WireWicket / NEC lookup
Derived answer · NFPA 70 (NEC) 2026
How many 12 AWG THHN/THWN-2 conductors fit in 1-inch EMT?
For repeated 12 AWG THHN/THWN-2 conductors in 1-inch EMT, the supported NEC 2026 calculation gives a maximum of 25 conductors.
Static answer
25 conductors
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Assumptions
- All conductors are identical 12 AWG THHN/THWN-2 conductors using the supported Table 5 area of 0.0133 in².
- The raceway is EMT at the listed trade size, using its internal area from the supported Table 4 data.
- The count includes only the identical conductors in the query; separately sized grounding, neutral, or other conductors are not added.
- The count is evaluated under Chapter 9 Table 1 fill limits; conductor arrangement, installation conditions, and local amendments are outside this lookup.
Method
Chapter 9 Table 5 gives 0.0133 in² per conductor. For three or more conductors, Table 1 permits 40% of the 1-inch EMT area (0.8640 in²), or 0.3456 in². At 25 conductors, the total is 0.3325 in²; the next count (26) would use 0.3458 in² and exceed the permitted area.
Edition and source
NFPA 70 (NEC) 2026. Chapter 9, Table 1 (permitted fill); Table 4 (EMT raceway area); Table 5 (THHN / THWN-2 conductor area). Article 358 (EMT). View NFPA 70 (2026) in NFPA LiNK
Verify the edition adopted by your jurisdiction and any local amendments. This reference tool does not replace project review or AHJ requirements.
This page provides one derived calculation only; it does not reproduce the source tables.
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Raceway-fill maximum calculator
Choose supported conductor and raceway values to find the highest count that passes the same NEC fill calculation used by WireWicket’s raceway calculator.
Calculated maximum
25 conductors
- Conductor area each
- 0.0133 in²
- Total conductor area
- 0.3325 in²
- Allowable area
- 0.3456 in² (40%)
- Actual raceway fill
- 38.48%
The next count, 26, uses 0.3458 in² and exceeds its 0.3456 in² permitted area.
NFPA 70 (NEC) 2026; Chapter 9, Table 1 (permitted fill); Table 4 (EMT raceway area); Table 5 (THHN / THWN-2 conductor area). Article 358 (EMT). View NFPA 70 (2026) in NFPA LiNK
Verify the edition adopted by your jurisdiction and any local amendments. This reference tool does not replace project review or AHJ requirements.