EMT conduit fill check
Percent fill of an EMT conduit for a number of THHN conductors against the NEC 40% rule.
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- Your own numbers, worked out as often as you like
- The full run sheet you can print or save to My work
- 3 cited sources, linked, with the checks to make
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- A plain-words read of your result (a fuller AI read with the Bifrost AI add-on)
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Example result · fictional numbers
What you get: run sheet
Worked out by this tool from its default inputs. Its role plan lets you run your own numbers, print the sheet and save it.
9 × 12 AWG in 3/4 in EMT: 22.5% fill (OK), 20.0 A each after derating, no pull point to add for 270° of bends
- Conductor area
- 0.1197 sq in
- Conduit fill
- 22.5% of 40% allowed (OK)
- Max 12 AWG in this conduit
- 16
- Smallest EMT that works
- 1/2 in
Fill and conductor rating
- Fill
- 22.5% of the 40% allowed in 3/4 in EMT: OK
- Most 12 AWG in 3/4 in
- 16 conductors; check against Annex C
- Current-carrying conductors
- 6: adjustment 80%
- Ambient
- Up to 86 °F (30 °C): correction 100%
- Each conductor can carry
- 24.0 A from the 90 °C column (30 A × 0.80 × 1.00), no more than 25 A at 75 °C terminals and a 20 A breaker (240.4(D)): 20.0 A
Also on the sheet
- Pulling and support · 3 lines, starting with “Bends”
- Material list · 4 lines, starting with “EMT”
The plain-words read of this example
9 × 12 AWG THHN fill 3/4 in EMT to 22.5% against the 40% limit, so it fits. With 6 current-carrying conductors and air up to 86 °F (30 °C), each conductor is good for 20.0 A. The 270° of bends fit in one pull, and the 120 ft run needs 13 straps. Order 12 sticks of EMT and 1,153 ft of wire, about $309.54 before fittings.
3 cited sources
- NFPA 70, National Electrical Code (NEC) (National Fire Protection Association)
- NEC Chapter 9 (Tables 1, 4 and 5) and Informative Annex C (NFPA free access (read-only, free account))
- Stumped by the Code? NEC Requirements for Using and Installing EMT (EC&M)
Plus 5 step-by-step checks, a print layout and a link that reopens it with your numbers.