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Infrastructure Design: What You Need to Consider When Accommodating Copper & Fiber Cabling

Fiber Optic Infrastructure
Posted by James Donovan on 20 September 2017 Connect with James on LinkedIn Estimated reading time: 5 minutes

How often do you think about the practical accommodation of network infrastructure?

While network infrastructure may not be known for it’s aesthetic value – rarely does it go on display in museums or in the pages of art books or magazines – it is still important to consider network design, as this impacts on performance, quality and functionality.

As these factors are the priority for infrastructure success, it’s unsurprising that how network infrastructure actually looks has not been a major consideration until recently. But, both practicality and visual clarity should play a part in successful network design. This is because aesthetics aren’t just a matter of products looking nice and neat, but rather, the infrastructure being designed and installed in such a fashion that it is out of the way, easy to use and able to accommodate change, both in the immediate future and over the long haul.

Aesthetic and practical infrastructure considerations

cables

Copper & fiber cabling winds its way from the individual rooms and workspaces of the user to telecommunications closets or rooms positioned around the building or campus.

In the case of power and telecommunications, this will generally be from the users’ desks. Lighting and environmental control systems are also accessed from areas or zones within the ceiling or other voids in the building.

Building developers and others need to appreciate the increasing quantity of ‘category’ type cables resulting from structured wiring, and many buildings provide inadequate space. This is most often the case in the area where the cables from the horizontal distribution enter the telecommunications closet.

Therefore, one of the most important design considerations is how to design the communications room or closet, a room in which the communications backbone is connected to the horizontal distribution.

Historically, riser cupboards were used to accommodate the patch frames for telephone wiring schemes. Small riser cupboards have gradually increased in size to accommodate communication cables, patching frames and electronics.

This increased pressure on space in riser cupboards requires them to be substantially increased in size or supplemented by separate cable patching rooms. The term “telecommunications closet” is used to describe these larger spaces.

Telecommunications Closet Form, Fit and Function

The most basic limitation on the positioning of telecommunication closets is the need to keep the lengths of fiber & copper cabling within the limits set by the structured cabling standards and the associated network applications that ultimately will be used.

Since these are often not known when the building is designed, a maximum cable length of 90m, as specified in the cabling standards, should be used between the closet and the work area outlet. Four factors combine to reduce the office area that can be served from a single closet below that of a 90m radius.

Those factors are as follows:

  • The use of “street and avenue” horizontal cable routes.
  • The need to route cables around obstacles such as service cores and atria.
  • The need to avoid congestion in the areas where the cables approach and enter the closets. These areas also often are densely packed with other services.
  • The need to allow some spare cable length at the patch panel, and sometimes, from the closet to the outlet, to allow for change and movement in the future.

The area that can be served is further reduced when the shape of the building is considered. Riser positions often lead to the location of a telecom closet near a corner of the space to be used. The use of asymmetric risers, where the space served is divided between a number of closets, thus allowing flexibility and redundancy, also must be considered.

A wiring closet or cable patching room for a communication network that includes voice, data and building management systems needs to be large enough to contain cross-connect frames and racks for patching and some electronics for the LAN. It should be large enough for an engineer to work within, allow front access and back access to the cabinets and have space for additional wall mounted frames.

Closet Requirements:

Wiring closet designs should be flexible enough to allow expansion during fit-out, or subsequently, to form satellite equipment rooms or departmental computer rooms. It is desirable to provide a clear demarcation between passive structural space, such as a cable riser, and serviced space intended for active electronics, in order to accomplish the following:

  • Reduce the risk of fires spreading between floors through the risers. (Where space is shared with different services, the appropriate choice of cable should be made to meet the required level of fire performance to reduce the risk to the occupants, building and IT services.)
  • Keep HVAC ducting and pipework out of the communications risers.
  • Encourage clear demarcation of management responsibilities.

In a telecommunications closet, a raised floor or ceiling void is desirable to allow for cables to enter from the riser, connect to the frames and access the other equipment in the room. Sufficient space should be provided to connect cableways within the closet to those provided in the riser.

In order to make it convenient and efficient for technicians to work in the closet, it should be properly lit and provided with necessary services. The provision of suitable power supplies and earths should be provided from a relatively clean desk supply, and also sufficient cooling should be provided for the electronics.

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