NEC Compliant
Conduit Fill Calculator
Calculate conduit fill ratio for wire bundles. Ensures proper cable routing and NEC compliance.
Conduit Fill Calculator
Calculate fill percentage per NEC requirements
Article 300
NEC Conduit Fill Limits
Maximum fill percentages per the National Electrical Code.
53%
1 Wire
Single conductor in conduit allows maximum fill percentage.
31%
2 Wires
Two conductors reduce maximum fill to allow for heat dissipation.
40%
3+ Wires
Three or more conductors - standard limit for most installations.
Why Conduit Fill Matters
- Heat dissipation: Overcrowded conduit traps heat, degrading insulation
- Wire pulling: Proper fill makes installation easier and prevents damage
- Code compliance: Exceeding NEC limits can fail inspection
- Future expansion: Leave room for adding circuits later
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