A Room by Any Other Name: The Telecomm or Distributor Room

The distributor room is what veteran IT professionals call the telecommunications room, telecommunications closet, wiring closet, and/or equipment room.

Although the name is newer,  the functionality basically remains the same.

Defined in ANSI/TIA-568-D Telecommunications Pathways and Spaces (2015), the distributor room is the common access point for a building's pathways and cabling horizontal and backbone subsystems. The standard focuses on the telecommunications aspect of building design and significantly influences the design of other building services, such as electrical power and HVAC. It standardizes specific pathway and space design and construction practices in support of telecommunications media and equipment within buildings.

The distributor room houses telecommunications equipment, cable terminations, and cross-connects that serve a specific office area or a specific floor. It may also house related networking and building automation systems and equipment. The standard specifies that equipment not related to telecommunications shall not be installed, pass through, or enter the distributor room. This includes electrical equipment (other than that to power the telecom equipment), piping, ductwork, tubing, etc.

Depending on size, a building may have more than one distributor room connecting to the equipment room. One per floor is specified in multistory buildings and they are typically located above one another. The distance between end devices at the work area and the telecommunications room is 90 meters.

In a similar name change, the telecommunications enclosure is now the distributor enclosure. It's an enclosure that houses the telecom and networking equipment in small offices or in remote areas. Also, the telecommunication outlet space is now called an equipment outlet space. Most of us know it by the term work area outlet.

Distributor rooms have been called IDFs (intermediate distribution frames or intermediate cross-connects) or MDFs (main distribution frames or main cross-connects). This is a bit of a misnomer as the IDF or MDF is the physical racking system which holds the cross-connects between the cabling horizontal and vertical cabling systems.

Updated in 2015, the ANSI/TIA-569-D standard specifies smaller, minimum recommended distributor rooms sizes: 9 m2/100 ft.2 for the intermediate backbone and 11 m2/120 ft2 for horizontal cabling.

The update reduced the clearance requirement above cable trays from 12" minimum to 8" minimum; 12" is recommended. It also recommends but does not require that the maximum cabinet and rack height be 7 feet.

This revision in 2015 also includes the addition of bonding requirements for metallic pathways, as well as the multi-user telecommunications outlet assembly space and consolidation point space.

Updates in 2013 and 2014 revised distributor room temperature and humidity specifications. The standard adopted the revised 2012 ASHRAE thermal guidelines for data processing environments to provide more energy savings.

Temperature: 5 – 35°C (41 – 95°F) dry bulb

Relative humidity (RH): 8 – 80%

Maximum dew point: 15° C

In addition, the maximum twisted-pair cabling distances were reduced when the temperature is above 20°C. For example, at 60° C, the maximum permanent link would be 75 meters for UTP cable.


Lighting shall be a minimum of 500 lux in the horizontal plane and 200 lux in the vertical plane, measured 1 m (3 ft) above the finished floor in the middle of all aisles between cabinets and racks.

Lighting fixtures should not be powered from the same electrical distribution panel as the telecommunications equipment in the space.

Dimmer switches should not be used.

Clearance from equipment

Front clearance of 1 m (3 ft.) shall be provided for installation of equipment. Front clearance of 1.2 m (4 ft.) is preferable to accommodate deeper equipment. Rear clearance of 0.6 m (2 ft.) of shall be provided for service access at the rear of racks and cabinets. Rear clearance of 1 m (3 ft.) is preferable.

More Details

The standard can be purchased from IHS.com.

network infrastructure Structured Cabling Telecom Room
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