Containment decides how a cable is supported, protected and cooled for the whole of its life, so the choice affects current rating, cost and maintenance. The table compares the common options for industrial power and control cables.
| Containment | Best suited to | Strengths | Points to watch |
|---|---|---|---|
| Ladder tray | Long indoor and outdoor runs carrying heavy power cables | Open construction gives good air circulation. Easy to add or remove cables. | Cables are exposed to mechanical damage and sunlight unless covered. Fix cables at regular intervals along the run. |
| Perforated tray | Mixed power and control cables inside plants | Continuous support under the cable. Good ventilation through the perforations. | Segregate power from signal cables with barriers or separate trays. |
| Conduit | Short runs, drops to equipment, and cables needing mechanical protection | Strong protection against impact and rodents. Neat appearance. | Poor heat dissipation, so the current rating usually falls. Pulling is harder over long runs with bends. |
| Trunking | Indoor panels, offices and light industrial areas | Tidy, enclosed route that is easy to open for changes. | Fill ratio must be respected, and many cables in one trunking need derating. |
| Cable trench | Substations, switchrooms and plant floors | Protected route with room for many cables, and covers allow access. | Needs drainage. Water and dirt entry must be controlled. |
| Direct burial | Long outdoor runs between buildings and across sites | Low installation cost and good heat dissipation in suitable soil. | Needs correct depth, bedding and warning tape. Repairs mean excavation. |
| Buried duct or pipe | Road crossings and routes where cables may be replaced | Cable can be withdrawn and replaced without digging. | Heat dissipation is lower than direct burial. Use a duct size that suits the cable diameter. |
How the choice affects current rating
Rating tables assume a stated installation method. Moving a cable from open tray to conduit, or adding more cables to the same tray, lowers the current it can carry. The correction factors are given in the cable derating factors chart. Tray width and fill are covered in the cable tray sizing and fill guide, and buried installations in the underground cable laying guide.
Matching the cable to the route
Armoured cables suit direct burial and exposed tray runs where mechanical damage is possible. Unarmoured cables suit protected routes such as conduit and trunking. The armour options are compared in the cable armouring guide, and the cables are listed on the LV XLPE power cables page, available armoured or unarmoured.