Networking

Within the walls: The art of the cable run

The art of running network cable is often underappreciated. Jack Wallen, Jr. has laid many a mile of cable and developed a keen sense for the job. Take a load off as he shares some tips and tricks on conduit, free-run cables, and more.

Running network cable is an art that should garner your full attention when the time comes. For a long time, I worked as a professional audio installation technician with an amazing little mom-and-pop company (IRC Audio). My duties included hanging speakers from various dangerously high locations, varnishing, staining, and painting outrageously expensive loudspeakers ("Jack, that speaker you're painting is about three months pay. I'd be careful!" my boss would fondly say), and running cables of all sorts.

To say that we ran miles and miles of cable in the strangest and snuggest of places would be an understatement. To say that we had to come up with creative means to get a run of cable from point A to point B would really be an understatement. I’m going to share the tips and tricks I learned while doing it.

Universality
You may ask yourself, "What does that have to do with running networking cable?" Well, my friend, some universal truths do exist. Although some specifics don't apply, many of the fundamentals are the same.

Terminology
You’ll need to know some terms throughout this Daily Drill Down:
  • AWG stands for American Wire Gauge, which rates the size of a wire. The size of this number is inversely proportional to the size of the wire (smaller number = larger diameter wire).
  • Bonding is the process of connecting two or more conductive objects by means of a conductor so that there is no conductive gap between the objects.
  • Grounding is the process of connecting one or more conductive objects to the earth so that the earth can act as an electromagnetic "sink."
  • Shielding prevents electrical noise from creating false digital signals and from corrupting analog signals.
  • Plenum: Actually, the term plenum refers to the air-return area in an HVAC system. The term has also been commonly adopted in many fields to mean a fire-retardant cable (or heat-retardant) cable.
  • EMI stands for electro-magnetic interference.
  • HVAC is the acronym for Heating, Ventilating, and Air Conditioning systems.

Conduit vs. free run
ANSI
Understand that it’s always best to adhere to American National Standards Institute (ANSI) specifications. Regardless of whether you’re running cable in your home or in a larger organization, following standards will ensure not only your safety, but also your liability.

Conduit is a means to safely route wire from one location to another. It’s used when the wire either needs protection from various elements (heat, electrical interference, traffic, etc.) or when it’s aesthetically pleasing. Conduit comes in two types: conducting (metallic) and nonconducting (plastic or some variation). Typically, you’ll see the following types of conduit used:
  • Electrical Metallic Tubing (EMT): This type is very versatile, due to its availability, cost, and ease of use.
  • Rigid Metal Conduit (RMC): This type is very solid and offers much better bonding and grounding.
  • Rigid Nonmetallic Conduit (RNC): This type is very simple to work with. It can be applied with standard tools but doesn't offer the shielding and grounding that conducting conduit offers.

A few other types of conduit are available, but this list will typically get you where you need to go.

Although it may be tempting to gravitate to RNC-type conduit, remember this: It’s simple to use, but you’ll have to run extra wire within the conduit to act as ground and bonding wires. You should also consider that RNC doesn’t offer shielding, so location of this type of conduit will be critical. You won’t want to use RNC around anything that could cause corruption to transmitted data, such as fluorescent lighting, power wiring, and sound equipment. Fortunately, Cat-5 Ethernet cabling offers fairly good EMI immunity. Regardless of its immunity, it's always best to be safe than sorry.

How do you decide whether to run free lines or use conduit? The answer can be a bit conditional. The guideline you should follow is this: If you’re using nonplenum cable for your run, you should be running in conduit. Why? Safety. The inclination for most is going to be to get the job done as quickly as possible; however, this can lead to severe problems, such as fire, if caution is not used.

Err on the side of caution. If you know for sure that you’re not running line anywhere near a hot location (such as lighting, HVAC, etc.), a damp location, a location rife with EMI, or a location where aesthetics is not crucial, then it’s safe to run your line without conduit. If you do run the risk of any of the above conditions, be smart and take the time to install conduit. Not only will your network runs be safer, they’ll also last much longer, thanks to the protection offered by conduit.

Installing conduit
The art of installing conduit is one that takes a long time to master. Of course, most of you won’t be concerned with taking it to an art form. In that case, here are some guidelines you’ll want to follow:
  • Make sure you have your run mapped out correctly and your measurements are on target. It’s always best to plan this out with a to-scale blueprint of the building you’re working within. Plan your run so that the conduit will be easily accessible.
  • Plan the number of bends in the conduit carefully. The fewer bends, the easier the wire pull will be.
  • Try to keep your conduit parallel to walls and ceilings to keep it more easily located.
  • Choose conduit diameter with expansion in mind. It's better to have wasted space than to have to run more conduit along the same run.
  • If you need them, precut holes for conduit in headers and joists before you begin your run.
  • Before cutting your conduit, make sure you have measured with couplings, fittings, and junction boxes in mind.
  • Cut EMT tubing with a hacksaw or bandsaw; don’t use roll-type tube cutters.
  • Always dry-fit your conduit before applying adhesives.
  • Don’t attempt to bond painted surfaces, as the paint can easily detract from the conductibility of the material.

