This document specifies design principles for information technology and network telecommunications cabling (e.g. SAN and LAN) in accordance with EN 50173-5, based upon the criteria and classifications for availability and physical security within EN 50600-1. This document addresses the telecommunications cabling infrastructures used in data centres. It describes: a) for design, the application of generic cabling standards in the EN 50173 series; b) for installation specification, planning and practices and quality assurance, the application of standards in the EN 50174 series (and related standards). In addition, this document specifies requirements and recommendations for the following: 1) general information technology cabling to support the IT operation of the data centre; 2) telecommunications cabling to monitor and control, as appropriate, power distribution, environmental control and physical security of the data centre; 3) other building automation cabling; 4) pathways, pathway systems, spaces and enclosures for the telecommunications cabling infrastructures. Safety and electromagnetic compatibility (EMC) requirements are outside the scope of this document and are covered by other standards and regulations. However, information given in this document can be of assistance in meeting these standards and regulations.