Wire Duct and Trunking Sizing
Wire duct and trunking sizing determines the width, height, and fill capacity of the slotted plastic wireway used to route internal panel wiring between terminal blocks, PLC racks, and drives. Getting the duct fill ratio right keeps wiring accessible for troubleshooting, leaves room for future additions, and avoids trapping heat against densely packed cables.
- Routing internal control wiring between terminal strips, PLC I/O, and drive terminals.
- Separating power and signal wiring into physically distinct duct runs to reduce noise coupling.
- Providing accessible wire routing that can be opened and modified without full panel rewiring.
- Sizing duct capacity to accommodate spare terminal points added during commissioning.
Duct sizing is based on a target fill ratio — commonly around 40–60% of the duct's cross-sectional area — calculated from the total cross-sectional area of all conductors expected to run through that section, including spares. Running ducts at too high a fill ratio makes future wiring changes difficult and can trap heat in power wiring sections; running at too low a fill ratio wastes panel space. Power and signal wiring are typically routed in separate ducts, or with a physical divider, to limit electromagnetic coupling between noisy VFD/servo cabling and sensitive analog or communication wiring.
- Sizing duct based only on the initial wire count with no allowance for spares or future additions.
- Routing high-noise VFD output wiring in the same duct as analog signal or communication cabling.
- Overfilling ducts to the point where the cover cannot close properly or wires cannot be added without a full re-route.
- Ignoring heat buildup in ducts carrying multiple high-current power conductors bundled tightly together.
- Choosing duct width based on panel space alone without calculating actual conductor cross-sectional fill.
ClusterVise estimates duct fill directly from the generated wiring list and conductor sizes, keeping power and signal routing recommendations separated automatically, so panel layout avoids overfilled ducts or noise-coupling issues discovered only during commissioning.
| Item | Selection | Basis |
|---|---|---|
| Conductor count (this run) | 42 wires, mixed 0.5–2.5mm² | Includes 8 spare positions for future I/O |
| Calculated fill area | 48% of duct cross-section | Within target 40–60% fill ratio range |
| Selected duct size | 60mm x 60mm slotted duct | Meets fill target with room for cover closure |
| Routing separation | Separate duct for VFD output cabling | Limits EMC coupling into signal wiring |
| Spare capacity | 12% additional fill room reserved | Accommodates future terminal additions |
