Structuring Cabling

What is structured cabling?

Structured cabling is the highway that information travels on in a building. The building can be large or small, commercial or residential, or a combination of both as in the mixed-use retail, commercial, and residential buildings now found in most large cities. Structured cabling systems are designed around telecommunications code standards to ensure that computer equipment will operate as designed when connected to the structured cabling system. Some of these factors include distance limitations, cable types, flammability ratings, and bend radii.

Cat5/Cat6 what’s the difference?

The general difference between Cat5e cabling and Cat6 cabling is in the transmission performance and extension of the available bandwidth from 100 MHz for category 5e to 250 MHz for category 6. This includes better insertion loss, near-end crosstalk (NEXT), return loss, and equal level far-end crosstalk (ELFEXT). These improvements provide a higher signal to noise ratio, allowing higher reliability for current applications and higher data rates for future applications.

Do I need Plenum or PVC?

Plenum cable is designed to operate in a “return air” space in the building. Typically these spaces are above a suspended ceiling or beneath a raised floor. They are said to be a “return air” space because that is where the HVAC system gets the air to the heat or cool. If ever in question, the building inspector is typically the AHJ (authority having jurisdiction). Plenum cable is more expensive than PVC because of the less flammable compounds used in production. A plenum cable must pass a burn test that measures flame spread and smoke emissivity when exposed to the flame of a certain intensity and duration.

Do I need 1 or 2 cables per work area?

This decision is a commonly debated topic. The fact is that the cable is very inexpensive relative to the entire telecommunications system and the building that it serves. The increased functionality and bandwidth that one additional data cable can provide at each work area outlet can prove to be priceless, especially after the drywall is in place.

Do I need a cabinet, can’t I just plug straight into my equipment?

A cabinet is always recommended even for the smallest installs. Cabling plugged directly into equipment has a tendency to break away at the termination ends as the solid cable is not suitable for direct termination. Also, a cabinet provides protection for the equipment from theft, breakage, dust, and employees. Cabinets also allow all the equipment to be stored together and in a manageable way for moves and changes.

Why do I need such a big cabinet?

The cabinet should be large enough to house the current equipment with some space for possible future requirements. I.e. for a VOIP telephone system to be housed. The depth of the cabinet should keep in mind what is to be stored in the cabinet. Some ISP switches and blade servers are extra deep and required an 800/1000mm deep cabinet.

What do Data cable installation test results show?

Test Results show a range of tests depending on the grade of cabling used (Cat5e/Cat6 etc.). These tests for Cat6 include Wire Map, Length, Insertion Loss, NEXT Loss, PS NEXT Loss, ACRF Loss, PS ACRF Loss, Return Loss, Propagation Delay, and Delay Skew. These are tests to ensure installation standards have been met, the terminations have been done correctly and that the cable doesn’t have any unnecessary bends, kinks, and twists.

What should the end deliverable be for a structured cabling system?

When properly designed and installed, the end deliverable should be a structured cabling system that supports the customer’s needs now and well into the foreseeable future. The Main Distribution Frames and Intermediate Distribution Frames should be well thought out, and cables should be neatly dressed. It should have additional cable runs that support a wireless overlay and have sufficient bandwidth in the backbone to handle a step-change in bandwidth needs. For the last 20 years, clients have utilized more bandwidth in the current year than the year preceding it. Nobody ever says “we put in too much cable.”