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Structured Cabling Installation Practices - Part Three Installing a Structured Cabling System

Cabling for small, medium or large enterprises can include wiring of hundreds of feet of cables throughout a building that pass other types of wires, powerlines, pipes and cords. The process can involve lots of drilling, cutting cables and attaching jacks, all of which require forward-planning and knowledge of the specific requirements for each step.

This article is the third in our series on Installation Practices and it provides installers and planners a guideline with best practices to deal with the complexities of installing a Structured Cabling System. The guidelines listed are an integral part of the DINTEK warranty program and can help make the installation process more straight-forward and may help save both time and money.


There are four main stages in cabling installation which include:

  • ​Pre-wire: The initial stage of the installation process.
  • Main Cabling Install: The installation of horizontal and backbone cables.
  • ​Fit Off: The terminating of cables on to their connection points.
  • Testing and Certification: The 4th and usually the final stage of the installation process.

As mentioned above, this is the initial stage of the installation process, where plans are read, cable routes are planned and catenaries are installed. It is at this stage where all the hardware and accessories that protect and support the cabling infrastructure needs to be put in place before the main cable install.


Cabling Support Systems - Catenaries

Catenary Grids are used in some countries only – usually not in Asia and the Middle East. All catenary wires used in a DINTEK structured solution are recommended to be of minimum 10-gauge soft drawn PVC coated well-tensioned steel galvanized wire. Where catenary wires are not of the PVC coated type then every un-coated catenary wire must be bonded to one common earth.

​The catenary wires shall be supported at each end provided with supports in between at maximum 3mtrs to prevent undue sag and should be installed to clear all other services and the ceiling by 300mm. Tensioning of catenary wires should be by galvanised steel turnbuckles and the cables should be secured to the catenary wires with cable ties at maximum intervals of 300mm and changes of direction. If more than 24 cables (either Cat5e or Cat6) are required on a catenary or the 300mm distance requirements cannot be met, then either a second catenary wire or a cable tray will need to be used to support the cabling.

Catenary wires should be installed in such a way so that for a cable leaving the wire it shall have an unsupported length no greater than 1mtr before its next fixing, access or dropping down a wall. Never use another services catenary (such as Electrical/Security or Fire) to attach your cabling to. All telecommunications cabling must be supported by dedicated catenaries. Catenary wires need to be run square and true with no deviations to avoid other services and should be run parallel to the major axes of the building. Catenary wires should be designed and installed to be a minimum of 75 mm above the ceiling grid which supports the ceiling.


Cabling Support Systems - Vertical Drop Preparation

When preparing your site for cabling, the partition wall may already be in place, or the walls may be existing. Where cables are to be dropped down a steel partitioned wall, all holes cut into the top plate through which the cables will be dropped need to have the sharp edges of the holes protected using an approved cable bush or similar product that will protect the cable from being damaged. All holes that are drilled through either steel partition or wooden nogged walls need to have a separation from electrical cabling of 300mm or more. This is to prevent EMF voltages being induced into the data cabling, which will degrade the system once in service.

Non-continuous cable support mechanisms such as hangers, rings, and hooks shall not be spaced farther than 1.5 m (5 ft) apart and telecommunications cables should be supported with devices designed for this purpose and installed independent of any other structural component. Backbone or horizontal cables routed vertically between floors should be supported with clamps, cable trays or other mechanisms. Non continuous supports occur at least 2 times between each floor. (Providing this support will limit the stress caused due to gravity on the cables.)


Cabling Support Systems - Cable Trays

By far the best way to reticulate large amounts of cables is to use a cable tray. The cable tray should preferably be of the rolled edge variety using correct joints, spacers, reducers, T's crosses and bends and needs to be of a sufficient size so as to allow for at least 30% of additional cables in the future. The cable tray also needs to maintain a minimum of 300mm access headroom above the cables. When a cable tray or catenary passes through a wall, it should be an unbroken length.


Cabling Support Systems - Trunking

The absolute maximum capacity in trunking should not exceed 60%, with 40% being preferable for the accommodation of unplanned additions at a later date. Steel trunking, particularly carrying electrical, needs to be earthed. Corners should not exceed the minimum bend radius – particularly smaller capping.