Conduit doesn’t have to be difficult to install. Your primary objective when beginning this installation is giving yourself enough time to carefully plan and execute the installation.

Free-run cables
Running cables without conduit is a much faster method of routing networking cables. The biggest problem you’ll run across with this method is sloppiness. With the help of conduit, you’ll finish with a neat, secure, and safe installation. Without conduit in place, your run can lean towards sloppy and haphazard, which should, of course, be avoided.

Avoiding slop is possible, primarily, through careful planning. As with a conduit installation, you’ll want to have a blueprint of the structure you’ll be installing within.

When I'm doing free-run cables, I tend to stick to routing my cable along seams and ceiling-tile tracks (so long as these seams don’t run along anything that would cause interference). Here are some tips that should aid you in running free cable:
  • Plan ahead and buy in bulk. You'll save both time and money.
  • Use the best cables you can afford. Don't try to skimp in this area because these beauties will need to be around for a long time.
  • Make sure you measure your runs, keeping in mind the distance limitations of the type of wiring you’re using. If you need to use repeaters or concentrators, make sure you strategically locate them for best access and use.
  • Always run more cables than you think you need so you’ll have room to expand, and terminate cables only when needed.
  • The minimum bend radius for Unshielded Twisted Pair is four times the cable’s outside diameter (approximately one inch). For multipair cables, the minimum bending radius is 10 times the outside diameter.
  • Don’t use multibundled cables. They’re much more difficult to run for numerous reasons (weight, increased bend radius).
  • Mark your cables before you make your run, and standardize your color-coding scheme.
  • Wait until the run is complete before you tie anything down.

Creative cable-running tips
Everyone has his or her own methods. Some are fairly pedestrian, and some are amazingly clever. A technician I worked with was a rather industrious fellow who took advantage of his surroundings. On two particularly tricky occasions, this man's strange perspective came in quite handy. The first was a long, straight run within a very large conduit. The conduit was empty, and it seemed as if we weren’t going to get the pull line from one end of the conduit to the other. After thinking awhile, this guy found a remote control car, tied the pull line to the antenna, put the car in the conduit, and drove the car to the other end.

The second incident might seem a bit cruel, but it really wasn’t. The installation was a PA system for a horse stable. The run was to go across the entire length of the barn, but the ceiling it was to run on was not strong enough to support a human. Being the resourceful man he was, he located the nearest barn cat, tied the pull line to the cat's collar, put the cat on the ceiling, and called the cat to the other side. None of us knew why the cat actually came to him, but it did, and the run was successful.

These two stories only illustrate that there are limitless ways to get your pull line to its destination. If you're looking for a more standard approach, you’ll want to look at a plumbing snake. These coiled spring-like wires, which can be rented at most tool rental shops, are perfect for fishing through conduit to run a pull line. Once you have fished the snake through the conduit (the snake must be longer than the conduit run, of course), attach the pull line to the end of the snake and pull the snake back out. Be careful to securely attach your pull line to the snake or else you'll be pushing the snake back through the conduit.

With the pull line through, you can now attach the Cat-5 (or whatever type of line you're pulling) to the pull line. One very simple way to make this attachment is to fold one of the Cat-5 cables into a loop and use electrician’s tape to hold the loop together. You now have a perfect place to tie the pull line.

Before you actually begin pulling your cable through, do yourself a favor and lubricate the cable. Although you may assume your run is a straight shot from point A to point B, you can’t be sure how much friction will build up and whether the cable will get caught up. A number of different cable pulling lubrications are available. Here’s a small listing of some of the better lubes:

Conclusion
Running cable shouldn't be rushed or done without forethought. In fact, with careful planning and design, a good cable-run job will outlast most of your networking equipment and probably many of your employees.

Take the time to design your cable runs as you would your networking infrastructure. The money you'll save in the long run (in the form of man hours, primarily) will be a welcome relief in tough times. Although not the work of Michelangelo, the art of cable running should be taken seriously and patiently.

About

Jack Wallen is an award-winning writer for TechRepublic and Linux.com. He’s an avid promoter of open source and the voice of The Android Expert. For more news about Jack Wallen, visit his website getjackd.net.

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