmil50 A
Aluminum6 AWG/kcmil50 A

Calculator

Final ampacity
40 A
Required
50 A
Breaker
50 A
Not adequate for load

Calculation steps

  1. 基准载流量（75°C）
    50 A
    Ref: NEC 310.16
  2. 环境温度 30°C 修正
    1
    Ref: NEC 310.15(B)(1)
  3. 同管 3 根修正
    1
    Ref: NEC 310.15(C)(1)
  4. 修正后载流量
    50 x 1 x 1
    50 A
  5. 端子温度限制（60°C）
    40 A
    Ref: NEC 110.14(C)
  6. 最终允许载流量（取两者较小）
    40 A
  7. 所需电流
    50 A
    Ref: NEC 210.20(A)

本工具结果仅供教育、设计规划与一般信息参考，不构成专业工程建议或持证安装建议。工程规范与电气法规因地区而异，实际安装必须由持证电工依据当地现行法规执行。误用计算结果可能导致电气火灾、设备损坏或违反法规。所有数值请自行核对现行 NEC 版本。

Notes for a 50 A circuit

  • The size above assumes 75°C terminations. If the equipment is only rated 60°C, the usable ampacity drops.
  • Long runs may need a larger conductor to stay within the 3% branch-circuit voltage drop recommendation — check with the voltage drop calculator.
  • Conduit sizing for the chosen conductor is on the conduit fill chart.

Table values pending review against the current NEC edition. Not professional engineering advice.