Cabling Support Systems - Equipment Room & Telecommunications Room Set-ups

Although the designer should have determined the exact placement and spacing of racks in the Comms closet or Comms room, the standards provide spacing and clearance guidelines that the installer should be aware of.

Freestanding Cabinets: Once the rack/s are spaced and placed they need to be securely fastened to the floor. In seismic areas, the rack should have additional bracing required by building code or a specified by structural engineer. It's good practice to install a ladder rack with lots of cables inside the cabinet. There should be an aisle of at least 800mm in both the front and rear of the racks.

Wall Mount Racks/Cabinets: Wall mounted cabinets are used where the space needed for patch panels and associated equipment does not require a full size free standing cabinet or rack or where space is limited. These cabinets can become very heavy when fully loaded with cabling, patch panels, switches etc etc, so the fixing method should go into the studs or anchor into the concrete, and not just into the gib wall using some kind of hollow wall anchors. Where this is not possible then a backing board, typically made of MDF or particle board, should be attached to the wall first and then the cabinet attached to the backing board. 

The cables should be supported where they enter and leave the box to avoid any extra weight strain being placed on the box. Remember to leave plenty of space around the front of the box to allow for termination and maintenance, as most wall mounted cabinets used swing off the wall from the back, not only from the front. Also, use common sense and leave some room for anything that may come along (i.e. cable routing, etc.). If the height is not specified, mount the box a minimum of 500mm off of the floor - the higher the better - and in a logical position for ease of terminating/splicing. Also, be mindful of when the cabinet will be in a high traffic area. The cabinet should either clearly visible to any traffic, or be mounted high enough, that users will not end up walking into the cabinet. 

Allowing adequate cable management/support hardware and management accessories in the Equipment Room is vital for the management and looming of the cables. Management for both the back and the front of the cabinet, and for both the vertical and horizontal cabling should be included. By not allowing adequate space for cable management, termination and connection problems can occur, thus creating the possibility of permanent or intermittent faults. Cables looms should be attached to the cabinet management system (typically cable tray) by either Velcro or cable ties, depending upon either Cat5e or Cat6 being used. At the wall outlet it is important that the bend radius limitations, amount of untwist (for twisted pair/balanced cable), and stripping procedures be adhered to and that the proper termination procedures are followed.


All of the cabling hardware and accessories are now in place, so the installation of horizontal and backbone cables can now get underway. Some of the primary installation concerns that should be addressed during the installation of a twisted pair cabling system are listed below. ​All of these issues need to be considered individually during a UTP or STP installation project, because they all have an impact on the performance of the cable. 

Installation Pull or Tensile Load 

Bend Radius 

 Compression

 EMI

​When installing Cat5e or Cat6 cabling, strict adherence to the applicable installation guidelines and specifications of that type of cabling are required, as Cat5e & Cat6 are far more susceptible to performance problems than telephone wire, and even optical fiber. Although it may say Cat5e or Cat6 on the jacket of the cable, if the installing technician doesn't follow the proper installation practices, the performance will be unacceptable, the test results will prove it and therefore the site will not be able to be certified.

UTP Cable Installation 

DINTEK cable comes in 2 styles of boxes both designed to allow easy pulling directly from the box. The boxes contain 305 meters of cable (100 meter options are available) and the cable jacket is marked periodically with a length number. Note on the box you are using the proper placement for pulling to ensure the cable is not twisted or kinked when pulled. The most efficient way to pull horizontal cables is to pull out in bundles - do not pull it all out of the box before installing as it may tangle! Using drawings of the area, determine where all work areas are located and establish several consolidation points or clusters to pull from. Place all the cable boxes in the drop area and mark each as to the final location.

Cable Protection When Pulling

A conduit is used when cable damage is possible, for example in factories where chemicals are present; where electromagnetic interference is likely; or if fire-stopping requires it. When pulling cable into the conduit, the cable can be damaged by the roughhack sawed end of a conduit, so special nylon bushings are used to prevent abrasion. If it's a long pull with high friction, use a lubricant; and with intermediate boxes it is recommended to make short pulls. 

