DEMO — fictional range. Local brief only, NOT SENT. No personal data is collected or transmitted.
LOAD
Wind acts on the parts nobody designed for it.
A tray run and an enclosure are both exposed surfaces. The load case is not the weight of the equipment but what the wind does to the shape of it.
- Dead load
- The enclosure, the tray, the cable and the equipment · rarely the governing case
- Wind uplift
- On a roof, the pressure on the underside of a tray run and an enclosure lid
- Wind lateral
- On the face of an enclosure mounted at height, which the wall fixings carry
- Cable load
- The weight of a full tray, which is often more than the tray was sized for
- Thermal
- Expansion of a long tray run, which moves the fixings
- Maintenance load
- A person standing on the tray or leaning on the enclosure
Illustrative load record
| Case | Comes from | What it decides |
|---|---|---|
| Cable load | Cable weight at the declared fill | Support centres and tray span |
| Wind uplift | Regional speed, height, roof zone | Fixing centres on the tray and the enclosure |
| Wind lateral | Face area and height above ground | Wall fixing type and count |
| Thermal movement | Run length and daily range | Whether the run is fixed or floating |
Why cable load is usually the governing case.
Because a tray is sized when it is empty. A full tray of cable weighs far more, and the installer who fills it to capacity has loaded a part that was selected for its dimensions.
The question worth asking instead.
What the tray span is at the declared cable fill, not empty. A supplier who can answer that has sized the part for its use rather than for its appearance on a drawing.