Raceway Fill Calculator
Calculate conduit fill percentage according to NEC standards. Determine maximum wire capacity for EMT, PVC, RMC, and other raceway types used in electrical installations.
Step 1: Raceway Information
NEC Fill Requirements
According to NEC Chapter 9, Table 1: 1 conductor = 53% fill, 2 conductors = 31% fill, 3 or more conductors = 40% fill. Always consult local electrical codes for specific requirements.
Step 2: Conductor Information
Conductor Area Reference
Wire area values based on NEC Chapter 9, Table 5. THHN/THWN-2: 14AWG = 0.0097 in², 12AWG = 0.0133 in², 10AWG = 0.0211 in². Ground wires counted at 100% of area for single ground, 25% for multiple.
Raceway Fill Calculation Results
Raceway Fill Percentage
Conduit Fill Capacity Comparison
| Conduit Size | Type | Internal Area (in²) | Max 12AWG THHN (40%) | Max 10AWG THHN (40%) |
|---|
NEC Raceway Fill Reference
NEC Chapter 9, Table 1
Maximum fill percentages:
1 conductor: 53% of raceway internal area
2 conductors: 31% of raceway internal area
3 or more conductors: 40% of raceway internal area
Wire Area Calculation (NEC Table 5)
THHN/THWN-2 conductor areas:
14 AWG: 0.0097 in²
12 AWG: 0.0133 in²
10 AWG: 0.0211 in²
8 AWG: 0.0366 in²
6 AWG: 0.0507 in²
Raceway Internal Area (NEC Table 4)
EMT internal areas:
1/2″: 0.304 in²
3/4″: 0.533 in²
1″: 0.864 in²
1 1/4″: 1.496 in²
1 1/2″: 2.036 in²
Grounding Conductors
NEC 250.122: Equipment grounding conductors sized according to overcurrent protection. For fill calculations, count one grounding conductor at 100% of its area. Multiple grounding conductors counted at 25% each.
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