Commercial Conduit Fill Calculator
Calculate conduit fill for commercial building electrical systems with our free, NEC-compliant calculator. This tool is designed for commercial applications including lighting circuits, three-phase power distribution, HVAC systems, and larger load requirements typical in commercial buildings.
Whether you're installing lighting controls, power distribution for office equipment, three-phase motors, or electrical service for retail spaces, our calculator ensures your commercial conduit installations meet all National Electrical Code requirements for safe and compliant building wiring.
Input Parameters
Conductors
Results
Visual Representation
Enter conduit and wire information to see results
NEC Fill Requirements
According to NEC Chapter 9, Table 1: 1 conductor = 53% max, 2 conductors = 31% max, 3+ conductors = 40% max, Nipples = 60% max
Commercial Electrical Circuit Examples
Lighting Circuits:
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Fluorescent Lighting (20A)12 AWG THHN, 3/4" or 1" EMT
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LED Lighting with Controls (20A)12 AWG THHN, 3/4" EMT
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Outdoor Signage (20-30A)12-10 AWG THHN, 3/4" to 1" EMT
Power Distribution:
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Three-Phase Motors (30-60A)10-4 AWG THHN, 1" to 1-1/2" EMT
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HVAC Units (40-100A)8-1 AWG THHN, 1-1/4" to 2" EMT
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Panelboard Feeders (100-400A)1 AWG to 500 kcmil, 2" to 4" EMT
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All conduit types and configurations