In structured cabling, the site is wired via the primary cabling. This cabling integrates the subnetworks of a campus that exist in the individual buildings.
The primary cabling covers the area from the main distribution board(HV) to the building distribution boards(GV). At least one distribution board is required per building for connection to the primary network. The ISO/IEC11801 and EN 50173 standards recommend a length of 1,500 m between the main distribution board and the building distribution board for structured cabling.
Generally, multimode fibers with 50/62.5/125 µm are used for off-premise cabling, although monomode fibers with 10/125 µm can also be used, but mainly for very long distances between buildings.
However, the standards also permit symmetrical copper cables for applications with lower transmission speeds, whereby cables with 100 Ohm characteristic impedance ofcategory 3 and 4 are preferred.
The following requirements are placed on off-road cabling:
Bridging of large distances, lightning protection, interference immunity, eavesdropping immunity, future orientation, fail-safety, high availability, maintainability, safe and documented routing, potential separation between building grounds, integration of independent subnetworks of any technology, high transmission capacity, redundant design and alternative routing for emergencies.
In the case of off-road cabling, attention must also be paid to the expandability of the main distribution frames for trouble-free integration of new buildings.