Network & Power
Conduit fill
Cables in the run → minimum conduit size (NEC Chapter 9 fill rules).
List the cables you're pulling — Cat6, HDMI, fibre, speaker. Get back the minimum EMT trade size that satisfies NEC fill ratios (53% for 1 cable, 31% for 2, 40% for 3+). Common AV cable cross-sections built in; rounds up to the next standard conduit size.
cables in this run
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Minimum conduit (EMT trade size)
1-1/4"
10 conductors total · 40% NEC fill limit applies
Required inside diameter
31.6mm
total cable area 314 mm² ÷ 40% fill = 785 mm² required
- NEC Chapter 9 fill: 53% (1 cable) · 31% (2) · 40% (3+)
- round up to next trade size — never down
- account for bends: 90° bend = ~20 ft penalty on pulls
- add 25% if conduit will be re-pulled later
cross-section
Cables packed inside 1-1/4" EMT. The ring on the right shows actual fill against the NEC limit (40%).
Need this math wired into a real system? We do that for a living.
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