Width (one layer, a diameter apart)
W = (Σ D + Σ gaps) × (1 + spare) → the next standard width
- D = each cable’s outer diameter
- gaps = one diameter between neighbours (the smaller cables’)
- spare = 25 % by default; never under the minimum width
STANDARDS & FORMULAS
Cable Tray
Cable tray routed along your lines and sized from the real cables it carries, with its sections.
Standards and regulations
- IEC 60364-5-52Low-voltage installations - wiring systems
The default: one layer, a diameter’s gap between neighbours (reference method F: the cables keep their full rating).
- NEC 392.22Cable trays - number of conductors (fill)
The “by area” option: the cables’ areas within a percentage of the tray’s (50 % by default).
Formulas
Width (by area)
W = Σ (π D² / 4) / (H × fill limit)
- H = the tray’s height
Fill
by width = Σ D / W · by area = Σ (π D² / 4) / (W × H)
Design rules it applies
- The width drops by itself after each branch
- Dipped under the beams it would hit
For reference. MO.tool works these out to help your design; the engineer remains responsible for it. Always check the edition of each standard your project uses and the requirements of the local authority (DEWA, ADDC, Civil Defence…).