With the growing adoption and use of modular furniture by the commercial building industry, any discussion concerning structured cabling without consideration of the TIA/EIA-568-B.1 recommendations concerning “Open Office Cabling” is insufficient. This very critical work area space must be planned for to ensure that the voice/data/video (VDV) cabling does not destroy the modularity of these furniture systems.
In 1996, The TIA recognized the need to address open offices and published TIA TSB-75 Additional Horizontal Cabling Practices for Open Offices. The basic recommendations found in this document have been incorporated into the release of TIA/EIA-568-B.1, giving this cabling methodology the full status of a recognized standard. The recommendations for open-office cabling are now found in clause 6, Work Area, of TIA/EIA-568-B.1.
Open-office cabling recommendations are intended for any open office space and can be employed for such areas as laboratories, training rooms, classrooms, as well as office areas using modular furniture. These recommendations and methodologies have also been employed with the new modular wall systems.
Open office cabling recommendations are intended to provide a cabling system that allows for easy and cost- effective reconfiguration of work areas (modular furniture) while providing a system that can be maintained and administrated without degrading the overall cabling system performance.
One can choose between two basic approaches when implementing an open office cabling solution—the multi-user telecommunications outlet assembly (MUTOA) or the consolidation point.
The simple distinction between the two approaches is that the consolidation point is an intermediate connection point between the telecommunications room and the work area outlet, so that the link has three connection points, whereas the MUTOA still has only two connection points in the link.
Another distinction factor with the consolidation point is each user has an outlet in his or her work area, whereas with the MUTOA, multiple users share an outlet, which is probably not actually located within their work area. It appears that the consolidation point approach has the greater market acceptance of the two approaches. Because often times either the MUTOAs or the consolidation points are placed in the open-office area in a structured pattern, with each one serving a specific area or “zone” of users, open-office cabling is also referred to as zone cabling by many.
The MUTOA is intended to address those areas where office reconfiguration occurs very frequently. Basically, the MUTOA allows a single-outlet assembly to be used for multiple users versus for a single user and allows for longer work area cords than the traditional 5 meters. A typical example of this would be when a number of users are clustered around a telecommunications pole in a circular fashion and a single-outlet assembly serves all the users.
Another example may be in a training room or laboratory environment where a single outlet serves multiple users sharing a large table. Some of the rules for a MUTOA implementation include:
• MUTOAs should be limited to serving a maximum of 12 work areas.
• MUTOAs should be located in fully accessible, permanent locations and shall not be located in ceiling spaces or obstructed areas.
• MUTOAs shall not be installed in furniture unless that unit is permanently secured to the building.
• MUTOAs are to be administered the same as outlets and additionally the connector types used in the MUTOA are to be the same as allowed in traditional outlets, i.e., eight-position modular jack for copper and either duplex SC or SFF connector for fiber.
• Because longer work area cords are allowed, copper systems must take into consideration the increased attenuation of stranded patch cords. The allowed 90-meter link distance is reduced when a total of more than 10 meters of patch cords is to be used in the telecommunications room and work area.
The consolidation point is intended for open-office areas that will not be reconfigured as frequently as those that may employ the MUTOA system. The consolidation point allows for an additional connection point in the horizontal cabling system and still provides an individual work outlet within the user work area. Listed below are some of the requirements for the consolidation point:
• The connector type is not specified; however, the connecting hardware shall meet the performance requirements of B.2 for copper and B.3 for fiber and be rated for at least 200 cycles of reconnection.
• Interconnections, not cross-connections, shall be used at the consolidation point.
• No more than one consolidation point (connection point) shall be allowed in the same horizontal cable run.
• For copper systems, the consolidation point should be located at least 15 meters (49 feet) from the telecommunications room to reduce the effect of multiple connections in close proximity.
• The consolidation point should be limited to serving 12 work areas.
• Consolidation points shall be located in fully accessible, permanent locations that are not obstructed. However, unlike MUTOAs, the consolidation point can be located in the ceiling and a number of consolidation point products have been released for use in the ceiling and also raised floor environments.
• Consolidation points shall not be installed in furniture unless that unit of furniture is secured to the building. Note the deletion of “permanent” stated with the MUTOA. A number of furniture manufacturers have released products that incorporate consolidation points into the furniture walls.
• Because the cable on both sides of the consolidation point is considered part of the horizontal cabling and, in the case where copper solid wire cable is to be used, the distance limitations do not change from 90 meters, the 90-meter distance applies to the total distance of the horizontal cabling from the telecommunications room to work area outlet, with the consolidation point being placed in the run based on office layout.
One implementation of the consolidation point that, while not specifically addressed in the standard, is allowed for and has a high degree of market acceptance, is the use of factory-made cable assemblies to go from the consolidation point to the outlet.
These assemblies are available in fiber and copper and use a pre-installed jack on one end to go into the outlet and a pre-installed plug/connector on the other end to mate to consolidation point. This approach allows for reduced labor requirements not only during the first-time installation, but also more importantly during office reconfiguration.
While performance requirements do not allow telecommunication (VDV) systems to have the multiple connections points allowed with modular furniture electrical systems, the use of the MUTOA and definitely the consolidation point allows modular furniture to be modular.
BEAM is director of systems marketing at AMP NETCONNECT Systems. He can be reached at (336) 727-5784 or firstname.lastname@example.org.