Taming office dynamics with cable management

The office is a fluid environment - nothing stays the same for long. Staff relocations, departmental restructuring, workgroup reorganising and network upgrading seem to be the day-to-day norm. But if it's so normal, how come businesses still struggle to cater for it in the cabling infrastructure?

The very name that defines our business - 'structured cabling'- implies orderliness and manageability. But that's not usually the case after the dynamics of an office take effect. Even after just a year of use, most wiring closets look anything but structured after being subjected to constant adds, moves and changes.

But good administration is achievable in all cabling installations if some basic design and operational rules are adhered to. "How would you know?" I hear you ask. Well, considering I designed and project managed Australia's first major structured cabling system with 5000 outlets and 36 wiring closets in 1986, years before there was a cabling standard, then promoted structured cabling for many years with Mod-Tap/Molex and Belden and was recently the cabling administrator at ColesMyer (see story in Jan/Feb 2006 Electrical Solutions), I do have an informed opinion on the subject.

I've been a strong advocate of cable management over these years, because I've seen and experienced the consequences of good and bad cable management. It amazes me that it's still an issue, despite the maturity of structured cabling and its ubiquitousness (big word that just means that everybody uses it nowadays).

Sixteen years ago, while at Mod-Tap, I influenced the Telecom Australia (for you Gen-Y readers, that's Telstra's previous name and for you old blokes, that's what PMG became) standard operating environment (SOE) specification to include cable management in their wiring closets. During the pre-tender inspection of several Telecom sites, I found no cable management in any of the wiring closets. Just 42 RUs of patch panels and hundreds of black patch leads. The Telecom engineers running the tender took my advice and amended the specification to include cable management. Since then, Telecom/Telstra has been fastidious about proper cable management. And for good reason - its offices are constantly changing. A Telstra technician once told me their Melbourne head office had an annual churn factor of 300%! To their credit, good cable management meant they could handle this high office movement with ease and minimal disruption to business as people changed locations and functions.

Few companies are that proactive in administering their office dynamics. That's because it's unimportant to them - until something tragic happens.

To save them grief, cabling designers and installers can provide a structured cabling system that's truly manageable, along with some education on using it to their advantage for years to come. A little forethought and good design principles go a long way to avert later problems.

Years ago, I coined the phrase "cabling systems don't break down; they just go out of control" and I believe that's still true today. Cabling is mostly static. The only things that move are patch leads and that's where problems often occur - when connections aren't documented or connected to wrong services, because of poor cable management by the end user.

Office dynamics

Churn factor describes the dynamics of an office. It's defined as the number of changes made to the cabling infrastructure each year, divided by number of staff in an office. Using Telstra as an example with say, 4000 staff in its head office, a 300% churn factor would mean they would make 12,000 changes every year. That's 120,000 changes over the past 10 years! Imagine the mess if they weren't proactive in good cable management.

From past research, I found the average office churn was 40-60%. So half the staff would typically require a change to their cabling of some sort each year. Generally, the larger the company, the higher the churn factor.

Office churn impacts cabling in three main areas: wiring closet, work station and route to the work station. There are numerous design considerations, products and administrative tasks that can be applied to facilitate good cable management.

Cable management in wiring closets

It's normal practice to include a one- or two-RU cable management panel between every two rows of patch panels to direct patch cords away from the patch fields and then vertical channels to route the patch cords elsewhere. Some end users and surprisingly some installers still insist on minimising this just to fit more patch panels into a cabinet. But imagine a 42 RU cabinet filled with fully interconnected 24 port patch panels - 1008 patch cords. Now imagine what that would look like after a year with 100% churn. A thousand re-connections carried out by the end user who has no idea about uniformity in the patching field.

Do your client a favour and install horizontal and vertical cable management panels in the patching field. All cabling manufacturers offer these panels, so talk to them to find the most suitable for each of your projects.

Here are some tips in choosing and using them:

• Horizontal and vertical channels should be large enough to comfortably accommodate all patch cords likely to be patched. I say 'comfortably' because when end users start changing connections, they'll inevitably have to fish out patch cords from the back of the channels so they'll be grateful if you make it easy for them to find the right cords and pull them out without too much hassle.

• Ensure panels don't have sharp edges that can catch or cut the patch cords.

• Use panels with 'fingers' that have a little 'give' in them, so if patch cords bend around them and inadvertently get pulled on, the finger will bend a little so cords aren't deformed and transmission performance degraded.

• Make sure vertical panels have good lead-in from the horizontal panels to prevent patch cords deforming over sharp edges, which will adversely affect cable transmission performance.

• When sizing vertical panels, remember that patch cords are often looped in the channel (ie, down from one panel and up to another, with the slack taken up in the vertical cable manager), so twice the number of cords will need to be accommodated.

• Keep patch panel labeling as unobstructed as possible so end users can find the outlets they need to change as easily and accurately as possible.

• Allow patch cords to be a little 'messy' in the channels to minimise the possibility of alien crosstalk, especially in high data speed applications. In other words, make sure patch cords aren't perfectly aligned in parallel with each other in the vertical or horizontal cable managers.

If there isn't space for horizontal cable managers - often a problem in high-density applications like call centres and dealing rooms - don't just neglect it and hope for the best. Have a look at ADC Krone's Glide, a system that routes cords from patch panels directly to vertical channels on the rack's sides, without using horizontal cable management panels. It frees up a lot of rack space, but because of the increased density of patch cords and connections, it can get untidy if end users don't utilise it properly. Some education goes a long way to ensure they understand how to use it properly. If you're thinking of using it in a project, get ADC Krone in to step you and/or your client through the process of using it properly.

The Glide panels manage excess lengths of cable through a series of vertical spools called 'slack managers' located within the panels. Each panel also has a rib cage, which is its own set of outer cable managers, designed to accommodate patch cords at the front of the rack and terminated solid cables at the rear.

Conclusion

Even though your responsibility as a cabling contractor or designer finishes when the structured cabling system is completed, commissioned and perhaps certified, your client is just beginning theirs. Thinking longer term, considering various alternatives and taking some simple initiatives can make it so much easier for end users to live with their cabling system and view it as an asset rather than a liability to their business. Remember, "cabling systems don't break down; they just go out of control".