Conduit / Tray Fill Selection
Compute the required conduit inner diameter from cable outer diameter, count, and bends; recommend a standard size and check actual fill and cable count.
Key points
Conduit / Tray Fill Selection: Compute the required conduit inner diameter from cable outer diameter, count, and bends; recommend a standard size and check actual fill and cable count. Formula: A_cable = n·πd²/4 | A_req = A_cable/fill | D_req = √(4A_req/π). Enter parameters on the DD-CAT IDE online tool page to get results instantly, with a calculation-model diagram that updates with the inputs. Conduit fill uses total cable outer-diameter area, not conductor cross-section; multi-core cables use the overall diameter. More bends and longer runs make pulling harder; practice often reduces fill by another 5–10% and adds pull boxes.
Inputs
A_cable = n·πd²/4 | A_req = A_cable/fill | D_req = √(4A_req/π)Calculation model (updates with parameters)
| Allowed fill ratio | 40 % | 基准 40%, by弯头折减 |
| Total cable area | 314.2 mm² | n×πd²/4（按电缆外径，不是导体Cross-section） |
| Required conduit inner diameter | 31.6 mm | 按填充率反算 |
| Recommended standard conduit | DN32 | 按常用 PVC / 钢导管档bits向上取整 |
| Actual fill ratio | 39.1 % | 需 ≤ 40% |
| Maximum cables in this conduit | 4 根 | 按外径 10.0 mm、填充率 40% |
| Selection result | 通过 ✓ | met填充率要求 |
Engineering notes
- Conduit fill uses total cable outer-diameter area, not conductor cross-section; multi-core cables use the overall diameter.
- More bends and longer runs make pulling harder; practice often reduces fill by another 5–10% and adds pull boxes.
- Tray fill is usually checked by area / width; power and signal cables should be layered to avoid interference and concentrated heating.
FAQ
- What is Conduit / Tray Fill Selection for?
- Compute the required conduit inner diameter from cable outer diameter, count, and bends; recommend a standard size and check actual fill and cable count.
- What is the formula for Conduit / Tray Fill Selection?
- Core formula: A_cable = n·πd²/4 | A_req = A_cable/fill | D_req = √(4A_req/π). The tool returns results instantly using this formula and the selected parameters.
- What engineering notes should I keep in mind when using Conduit / Tray Fill Selection?
- Conduit fill uses total cable outer-diameter area, not conductor cross-section; multi-core cables use the overall diameter. More bends and longer runs make pulling harder; practice often reduces fill by another 5–10% and adds pull boxes. Tray fill is usually checked by area / width; power and signal cables should be layered to avoid interference and concentrated heating.