Conduit support and strap spacing
Every raceway article has a "securing and supporting" section. These are the distances, from the 2023 NEC.
| Raceway | From each box | Then every | Rule |
|---|---|---|---|
| EMT | 3 ft | 10 ft | 358.30 |
| Rigid (RMC) | 3 ft | 10 ft* | 344.30 |
| IMC | 3 ft | 10 ft* | 342.30 |
| FMC (flex) | 12 in | 4-1/2 ft | 348.30 |
| LFMC (liquidtight) | 12 in | 4-1/2 ft | 350.30 |
| PVC | 3 ft | by size, below | 352.30 |
* Straight runs of rigid and IMC with threaded couplings may go further, by size (Table 344.30(B)(2)).
PVC (Table 352.30)
| Trade size | Support every |
|---|---|
| 1/2" to 1" | 3 ft |
| 1-1/4" to 2" | 5 ft |
| 2-1/2" to 3" | 6 ft |
| 3-1/2" to 5" | 7 ft |
| 6" to 6" | 8 ft |
Rigid and IMC, straight runs (Table 344.30(B)(2))
| Trade size | Support every |
|---|---|
| 1/2" to 3/4" | 10 ft |
| 1" to 1" | 12 ft |
| 1-1/4" to 1-1/2" | 14 ft |
| 2" to 2-1/2" | 16 ft |
| 3" to 6" | 20 ft |
The material list counts straps at exactly these distances: one within the end distance of each box, then one at each interval between them. That is the code minimum.