S 1.20 Selection of cable types suited in terms of their physical/mechanical properties

Initiation responsibility: Planner, IT Security Officer, Head of IT, Building Services Manager

Implementation responsibility: Building Services, Head of IT

When selecting cables, technical transmission requirements as well as the environment the cables will be routed through and operated in must be taken into account. To meet this wide variety of requirements, cable manufacturers offer different types of cables on the market or develop corresponding solutions.

The following criteria must be taken into account in terms of the cable sheathing when routed inside or outside:

• temperature
• surrounding medium (water, waste water, acids, gas, light)
• rodent protection, impact and shovel penetration resistance, falling rock impact resistance, water pressure resistance
• maintenance of circuit integrity in areas exposed to fire hazards
• special pulling forces arising through the use of overhead lines, for example

Furthermore, the tray systems planned for use such as cable platforms, cable ladders, cable channels, cable conduits, moulded bricks for cables, tray sections, and overhead line constructions must also be taken into account.

The following cable design factors must be taken into account as well:

• pulling forces arising from installing cable using machines, e.g. from cable draw winches or cable blower systems, or from manual installation
• bending radius and lateral pressure stability according to the installation method and final resting state during operation
• water-blocking protection for damp or wet areas
• special pulling forces in the installed state that arise from large span lengths or securing distances when overhead lines are used or from extremely steep rises
• strong electrical and inductive interference fields using shielded cables

The proper selection of electrical cables in accordance with the regulations and compliance with the relevant standards and regulations (DIN VDE 0100 "Erection of power installations with rated voltages up to 1000 V", DIN 4102 "Fire behaviour of building materials and elements") and the generally accepted state of the art form the foundation of contingency planning for the electrical installation.

The individual requirements for the selection of cables may not be defined by the IT department alone, especially for operating environments in which environmental influences or special structural situations must be taken into account. In particular, employees in Building Services, who are familiar with the operating procedures and other special conditions, must participate in the determination of the relevant influences on the planned cable route, and therefore in the determination of the special requirements placed on the cable design.

Review questions:

• When selecting cables, were the technical transmission requirements as well as the environment the cables will be routed through and operated in taken into account?
• Were the necessary criteria taken into account in terms of the cable sheathing (e.g.: temperature range, maintenance of circuit integrity, water pressure resistance, etc.)?
• Are the applicable standards and regulations (e.g. for fire protection, operational safety) observed when selecting the electric cables?