Wiring Closets and Intermediate Distribution Facilities

• Rooms must be secured • Environmental protections for the cable against unauthorized plant and or wiring closet

access

• Access to rooms should be monitored/recorded
• Secondary locks on equipment/racks
• Conduit or tamper protections for wiring
• Protection from lightning and or surge
• Backup power and or uninterruptible power supply (UPS)
• Heating, cooling, air flow
• Appropriate fire detection/suppression
• Emergency shutoffs for high power connections

Improper management of a cabling plant can cascade into a variety of other problems, as shown in the photo. For example, many infrastructures develop organically, and, as result, lack comprehensive inventories or wiring diagrams of their cabling plant.

Coupled with substandard installation practices such as failing to mark cables or using the improper type of cable for a particular application, this presents a wide range of maintenance problems as new cable is installed in the cable trays, ceilings and under the floors.

Often reflecting the various generations of wiring in layers of cable, additions to the wiring plants of existing buildings significantly increases the fire load in the structure. In extreme cases, the physical weight of the cable in the overloaded trays can cause the tray to fail. In short, the maintenance failure in one part of the building system has ripple effects that could significantly affect the safe operation of the facility.

This problem has reached such proportions that many jurisdictions, including the U.S. National Electric Code, require the deinstallation of cable that has not been marked and reserved for future use. Deinstallation, however, comes with its own problems as the abandoned cable is usually at the bottom of the trays, and removing it stresses the remaining cables still in use.