S 5.5 Damage-minimising routing of cables

Initiation responsibility: Building Services, Head of IT, Planner

Implementation responsibility: Building Services

When planning cable trays, it must be ensured that identifiable sources of danger are avoided. In general, cables should only be routed through areas that can be accessed when inside the building. A well-organized cable route design layout facilitates control. Cable trays and individual cables should always be routed in such a way that they are protected against direct damage by personnel, vehicles, and machines.

The locations of devices should be selected in such a way that the cables connected to them are not routed through areas where people walk or vehicles are operated. If this cannot be avoided, the cables must be protected in cable channels suited to handle the expected loads.

In general, sufficient strain relief must be provided for device connection cables plugged into sockets. Sometimes it makes sense not to screw-in the plugs as designed. When the strain on the cable is too high and the plug is not screwed in, only the connection will be torn apart and not the soldered plug/cable or plug/device connections.

Underground car parks pose a major problem in terms of damage-minimising routing of cables. Due to the safety circuits and the fact that entrance gates are open for many hours, access to underground car parks by outsiders can never be ruled out. Because the ceilings are generally low, it is possible to gain access to the cables routed on the ceilings using only simple tools. When cables are routed through traffic areas, the remaining space may be less than the permissible vehicle height. Damage or destruction of the cable trays and cables by vehicles that are too high cannot be ruled out in this case.

When sharing a building with third parties, it must be ensured that no cables are routed through floor, ceiling, or wall channels in the areas occupied by the third parties. All channel systems must be locked mechanically to prevent access from the areas used by the third parties. It is better to terminate them at the border of your own area.

If possible, no cables should be routed through areas subject to a high fire hazard. If this is impossible and the integrity of all cables installed on the tray must be maintained, fire sealing must be provided for the corresponding section of the tray. If the circuit integrity only needs to be maintained for certain cables, an appropriate cable and the corresponding fastening device must be selected to this end. A cable with circuit integrity maintenance cannot fulfil the required function alone. The cable system as a whole must be considered, and this includes the fasteners such as trays, clips, or conduits. It is also important to ensure the cable system cannot be destroyed by parts located above without circuit integrity maintenance when these parts fall down during a fire.

In production plants, high inductive loads and the resulting interference fields are to be expected. These must also be taken account in the cable and tray route layout. To protect the cables, an similar approach is to be take for fire sealing.

For underground cable trays, hazard warning tapes must be placed approx. 10cm above the tray. It is advisable to install cable covers for individual cables (when not in a conduit).

Cables must be routed in such a way that they cannot move during a storm. For example, it should be ensured that any cables routed across exposed roof tops are properly fastened at least every 5 metres. In this connection, it must be taken into account that during a storm, the cables or cable harnesses are subject to powerful forces. Furthermore, cables must be routed so they are protected against mechanical damage, since objects may fall on them. Cables on roof tops or in areas that have louvered walls should therefore always be installed in protective conduits.

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