Use our free Cable Duct Size Calculator to determine the ideal internal dimensions for circular or square electrical conduits and ducts. Ensure compliance and efficient cable management with accurate calculations for your residential, commercial, or industrial projects. Easily find the minimum duct diameter or side length required.
Formula:
To determine the minimum cable duct size, we first calculate the total cross-sectional area of all cables. Then, based on your desired fill percentage (e.g., NEC guidelines), we calculate the required internal duct area and subsequently the minimum internal diameter for circular ducts or side length for square ducts.
1. Area of a Single Cable: Acable = π * (d/2)2
2. Total Cable Area: Atotal = N * Acable
3. Minimum Duct Area: Aduct = Atotal / (Fill % / 100)
4. Minimum Circular Duct Diameter: Dcircular = 2 * √(Aduct / π)
5. Minimum Square Duct Side: Ssquare = √(Aduct)
Where:
N = Number of cables
d = Outer diameter of a single cable (mm)
Fill % = Desired duct fill percentage (e.g., 40, 50, 60)