Calculadora de Llenado de Conduit — Fórmula

NEC Conduit Fill Rules

The National Electrical Code limits fill percentages to prevent overheating:

  • 1 conductor: 53%
  • 2 conductors: 31%
  • 3 or more: 40%

    • Calculate fill by dividing total conductor area (including insulation) by the conduit internal area.

    Ejemplo Resuelto

    4 conductors of 12 AWG THHN (0.0973 sq in each) in 3/4-inch EMT (0.864 sq in).

    1. Total wire area = 4 x 0.0973 = 0.389 sq in
    2. Fill = 0.389 / 0.864 x 100 = 45.0%
    3. NEC allows 40% for 3+ conductors
    4. This conduit is overfilled; upsize to 1-inch EMT.