Cables should not be pulled over or around sharp objects, and when pulling around tight corners, a cable elbow (pictured) should be used.

Hanging Cable 

​You cannot lay cable on ceiling tiles or grids as it violates codes. Cables need to be laid a minimum of 100mm above the ceiling. To prevent kinks, do not lay cable bundles in wire hooks that are used for electrical cables, and it is recommended to use wide j-hooks that spread out the load on the cables (spaced at 1.5 meters max). Do not overload the j-hooks as it can damage the cables on the bottom.

Bundling Cable 

When any number of cables are bundled together in long parallel lengths, the capacitive coupling of pairs in different cables in the bundle with the same twist rates (eg. blue pair to blue pair) causes cross alk interference to increase sharply. This is known as "alien crosstalk". The best way to minimise the adverse effects of alien crosstalk is to minimise the length of long parallel runs and install bundles of cable in a pseudo-random fashion (ie do not go for the aesthetically pleasing uniformed looms). Forming the cables into bundles as they lie is the best way to avoid the chance of any two pairs from different cables lying parallel with each other for any significant length. 

Be careful with cable ties - too tight and it will crush the cables and potentially cause crosstalk failure. If you do use cable ties, do not use cable tie 'guns' to set them, instead hand tighten them and cut off the ends to prevent future tightening. It is preferable to use 'hook and loop' fasteners which are now widely available and also give the option of being re-opened for adding or removing cables at a later date. 

Installation Pull or Tensile Load 

Tensile Load is the amount of 'stress' that can be placed on a cable before a cables performance begins to breakdown. This stress can be placed upon the cable during the installation pull. The maximum installation pull of Cat5e & Cat6 UTP (as stated in the ANSI/TIA standards) should not exceed 8-10Kg per meter or 25 lbs./ft.

But, when you're out on site, just how do you measure this tension? Well, obviously you don't carry a tension meter around with you on the job, and although you could use something like fishing weight scales to measure pull force, common sense and avoiding carelessness will ensure that the pull tension maximum will not be exceeded. One thing to remember is that when pulling multiple cables, the stress load limitation does not increase (i.e. 2 cables does not equal 50 lbs.) and the installer needs to be a little more aware not to exceed the maximum limits. The installer should keep the pull tension as low as possible, because the higher the tension - the higher the probability of damage to the cable.

Following are some tips and guidelines to help ensure that the maximum tensile load is not exceeded:

  • Limit the 90° bends in a single cable run in conduit, to two.
  • Cable should not be pulled through a length of conduit exceeding 30 meters.
  • Support the cables every 1.2 meters - 1.5 meters to prevent excessive weight strain and hanging load.
  • Avoid sharp objects, turns and corners.
  • Use a third man at turns and corners.
  • If cable becomes 'tight' or 'stuck' do NOT jerk cable - go back and free the cable.
  • Pull around obstructions such as air conditioning ductwork as required.
Bend Radius 

The Bend Radius is how far the cable can be bent around a corner or angle towards itself before significant damage occurs. When installing cabling, you will need to keep the cable bend radius to no less than 4 times the cable diameter for four-pair UTP cable, and where multi pair UTP cabling (for example 25pair Cat5e) then you will need to keep the cable bend radius to no less than 10 times the cable diameter. 

The standards do not differentiate between the bend radius when the cable is being pulled and when the cable is static. Also, bending twisted pair (balanced) cables into service loops is not recommended.

Compression 

Excessive compression of the cable adversely affects the cable's characteristics both physically and electrically. The following guidelines will help prevent unwanted compression of the cable:

  • Avoid stepping on the cable. It will crush and displace pairs. It may not show, but small damage is highly likely to have occurred.
  • Avoid the over-tightening of cable ties. This will also crush and displace pairs. Damage will be cumulative for every crush! The cable should be able to move under the cable tie.
  • Avoid stapling. If you need to use staples, do not use an automatic stapler as it puts stress on the jacket. Instead, use a UTP insulated staple or nailed clip.
  • Do not overload cable pathways. The weight of the cable bundle may crush the cables underneath and possibly pull the pathway away from its attachment.

