Conduit Fill Calculator

Check whether a set of conductors fits within a conduit according to NEC fill percentage rules.

sq in
sq in

Conduit Fill

45.0 %

NEC Max Fill40 %
Remaining Area-0.0436 sq in

Conduit Fill vs Conduit Internal Area

सूत्र देखें →

सूत्र

## 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.

हल किया गया उदाहरण

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

  1. 01Total wire area = 4 x 0.0973 = 0.389 sq in
  2. 02Fill = 0.389 / 0.864 x 100 = 45.0%
  3. 03NEC allows 40% for 3+ conductors
  4. 04This conduit is overfilled; upsize to 1-inch EMT.