Connect Communications | Cabling Help

Network Cabling Basics

This document has been assembled to assist the novice cable installer and make sure that minimum standards and requirements are met, and to provide a basic understanding of differences between Category 5e cable and Category 6 cable.

Category 5e or Category 6 Cable?

It is important to understand which cable is best suited to fit the needs of a given cable job. As of the date of this document, Category 5e cable is most commonly used, but companies who wish to "future proof" their voice and data networks are planning ahead and installing Category 6 cable.

How are they different?

Cat 6 cable has been designed to allow for less crosstalk and higher bandwidth and overhead. These factors provide a more robust solution for gigabit Ethernet than Cat 5e cable is able to accomplish. This does not mean that Cat 5e is unable to support gigabit Ethernet, it only means that it has a higher chance of near end crosstalk and other factors that will negatively impact your data network. Knowing this, you may wonder why any company would wish to install Cat 5e instead of Cat 6 cable. The number one reason to use Cat 5e cable is cost, which is approximately 35% less than Cat 6, assuming you are using standard riser-rated cable for your installation. What is not often considered is the long term costs involved in replacing your Cat 5e cable when it becomes an obsolete technology.

Which to choose

So which cable is best for your particular job? If you need a short term, inexpensive solution, Cat 5e is the way to go. If you are looking for a longer term, future-proof solution and will be staying in the office space you are cabling for a long period of time, then Cat 6 is the best choice for your company. It can sometimes be very difficult to justify the additional expense involved with installing Cat 6 cable, but if you consider the long term impact it could have on your business, you may gladly make the choice to spend the extra money. Data transfer speeds are currently doubling every 18 to 24 months, which means that cable with lower bandwidth capabilities will soon be unable to keep up with technology, and let’s face it, technology does not wait for you.

Pre-Assessment

Before you begin installing your cable, it is important to determine where the data closet will be located. The more centrally located this closet is the easier it will be for you to pull cables and the less likely you will be to exceed maximum cable lengths.

Cable length specifications

Maximum cable length should not be more than approximately 328 feet (100 meters), including the length of any attached patch cables. A good rule of thumb is to keep your cable runs around 280 feet (85 meters) to accommodate for patch cables that will run from the patch panel to switches and from the jack to the computer. If you are unable to keep all of your cable runs under 328 feet total, it will be necessary to establish another closet for data terminations, and at this point you may want some expert assistance in determining the best way to run a backbone between these two locations. These considerations will be largely dependent on your budget and bandwidth requirements.

Cable ratings

The second most important thing to determine is if your ceiling is riser rated or plenum rated. Plenum rated cable (also known as fire rated cable) is needed when the return air is being pulled directly from the space above the ceiling grid, or when specified by the architect or building owner. Some building owners and certain states require that all cable be plenum rated. It is best to consult with the architect and/or building owner prior to pulling your cable. A third source for this information is the HVAC contractor. Ask if the return air is ducted all the way to the ceiling tile or if it is drawing air from above the ceiling grid. Those who are familiar with heating and air conditioning ducts will be able to tell which is the main trunk line and which is the return air and should be able to see if the return air has been ducted all the way to the ceiling.

Installation

Once you have determined where your termination closet will be and what cable you will be using, you will need to determine the best path for getting your cables from the closet to the jack.

Things to consider

Will you be running your cables parallel with any electrical wires?
Will you be hanging cables over fluorescent lights?
Can you pull multiple cables to one location and then spread them out from there?
Is there a clear path for hanging your cables or installing some sort of wire management device to keep cables off of the ceiling?

Things to avoid

Never run your cables parallel with power for long distances or directly over the top of any fluorescent lighting. When possible, do not use electrical conduits to support your cables. (Understand, however, that not every cabling environment has the most ideal conditions, so in considering these things, use your best judgment and understand that sometimes you will need to bend the rules just a little.) If you find it necessary to run cable parallel with electrical wiring, try to maintain a minimum distance of 24 inches from the electrical wiring. It is acceptable to cross electrical wiring at a 90 degree angle, but where possible, try to support your cable in a way that prevents the two from coming in direct contact with each other. Many electrical supply companies can provide cable trays or J hooks for supporting your cable. If you are really lucky, you will pull through a ceiling that has girder type trusses that you can run your cable through to support it. This allows you to keep your cable off of the ceiling tiles without having to purchase any additional components. Do not lay cables on the ceiling tile or tie them to guide wires for the ceiling grid. In most areas this is against building code and will require your work to be done over again. It is much easier to do it right the first time.

