The minimal bend radius of wiring conduits KOPOS is expressed in millimetres and relates to the inner central axis of the tube (see the figure).
| Nominal dimension | Minimal bend radius (mm) | |
| EN | ČSN | |
| 16 | 60 | |
| 13,5 | 70 | |
| 20 | 80 | |
| 16 | 80 | |
| 25 | 100 | |
| 23 | 100 | |
| 32 | 120 | |
| 29 | 140 | |
| 40 | 170 | |
| 36 | 200 | |
| 50 | 220 | |
| 48 | 250 | |
| 63 | 250 | |