How many wires can I run through a 2 inch EMT conduit?

The raw number is 138. Two inch EMT has a total internal area of 3.356 square inches per Chapter 9, Table 4 of the NEC 2023. For more than two conductors the permitted fill is 40 percent, which gives 1.342 square inches of usable area. A 14 AWG THHN conductor takes 0.0097 square inches per Chapter 9, Table 5. Divide and you get 138 conductors. Annex C, Table C.1 lists the same figure for a pull of all one size, and that table is what most inspectors reach for first.

That number is almost never the number you should actually pull.

Why 138 is a paper answer

Section 310.15(C)(1) requires ampacity adjustment when more than three current carrying conductors run in the same raceway for more than 24 inches. The factors are 80 percent for 4 to 6 conductors, 70 percent for 7 to 9, 50 percent for 10 to 20, 45 percent for 21 to 30, 40 percent for 31 to 40, and 35 percent for 41 and above. A 14 AWG THHN conductor starts at 25 amps in the 90 degree C column of Table 310.16. At 35 percent that drops to 8.75 amps, well under what a 15 amp breaker needs.

Neutrals on a balanced three phase four wire wye circuit are not counted as current carrying under 310.15(E)(1), and equipment grounding conductors are never counted under 310.15(E)(3). Neutrals on a single phase three wire circuit that carry only the unbalanced load are also not counted. So a raceway with a lot of shared neutrals derates better than one full of individual circuits.

The practical ceiling

For 15 amp lighting circuits on 14 AWG THHN, nine current carrying conductors is the usual stopping point, because the 70 percent factor leaves 17.5 amps. Push to ten and the 50 percent factor gives 12.5 amps and the circuit no longer supports a 15 amp breaker. Contractors who need more circuits in one pipe usually move up to 12 AWG, which starts at 30 amps and survives a 50 percent factor at 15 amps.

Do not forget the bends

Section 358.26 limits the run between pull points to a total of 360 degrees of bend. Four 90 degree bends and you are done, no matter how much room is left inside the pipe. On a long two inch run packed near capacity, add pull boxes sized under 314.28 rather than fighting the pull.

Field takeaway

Two inch EMT will physically hold 138 14 AWG conductors. Derating under 310.15(C)(1) caps a real 15 amp install near nine current carrying conductors. Size the pipe for the circuits you need after adjustment, not for the fill table.