5. Intrabuilding Backbone Pathways

Within a building, the intrabuilding backbone pathways extend between the entrance facilities, equipment room and telecommunications closets. Telecom closets should be stacked vertically above each other on each floor, and provided with a minimum of three 4-inch sleeves (a stub of conduit through the floor) for less than 50,000 square feet served. An equivalent 4" x 12" slot may be used in lieu of three sleeves. Firestopping is required. If closets are not vertically aligned, then 4-inch horizontal conduit runs are required. Include no more than two 90° bends between pull points. Pulling iron or eyes embedded in the concrete for cable pulling is recommended. Fill should not exceed 40 percent for any run greater than two cables.

Backbone and Horizontal Pathways

1. Telco Conduit	6. Vertical Backbone
2. Telco Manhole	7. Telecom Closet
3. Entrance Conduit	8. Horizontal Cabling
4. Telco Entrance Facility	9. Interbuilding Backbone
5. Telcom Equipment Room	10. Electrical Entrance Facility