Mapping a path

When considering the path your cables will follow, determine where conduits will be located for dropping cable into the walls. This will help discover points in the ceiling where you can pull multiple locations and then distribute them to their individual conduits. Depending on the situation, you may find it easier to pull from the termination closet out to the jacks, or you may want to pull from some other location near the jacks back to the termination closet. It is completely up to you to determine which method may be easiest.

Labeling

Before actually pulling the cables, mark the cable with a fine tip marker. We usually use numbers to mark locations, but you can use whatever suits you best. After marking the cable with a number, be sure to write that same number on the cable box so that when you cut the cable you can remember what number needs to be written on the other end. Doing this will give you a number on both ends, which will make it easier to label both ends of the cable so that you can terminate them in your patch panels in numerical order, and will make locating both ends for testing and connecting equipment much easier. An example of how to number cables can be shown in a job where cables are being pulled from the first and second floors of a building into one centrally located phone closet. If there are 40 locations per floor and each location has one voice and one data cable, we would label our cables on the first floor as 100-V through 139-V for the voice and 100-D through 139-D for the data cables, and on the second floor as 200-V through 239-V and 200-D through 239-D. Another thing we do to separate voice from data cables and make terminating them a bit easier is to use one color of cable for voice and another color for data.

Maintaining cable integrity

As you begin to pull your cables to individual locations, refrain from putting too much pressure on the cable or pulling the cable in a manner that causes it to bend sharply or kink at any location. A good rule of thumb on the bends in cable is to make sure that your bend on any one cable is never greater than the size of a silver dollar. You should also pull with no more than 25 pounds of pressure. If you find yourself pulling cable from the floor into a false ceiling you will quickly discover that it is easy to snag the cable in the corners of the grid, especially if the distance you're pulling is long. It may be easier to have one person on a ladder pulling the cable out of the boxes and keeping it from rubbing on the tile grid and a second person pulling the cables through the ceiling to the individual locations.

Another thing to consider is leaving a service loop at both ends of the cable. A service loop should be left directly above the jack at one end of the cable and somewhere above the ceiling at the termination closet. We recommend leaving from 2-5 feet above the jack, and approximately 10 feet of additional cable above the termination closet.

When securing your cables together or to something else for support, there are a couple of popular options. Cable manufacturers recommend Velcro straps, but plastic wire ties are easy to find and easy to use. Either way, make sure to not over tighten them, as this will smash the cable and can change the electrical properties of the cables.

Maintaining the integrity of the cable is a priority, which is why we warn about overtightening tie wraps, pulling too hard on the cable, kinking the cable, or bending the cable too sharply.

Termination

Once you have pulled all cables to their locations and have labeled both ends, you will need to separate and terminate them.

Tools

Assuming you will be terminating both voice and data cables to a patch panel, you will need a 110 punch down tool, also available from a local electrical supply. If you're unfamiliar with how a punch down tool is used, they should be able to show you. If you choose to terminate your voice cables to 66 blocks, you will also need a 66 blade. Terminating jacks is fairly easy and straightforward. One thing to remember is that when the sheath of your cable is cut back, make sure that there is no more than half an inch of wire exposed, and maintain the twists in your cable right up to the point of termination on the jack.

Patch panels

Patch panels come in different sizes, anywhere from 12 to 96 ports. We do not recommend using a 96-port patch panel, as it makes wire management a little more difficult. In our experience, the best size seems to be the 48-port. It allows a wire manager to be placed between each patch panel so that you have one row of cables going to the upper cable manager and one to the lower manager with no cables overlapping each other.

Tips

As you bring the cables out of the ceiling, tie them together in uniform bundles, but remember not to overtighten your tie wraps. Also make sure to pull your service loop into the ceiling somewhere above the data rack and secure it, so that should your data rack ever need to be moved, you have the additional length on the cables. When dropping the cables from the ceiling, it may be easiest to take them out of the ceiling straight down to the data rack and your patch panels. If there are too many cables to hang them from the ceiling without putting stress on them, or if they need to route to more than one data rack, you may need to purchase some sort of wire management from your electrical supply. Install it so that your cables can rest on the cable management and transition smoothly down to your patch panels.

Once you have brought your cables to the patch panels, terminate them using the same principles applied to terminating your jacks. Do not take off more than one half inch of sheathing from the end of the cable, and maintain your twists all the way to the termination point on the patch panel.

If you don’t already have a basic understanding of cable termination, you will likely need some hands on and visual references to be able to complete this process.