Backbone pathways provide paths for backbone cabling between the equipment room, telecommunications rooms, main-terminal space, and entrance facility. The TIA suggests in TIA-569-B that the telecommunications rooms be stacked on top of one another from floor to floor so that cables can be routed straight up through a riser. They also recommend pathway diversity and redundancy. ANSI/TIA-568-C defines a few types of backbone pathways:
Ceiling pathways These pathways allow the cable to be run loosely through the ceiling space.Conduit pathways Conduit pathways have the cable installed in a metallic or plastic conduit.Tray pathways These are the same types of trays used for horizontal cabling.
| KEY TERM: sleeves, slots, and cores | Sleeves are circular openings that are cut in walls, ceilings, and floors; a slot is the same but rectangular in shape. A coreis a circular hole that is cut in a floor or ceiling and is used to access the floor above or below. Cores, slots, and sleeves cut through a floor, ceiling, or wall designed as a firestopping wall must have firestopping material inserted in the hole after the cable is installed through it. |
Some points to consider when designing backbone pathways include the following:
- Intercloset conduit must be 78(3) trade size (3″ or 78 mm sleeve).
- Backbone conduit must be 103(4) trade size (4″ or 103 mm sleeve).
- Firestopping material must be installed where a backbone cable penetrates a firewall (a wall designed to stop or hinder fire).
- Trays, conduits, sleeves, and slots need to penetrate at least 1″ (25 mm) into telecommunication rooms and equipment rooms.
- Backbone cables should be grounded per local code, the NEC, and ANSI/TIA-607-B.
- Backbone pathways should be dry and not susceptible to water penetration.
| Warning | Devices such as cable trays, conduit, and hangers must meet requirements of the NEC with regard to their placement. For example, flexible-metal conduit is not allowed in plenum spaces except under restricted circumstances. |
