Conduit fill Chart
While conduit fill can be calculated mathematically, this conduit fill chart simplifies the process of determining how many wires rigid conduit can safely hold according to the 2023 National Electrical Code. The column headings denote the trade size/metric designator of conduit while the row headings on the left specify the type of wire and the conductor size (American Gauge Wire). The result, at the intersection of trade size and wire type, indicates the maximum allowable number of wires for each conduit size.
Maximum Number of Conductors or Fixture Wires in Rigid Metal Conduit (RMC)
Download Conduit Fill Chart| Type | Conductor
. Size . (AWG/ . kcmil) | Trade Size (Metric Designator) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 3⁄8
. (12) |
1⁄2
. (16) |
3⁄4
. (21) |
1
. (27) |
11⁄4
. (35) |
11⁄2
. (41) |
2
. (53) |
21⁄2
. (63) |
3
. (78) |
31⁄2
. (91) |
4
. (103) |
5
. (129) |
6
. (155) |
||||
| Conductors | ||||||||||||||||
| THHN, THWN, THWN-2 | 14 | — | 13 | 22 | 36 | 63 | 85 | 140 | 200 | 309 | 412 | 531 | 833 | 1202 | ||
| 12 | — | 9 | 16 | 26 | 46 | 62 | 102 | 146 | 225 | 301 | 387 | 608 | 877 | |||
| 10 | — | 6 | 10 | 17 | 29 | 39 | 64 | 92 | 142 | 189 | 244 | 383 | 552 | |||
| 8 | — | 3 | 6 | 9 | 16 | 22 | 37 | 53 | 82 | 109 | 140 | 221 | 318 | |||
| 6 | — | 2 | 4 | 7 | 12 | 16 | 27 | 38 | 59 | 79 | 101 | 159 | 230 | |||
| 4 | — | 1 | 2 | 4 | 7 | 10 | 16 | 23 | 36 | 48 | 62 | 98 | 141 | |||
| 3 | — | 1 | 1 | 3 | 6 | 8 | 14 | 20 | 31 | 41 | 53 | 83 | 120 | |||
| 2 | — | 1 | 1 | 3 | 5 | 7 | 11 | 17 | 26 | 34 | 44 | 70 | 100 | |||
| 1 | — | 1 | 1 | 1 | 4 | 5 | 8 | 12 | 19 | 25 | 33 | 51 | 74 | |||
| 1/0 | — | 1 | 1 | 1 | 3 | 4 | 7 | 10 | 16 | 21 | 27 | 43 | 63 | |||
| 2/0 | — | 0 | 1 | 1 | 2 | 3 | 6 | 8 | 13 | 18 | 23 | 36 | 52 | |||
| 3/0 | — | 0 | 1 | 1 | 1 | 3 | 5 | 7 | 11 | 15 | 19 | 30 | 43 | |||
| 4/0 | — | 0 | 1 | 1 | 1 | 2 | 4 | 6 | 9 | 12 | 16 | 25 | 36 | |||
| 250 | — | 0 | 0 | 1 | 1 | 1 | 3 | 5 | 7 | 10 | 13 | 20 | 29 | |||
| 300 | — | 0 | 0 | 1 | 1 | 1 | 3 | 4 | 6 | 8 | 11 | 17 | 25 | |||
| 350 | — | 0 | 0 | 1 | 1 | 1 | 2 | 3 | 5 | 7 | 10 | 15 | 22 | |||
| 400 | — | 0 | 0 | 1 | 1 | 1 | 2 | 3 | 5 | 7 | 8 | 13 | 20 | |||
| 500 | 0 | 0 | 0 | 1 | 1 | 1 | 2 | 4 | 5 | 7 | 11 | 16 | ||||
| 600 | — | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 3 | 4 | 6 | 9 | 13 | |||
| 700 | — | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 3 | 4 | 5 | 8 | 11 | |||
| 750 | — | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 3 | 4 | 5 | 7 | 11 | |||
| 800 | — | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 2 | 3 | 4 | 7 | 10 | |||
| 900 | — | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 2 | 3 | 4 | 6 | 9 | |||
| 1000 | — | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 3 | 4 | 6 | 8 | |||
Notes:
This table is for concentric stranded conductors only. For compact stranded conductors, Table C.8(A) should be used.
Reproduced with permission of NFPA from NFPA 70®, National Electrical Code®, 2023 edition. Copyright© 2022, National Fire Protection Association. For a full copy of the NFPA 70®, please go to www.nfpa.org.
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