The Definition of Backbone Cabling

Backbone cabling may be within one building or between buildings on a campus. All wiring between telecommunication rooms is called as backbone cabling.

In many cases, backbone cabling is actually between wiring closets on the same floor of a building, but the more typical case is the floor to floor wiring in a multi-floor building. Many call it vertical cabling in contrast to horizontal cabling.

:: How are backbone wiring implemented?

Typically all hubs, concentrators and switches are placed in the telecom rooms which serve all workstations on that same floor. Backbone wiring then connects the hubs, on to another on different floors.

• Daisy Chain wiring. In a daisy chain wiring, the back bone wiring connects from hub to hub to hub. Daisy chain is a good choice for Token-Ring topology, since it provides convenient ring-in and ring-out connections.

• Star wiring: In a star wiring, the back bone wiring connects all hubs from different floors to a center hub. Star wiring is a good choice for Ethernet which must limits repeater jumps.

For large buildings, telecom rooms are often placed in services shaft, one above the other, distances between telecom rooms are minimal. Thus the backbone wiring from each floor may be concentrated in a single master telecom room and the number of repeater jumps minimized.

:: How is backbone wiring capacity implemented?

Backbone wiring should be terminated in the same manner as horizontal cabling. The backbone cabling should be of same or higher category and type that meets your performance requirements and the safety and fire protection requirements for your installation.

For example, for Cat 5e horizontal wiring, you should use Cat 5e cable or even higher category such as Cat 6 and Cat 7. If you anticipate using your wiring system for multiple applications, double or even triple each backbone wiring run. This will give you ample room for growth and the ability to rapidly respond to new requirements.

:: Fire Safety

Most standard require that all riser cable (cable that goes vertically between floors) be riser rated for its fire and smoking rating. Some even require plenum rated cables.

But one most important thing is - you must properly install fire-stop material on all openings you make between floors, no matter those are cable ports or direct openings.

If you backbone wiring actually involves floor-to-floor cabling in vertical shafts or cable ports, you may need to use special riser cable that has a fire-retardant sheath, certified to meet NEC low-flame requirements. The NEC requires that riser cable meet UL flammability tests to be used in high-rise buildings.

:: Grounding requirement

When pulling cables between far flung telecom rooms or between floors, electrical grounding and bonding requirements must be observed. You can refer to EIA/TIA standards for the proper practices.

:: Advantages of fiber optic cable

Fiber optic cable provides significant advantages over copper cable. Fiber optic cable is not subject to electrical or magnetic interference, and thus may be run in locations, such as elevator shafts or alongside power lines.