Conduit Fill
Maximum conductor counts for EMT, RMC, and PVC conduit with fill percentage rules.
4 reference items · 4 sections
EMT (Electrical Metallic Tubing)
Max THHN/THWN Conductors in EMT
NEC Chapter 9, Table 4 Conduit Fill Calculator
Maximum Number of THHN/THWN Conductors in EMT
| AWG | ½" | ¾" | 1" | 1¼" | 1½" | 2" | 2½" | 3" | 4" |
|---|---|---|---|---|---|---|---|---|---|
| 14 | 12 | 22 | 35 | 61 | 84 | 138 | — | — | — |
| 12 | 9 | 16 | 26 | 45 | 61 | 101 | — | — | — |
| 10 | 5 | 10 | 16 | 28 | 38 | 63 | 99 | 154 | 239 |
| 8 | 3 | 6 | 9 | 16 | 22 | 36 | 57 | 88 | 137 |
| 6 | 2 | 4 | 7 | 12 | 16 | 26 | 41 | 64 | 99 |
| 4 | 1 | 2 | 4 | 7 | 10 | 16 | 25 | 39 | 60 |
| 3 | 1 | 2 | 4 | 6 | 8 | 14 | 22 | 33 | 52 |
| 2 | 1 | 1 | 3 | 5 | 7 | 12 | 18 | 29 | 44 |
| 1 | 1 | 1 | 2 | 4 | 5 | 8 | 13 | 20 | 32 |
| 1/0 | 0 | 1 | 1 | 3 | 4 | 7 | 11 | 17 | 27 |
| 2/0 | 0 | 1 | 1 | 3 | 4 | 6 | 10 | 15 | 23 |
| 3/0 | 0 | 1 | 1 | 2 | 3 | 5 | 8 | 12 | 19 |
| 4/0 | 0 | 1 | 1 | 1 | 3 | 4 | 7 | 10 | 16 |
| 250 | 0 | 0 | 1 | 1 | 2 | 3 | 5 | 8 | 13 |
| 300 | 0 | 0 | 1 | 1 | 1 | 3 | 5 | 7 | 11 |
| 350 | 0 | 0 | 1 | 1 | 1 | 3 | 4 | 7 | 10 |
| 400 | 0 | 0 | 0 | 1 | 1 | 2 | 4 | 6 | 9 |
| 500 | 0 | 0 | 0 | 1 | 1 | 1 | 3 | 5 | 7 |
1.Based on NEC Chapter 9, Tables 4 & 5
2.0 = conductor too large for this conduit size
3.— = not typically needed for this wire size
RMC (Rigid Metal Conduit)
Max THHN/THWN Conductors in RMC
NEC Chapter 9, Table 4
Maximum Number of THHN/THWN Conductors in RMC
| AWG | ½" | ¾" | 1" | 1¼" | 1½" | 2" | 2½" | 3" | 4" |
|---|---|---|---|---|---|---|---|---|---|
| 14 | 10 | 18 | 29 | 51 | 70 | 116 | 169 | 261 | 407 |
| 12 | 7 | 13 | 22 | 38 | 51 | 85 | 124 | 191 | 298 |
| 10 | 5 | 8 | 13 | 24 | 32 | 53 | 78 | 120 | 187 |
| 8 | 3 | 5 | 8 | 13 | 18 | 30 | 44 | 69 | 107 |
| 6 | 1 | 3 | 5 | 10 | 13 | 22 | 32 | 50 | 78 |
| 4 | 1 | 2 | 4 | 6 | 8 | 13 | 20 | 30 | 48 |
| 3 | 1 | 1 | 3 | 5 | 7 | 12 | 17 | 26 | 41 |
| 2 | 1 | 1 | 3 | 4 | 6 | 10 | 14 | 22 | 35 |
| 1 | 0 | 1 | 1 | 3 | 4 | 7 | 10 | 16 | 25 |
| 1/0 | 0 | 1 | 1 | 3 | 4 | 6 | 9 | 14 | 22 |
| 2/0 | 0 | 1 | 1 | 2 | 3 | 5 | 7 | 11 | 18 |
| 3/0 | 0 | 1 | 1 | 1 | 3 | 4 | 6 | 10 | 15 |
| 4/0 | 0 | 0 | 1 | 1 | 2 | 4 | 5 | 8 | 13 |
| 250 | 0 | 0 | 1 | 1 | 1 | 3 | 4 | 7 | 11 |
| 300 | 0 | 0 | 0 | 1 | 1 | 2 | 4 | 6 | 9 |
| 350 | 0 | 0 | 0 | 1 | 1 | 2 | 3 | 5 | 8 |
| 400 | 0 | 0 | 0 | 1 | 1 | 1 | 3 | 5 | 7 |
| 500 | 0 | 0 | 0 | 1 | 1 | 1 | 2 | 4 | 6 |
1.Based on NEC Chapter 9, Tables 4 & 5
2.RMC has slightly smaller internal diameter than EMT
PVC Conduit (Schedule 40)
Max THHN/THWN Conductors in PVC Sch. 40
NEC Chapter 9, Table 4
Maximum Number of THHN/THWN Conductors in PVC Schedule 40
| AWG | ½" | ¾" | 1" | 1¼" | 1½" | 2" | 2½" | 3" | 4" |
|---|---|---|---|---|---|---|---|---|---|
| 14 | 11 | 21 | 34 | 60 | 82 | 135 | 190 | 297 | 464 |
| 12 | 8 | 15 | 25 | 44 | 60 | 99 | 139 | 217 | 339 |
| 10 | 5 | 10 | 16 | 28 | 38 | 62 | 88 | 137 | 214 |
| 8 | 3 | 5 | 9 | 16 | 21 | 35 | 50 | 78 | 122 |
| 6 | 2 | 4 | 6 | 11 | 15 | 26 | 36 | 56 | 88 |
| 4 | 1 | 2 | 4 | 7 | 10 | 16 | 22 | 35 | 54 |
| 3 | 1 | 2 | 3 | 6 | 8 | 13 | 19 | 30 | 47 |
| 2 | 1 | 1 | 3 | 5 | 7 | 11 | 16 | 25 | 40 |
| 1 | 0 | 1 | 2 | 3 | 5 | 8 | 11 | 18 | 28 |
| 1/0 | 0 | 1 | 1 | 3 | 4 | 7 | 10 | 15 | 24 |
| 2/0 | 0 | 1 | 1 | 2 | 3 | 6 | 8 | 13 | 20 |
| 3/0 | 0 | 1 | 1 | 2 | 3 | 5 | 7 | 11 | 17 |
| 4/0 | 0 | 0 | 1 | 1 | 2 | 4 | 6 | 9 | 14 |
1.Schedule 40 PVC — most common for general wiring
2.Schedule 80 PVC has thicker walls (less fill area)
Conduit Fill Rules
Maximum Conduit Fill Percentages
NEC Chapter 9, Table 1
Maximum Percent Fill of Conduit/Tubing
| Number of Conductors | Max % Fill |
|---|---|
| 1 conductor | 53% |
| 2 conductors | 31% |
| 3 or more | 40% |
These percentages apply to the total cross-sectional area of the conduit's internal diameter. Nipples (≤ 24 inches) are allowed 60% fill.
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