Neutral Conductor Sizing Calculator

Size neutral conductors for balanced and unbalanced loads per NEC.

Phase Loads (Amps)

NEC Neutral Requirements

  • 220.61: Neutral load is maximum unbalanced load
  • 220.61(B): Neutral can be reduced to 70% for portion over 200A
  • Exception: No reduction for non-linear loads (3rd harmonic)
  • 250.24(C): Grounded conductor sized per 250.66
  • 310.15(E): Neutral counts as current-carrying for non-linear loads

Conductor Ampacity (NEC 310.16 - 75C Column)

Size Copper Aluminum Typical Use
6 AWG55A45ASmall subpanels
4 AWG70A55ASubpanels
2 AWG95A75A100A service
1/0 AWG125A100A125A service
2/0 AWG145A115A150A service
3/0 AWG165A130A175A service
4/0 AWG195A150A200A service
250 kcmil215A170A225A service
350 kcmil260A205A300A service
500 kcmil320A260A400A service