When it comes to compression, there is a considerable difference between Cat5e and Cat6 cable. Compression of Cat5e cable is critical due to the geometry of the cables. This is due to the way that pairs are balanced between each other. Compression moved cable pairs away or together but always within the confines of a relatively small sheath i.e. a limited distance.

DINTEK Category 6 cables have a central spacing member designed to reduce NEXT and ELFEXT. This makes the cable diameter larger and hence the room available for cable pairs to move is also increased. Compression has an even greater effect on Cat6 cable performance - which means that even greater care must be taken when pulling the cables and also dressing the cables in compared to Cat 5e.

Using velcro ties limits compression, however it is important that you do not over tighten. The effect of losses are cumulative, so every over-tight cable tie will add to the total loss. For example, consider a 40 meter run, over tied every 300mm, means 120 instances of performance degradation. It is for this reason that only Velcro ties or approved extra wide standard cable ties, should be used when tying DINTEK Category 6 cabling to trays, catenaries, or cable management. Velcro ties will make it virtually impossible to damage the cable by compression. They are also easily removed, which makes the addition of more cables to the bundle an easier process.

Cable Kinking 

As DINTEK Category 6A cables contain a central spacing member it is also of vital importance to ensure that cables are not kinked or that bends are below the minimum. Again this spacing member is critical to the performance and once a cable is kinked there is a very marked difference in its electrical performance and it should be regarded as damaged and to be replaced. While installation pressures will tempt the installer to straighten the kink, the damage however, has already been done as will be seen when the cable is tested. This will result in much more time wasted at the other end of the project. Remember that all these effects are cumulative so whilst one kinked cable is unlikely to produce a fail, when added to the deterioration factors and the reduced headroom of say, Cat 6A, it may do.

Electromagnetic Interference (EMI) and Other Interferences 

Avoid areas where the cables will be exposed to high temp-eratures, such as lighting, heat, open flame, etc as high temperatures affect attenuation.

Avoid laying cable in areas with excessive moisture such as damp basements and areas where steam will form condensation on the cable.

When installing UTP cabling, avoiding the laying of cables near noise sources, electrical wiring, electric motors, fluorescent lighting and other Electromagnetic Interference (EMI)/Radio Frequency Interference (RFI) devices is imperative. These environmental parameters can have a severe effect on cabling performance. Installing the cable in a closed metallic pathway such as a conduit will help reduce the effects of EMI. 

If the cables are not installed in a non earthed sheathing situation, such as within metallic earthed conduit, a common minimum distance of 300mm away from electrical cabling, and electrical fittings, particularly fluorescent fixtures should be observed. 


Minimum separation requirements may be found in the ANSI/TIA-569 standard (Industry recommendations for performance) and AS NZS 3080 - 2003. Also, be sure to follow any and all local codes, standards and regulations. 

Following these guidelines will help ensure that the mechanical and electrical characteristics of twisted pair (balanced) cable will remain intact for ultimate cable performance. Some of these guidelines are relevant for optical fiber also, but optical fiber does have its own share of installation guidelines that should be followed. 

Does Cat6 and Cat6A cable differ much from Cat5e when it comes to installation? 

The emergence of 10 gigabit is the latest challenge facing cabling and networking developers when it comes to installation and testing procedures. It only stands to reason that these higher speeds come with additional specification requirements. As a totally new cabling, Category 6A comes with specific design and performance criteria, and does have significant differences from Category 6 cabling in certain areas. Most notably is the greatly increased effect of alien crosstalk on Cat 6A cabling.

As noted earlier, alien crosstalk is electromagnetic noise that can occur in a cable that runs alongside one or more other signal-carrying cables. The term "alien", arises from the fact that this form of crosstalk occurs between different cables in a group or bundle, rather than between individual wires or circuits within a single cable. Alien crosstalk can be particularly troublesome because, unlike the simple crosstalk caused by a single interfering signal, it cannot be eliminated by phase cancellation. Alien crosstalk arises from multiple signals, and includes mixing products in which phantom signals at innumerable sum and difference frequencies blend with the originating signals.

