Telecommunications Cabling and Electronics Specifications Guidelines

Contact: Ron Olton

Backbone Raceways

Backbone raceways are a series of accesses that connect ENTRANCE WIRING CLOSETS to FLOOR WIRING CLOSETS. The term backbone has replaced riser and house in cable terminology.

GENERAL:

Backbone raceways may be slots or sleeves between floors or they may consist of conduits or trays and racks in which cables may be routed for support and protection.

DESIGN:

When WIRING CLOSETS are located above each other, sleeves or slots may be used. When they are so situated, conduits should be utilized to provide security and physical protection to the cables.

SIZE:

The size of sleeves or conduits can be stated as one since sleeves will probably be made of pieces of conduit placed through the floor. A minimum of 4-inch conduits should be used. If space limitations prevent the use of 4-inch conduits then the number of 3-inch ducts provided should be doubled or if 2-inch ducts are used the number should be increased four fold. Slots should be a minimum of 4-inches inside dimension square. Slot sizes and/or numbers of slots can be determined by the number of 4-inch conduits or sleeves required under Table 5-1.

(*) does not include two spare ducts or sleeves

QUANTITY:

A minimum of one 4-inch conduit or sleeve should be provided per FWC plus two spares. If higher floors FWC’s are supplied from lower floor FWC’s (as with sleeves or slots) only one conduit for every two rooms need to be added to the backbone. See Figure 5-1.

SEALS:

All conduits should be provided with seals until used to prevent the entrance of gases. Sleeves and slots should be sealed with firestop material to prevent the spread of fire.

                              FIGURE 5-1

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