Conduit Size Calculator
Calculate the proper conduit size needed for your electrical wires. Understand NEC guidelines for conduit fill based on wire types, sizes, and quantities.
Step 1: Wire Details
NEC Conduit Fill Guidelines
NEC guidelines limit conduit fill to prevent overheating and allow for wire pulling. For 1-2 wires: max 53% fill. For 3+ wires: max 40% fill. Always consult local codes.
Step 2: Installation Details
About Conduit Fill
Conduit fill is calculated based on wire cross-sectional area and conduit internal area. More wires, larger wires, or more bends require larger conduit sizes for proper installation and heat dissipation.
Conduit Size Results
Minimum Required Conduit Size
Conduit Size Comparison
| Conduit Size | Internal Area | Fill Percentage | NEC Compliance | Typical Use |
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Conduit Fill Analysis
Conduit Fill Formula
Fill % = (Total Wire Area ÷ Conduit Internal Area) × 100
The conduit fill percentage is calculated by dividing the total cross-sectional area of all wires by the internal area of the conduit, then multiplying by 100. NEC limits this to 40% for 3 or more current-carrying conductors.
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