DINTEK's PowerMAX Cat6A twisted pair cable minimizes alien crosstalk, provides excellent signal isolation and superior electromagnetic interference protection.

Does this Cat6 installation look good? Nice and neat for Cat5e, but not a good idea for Cat6A
Install cabling in randomly laid fashion
Other considerations 

Cable Pulling Tension: Do not exceed the cable pulling tension of 25lb / ft as specified in TIA/EIA standards. Excessive tension will deform the lay of the pairs in the cable and severely affect the cable's ability to reject unwanted noise (NEXT, FEXT and their derivatives. This can result in pair untwist and potential conductor damage.

Cable Bend Radius: Avoid sharp bends in the cable, as it will alter the lay of the pairs in the cable. In excessive bending, pairs may untwist, causing an impedance mis-match and an unacceptable return loss performance. Alternatively, the relationship between the lay of the 4 pairs within the cable may be altered. That, in turn will cause problems with noise rejection. We recommend that cable bend radius should be no less that 4 times the diameter of the cable post installation. 

For a typical Cat6 cable, that means a bend radius of greater than 25 mm. One of the most crucial areas where this is a problem is wiring cabinet, as large numbers of cables are brought into the patch panels and the tendency to make the cable looms neat causes some cables to be compressed and bent too tightly. Often this is unseen, and even the most diligent of installers may inadvertently be deteriorating the performance of the cabling system.

For example, when replacing Cat5 cabling for Cat6, it may be that the Cat5 cabling was run in 16mm capping with corners. Not only will there be less room in that capping now, but the bend radii created in order to use the same 16mm capping would be unacceptable, therefore other means of reticulating the Cat6 would need to be employed.

​DINTEK's ezi-TOOL180 for use in Cat6A, Cat6 or Cat5e installations

This may also be a problem when running Cat6 and fitting off keystones into wall mounted anodised trunking and or mounting blocks. 

Using traditional 90degree jacks in this instance is not advisable, as it does not allow enough room behind the keystone for adequate bend radius.

In this situation, it would be best to use DINTEK's 180degree rear punch-down tool, meaning that the cable can lay straight onto the keystone without the need to bend around and into trunking etc.


The fit-off process involves the terminating of cables on to their connection points. To do this, we will go through the individual steps for a Cat6 termination using three DINTEK products - the PowerMAX Cat6 ezi-JACK; a Keystone Jack Working Base and the DINTEK ezi-TOOL180.

Step One 
Using a pair of strippers, strip approx-imately 40mm (1.5 inches) of jacket from the cable. One turn only.
 Step Two
Separate the wire pairs away from the central spacing member. DO NOT UNTWIST.
 Step Three
Use cutters to remove central spacer, as far down without damaging the wire insulation.
Step Four
Using a Keystone Jack Working Base, insert the Cat6 ezi-JACK onto it, as pictured.
 Step Five
Lay wires onto Keystone as per 568B color spec, push wires down ready for punchdown with the ezi-TOOL.
 Step Six
When wires are ready for punchdown termination, check color coding, untwist amounts & insulation.
Step Seven
Using the ezi-TOOL, insert the ezi-JACK Keystone into the ezi-TOOL as pictured.
 Step Eight
In one movement, close crimp tool & release when excess wire pieces have been cut away by ezi-TOOL.
 Step Nine
Remove the ezi-JACK from the ezi-TOOL. Take the Keystone cover cap, and clip into place securing wires.
Step Ten
The finished ezi-JACK should look like this with the cable jacket right up to the end of the jack.
 Correct ezi-JACK Termination
Why is this correct? Jacket reaches to end of jack and twists are intact right to the terminals.
 Incorrect ezi-JACK Termination
Why is this incorrect? The untwist in the pairs causes near end crosstalk as described earlier in the article.

This will be covered in our final article of the series. Watch this space!

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