NEC Chapter 9 Conduit Fill
How Many Wires Fit in 1/2" EMT?
The maximum THHN conductors per wire size in 1/2 inch EMT at the NEC 40% fill limit, with the math and the interactive calculator for any mix of wires.
Max THHN Conductors in 1/2" EMT (40% Fill)
Maximum number of same-size THHN/THWN-2 conductors in 1/2 inch EMT at the NEC Chapter 9 40% fill limit. Count the equipment ground as a conductor.
| Wire Size (THHN) | Max Conductors | Area Each (sq in) |
|---|---|---|
| #14 AWG | 12 | 0.0097 |
| #12 AWG | 9 | 0.0133 |
| #10 AWG | 5 | 0.0211 |
| #8 AWG | 3 | 0.0366 |
| #6 AWG | 2 | 0.0507 |
| #4 AWG | 1 | 0.0824 |
Based on 1/2 inch EMT internal area 0.304 sq in (NEC Chapter 9 Table 4). One conductor allows 53% fill, two allow 31%, three or more allow 40% (Table 1).
Mixed Wire Sizes? Calculate It
The chart is for one wire size at a time. For a real pull with mixed sizes, insulation types, or other conduit, enter your exact conductors for the precise fill percentage.
Frequently Asked Questions
How many wires fit in 1/2 inch EMT?
At the NEC 40% fill limit for three or more conductors, 1/2 inch EMT (internal area 0.304 sq in) holds 9 #12 THHN, 12 #14, 5 #10, or 3 #8 conductors. The math is the conduit area times 0.40 (0.304 × 0.40 = 0.122 sq in allowable), divided by the conductor's area from NEC Chapter 9 Table 5.
How many 12 AWG THHN wires fit in 1/2 inch EMT?
9 #12 THHN conductors fit in 1/2 inch EMT at the 40% fill limit. Each #12 THHN is 0.0133 sq in, so 0.122 sq in allowable ÷ 0.0133 rounds to 9 conductors (NEC Chapter 9 Note 7 rounds up when the decimal is 0.8 or more). The same count applies to THWN-2, which has the identical area.
How many 14 AWG wires fit in 1/2 inch EMT?
12 #14 THHN conductors fit in 1/2 inch EMT at 40% fill. Each #14 THHN is 0.0097 sq in, so 0.122 sq in ÷ 0.0097 rounds to 12 (NEC Chapter 9 Note 7). Remember the ground counts as a conductor, and more than three current-carrying conductors trigger ampacity derating per NEC 310.15(C)(1).
What is the fill limit for 1/2 inch EMT?
The maximum fill depends on how many conductors are in the raceway (NEC Chapter 9, Table 1): 53% for one conductor, 31% for two, and 40% for three or more. For 1/2 inch EMT that is 0.161 sq in for one wire, 0.094 sq in for two, and 0.122 sq in for three or more. The 40% case is the common one.
Fill for Other Conduit Sizes
Wires in 3/4" EMT
16 #12 THHN and the full count for 3/4 inch pipe.
Wires in 1" EMT
26 #12 THHN and the full count for 1 inch pipe.
Wires in 1-1/4" EMT
45 #12 THHN and the full count for 1-1/4 inch pipe.
Wires in 2" EMT
101 #12 THHN and the full count for 2 inch pipe.
Conduit Fill Chart (all sizes)
Max THHN per EMT size from #14 to 500 kcmil in one table.
Conduit Bending Calculator
Marks for offsets, saddles, 90s, and kicks with SVG diagrams.
Fill checks out. Will the wire reach?
Getting the conductors in the pipe is one thing. Confirm the gauge holds up over distance with the voltage drop calculator before you pull.